Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmin Mohamed Fayez;Mohamed Abdelkawy;Hoda M. Marzouk

03/11/2023

https://www.sciencedirect.com/science/article/abs/pii/S0026265X23012006

Hayam Mahmoud Lotfy Ibrahim Mahmoud

arah S. Saleh, Heba T. Elbalkiny

25/10/2023

https://www.rsc.org/journals-books-databases/about-journals/environmental-science-processes-impacts/

Hayam Mahmoud Lotfy Ibrahim Mahmoud

20/10/2023

https://www.sciencedirect.com/science/article/abs/pii/S2352554123003224

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmin Mohamed Fayez; M. Abdelkawy; Shereen A. Boltia; Reem H. Obaydo

01/09/2023

https://www.sciencedirect.com/science/article/abs/pii/S2352554123002590

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Hoda M. Marzouk; Reem H. Obaydo; Yasmin M. Fayez;Mohamed Abdelkawy

19/08/2023

https://bmcchem.biomedcentral.com/articles/10.1186/s13065-023-01015-z

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Kanaka Parvathi Kannaiah, Hemanth Kumar Chanduluru, ,Reem H.Obaydo, Nevin Erk, , Manikandan Krishnan, Mohamed A.El Hamd

03/08/2023

https://www.sciencedirect.com/science/article/abs/pii/S2352554123002310?via%3Dihub

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Shereen A. Boltia; Yasmin M. Fayez; M. Abdelkawy

18/05/2023

https://www.sciencedirect.com/science/article/pii/S2405844023034916

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Reem H. Obaydo , Ekram H. Mohamed

26/04/2023

https://www.sciencedirect.com/science/article/pii/S2666831923000474?via%3Dihub

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Amr M. Mahmoud; Yasmin M. Fayez; Mohamed Abdelkawy; Hoda M. Marzouk

24/03/2023

https://iopscience.iop.org/article/10.1149/1945-7111/acc361/meta

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Adel M. Michael, Christine K. Nessim

23/03/2023

https://www.sciencedirect.com/science/article/abs/pii/S0026265X23002874?via%3Dihub

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Reem H. Obaydo, Christine K. Nessim

13/01/2023

https://www.sciencedirect.com/science/article/abs/pii/S2352554123000141?via%3Dihub

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmin M.Fayez;Hoda M.Marzouk

15/08/2022

https://www.sciencedirect.com/science/article/pii/S2352554122002108?via%3Dihub

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmin M.Fayez ; Hoda M.Marzouk

09/08/2022

https://www.scielo.br/j/bjps/a/58CptgpmGvwCTkfn4KYzwnc/?lang=en

Hayam Mahmoud Lotfy Ibrahim Mahmoud

29/07/2022

https://pubmed.ncbi.nlm.nih.gov/35901458/

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Hoda M. Marzouk ; Yasmin M. Fayez

18/06/2022

https://www.sciencedirect.com/science/article/pii/S1386142522006722

Hayam Mahmoud Lotfy Ibrahim Mahmoud

03/06/2022

https://www.sciencedirect.com/science/article/abs/pii/S0045653522015673?via%3Dihub

Hayam Mahmoud Lotfy Ibrahim Mahmoud

20/04/2022

https://www.sciencedirect.com/science/article/pii/S138614252200405X

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmin Mohammed Fayez,

22/12/2021

https://academic.oup.com/jaoac/article-abstract/105/3/717/6478289

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Dina Abbas Ahmed

01/05/2021

A comparative study of successive spectrophotometric resolution technique for the simultaneous determination of a challengeable quaternary mixture of Chlorpheniramine maleate (CPM), Pseudoephedrine hydrochloride (PSE), Ibuprofen (IBU) and Caffeine (CAF) is presented, without preliminary physical separation steps. Several successive steps were applied on built-in spectrophotometer software utilizing zero and/or derivative and/or ratio spectra of the studied components. These methods, namely, Dual amplitude difference (DAD) as a novel method, Constant multiplication coupled with spectrum subtraction method (CM-SS), Factorized first derivative coupled with derivative transformation method (FD¹ -DT) and Derivative ratio method (DD¹).The calibration graphs are linear over the concentration range of 10.0–80.0 μg/mL,150.0–900.0 μg/mL, 200.0–1400.0 μg/mL and 3.0–30.0 μg/mL for CPM, PSE, IBU and CAF, respectively. The specificity of suggested methods was studied via laboratory prepared (diverse ratios) mixtures and were successfully applied for Antiflu® capsules' analysis. Moreover, sample enrichment via In Silico (via software of spectrophotometer) and In Lab (via spiking with pure sample) techniques was elected for a pharmaceutical dosage form analysis comprising CPM and PSE as minor components. Accuracy, precision and specificity were between the valid limits. Validation steps were done in accordance with the ICH guidelines. Moreover, statistical comparison was carried out between the obtained and reported results for pure powder form and no significant difference appeared.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Reem H. Obaydo, Duaa J. Al Zakri1, Amir Alhaj Sakur

01/02/2021

Background The pharmaceutical industry and the National Regulatory Authorities are now focusing on the quantification of multi-component drugs for quality control testing. Main body Recently, the utilization of the ultraviolet spectrophotometric methods has become vital for the analytical studies for the routine analysis of different fixed-dose combination products either in the presence of a minor component in their combination or not. This article reviewed several published methods to those that have been applied to quantify some pharmaceutical combinations containing minor components through the last two decades. Conclusion The applied spectrophotometric methods are labor, time-saving, and also considered a cheap substitute for the overpriced high-performance liquid chromatographic technique.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

MeltemÖztürk, GizemTiris, NevinErk, Sarah S.Saleh,

01/02/2021

Versatile, extraction-free univariate spectrophotometric methods have been modified to get effective spectral resolution of mixtures in accordance with their feature challenges. The proposed methods have been applied and validated for analyzing some antihypertensive medicines in their co-formulated medicinal products. Two mixtures have been used: the first one [Mix I (OLM/ADB)] is composed of Olmesartan medoxomil (OLM) and Amlodipine besylate (ADB) with partly-overlapped spectra while the second [Mix II (TEL/HCT)] is made up Telmisartan (TEL) and Hydrochlorothiazide (HCT) with total-overlapped spectra. Induced dual wavelength, absorbance correction and ratio subtraction coupled with constant multiplication methods were applied to Mix I (OLM/ADB), while dual wavelength, advanced absorbance subtraction and constant center coupled with spectrum subtraction methods were applied to Mix II (TEL/HCT). Calibration graphs were established with good correlation coefficients. The methods exhibit significant advantages as simplicity, sensitivity, minimal data manipulation besides optimum robustness. Selectivity was inspected using lab-mixtures with diverse ratios. Accuracy, precision and repeatability were found to be within the acceptable limits. The proposed methods are good enough to be used for co-assay of analytes in combined forms without any interfering from excipients. Moreover, all results were estimated in accordance with ICH criteria and successfully compared with those of the reported methods applying t-test and F-test at 95% confidence level. Generally, these methods can be used efficiently for routine quality control testing.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Reem Hasan Obaydo , Amir Alhaj Sakur.

01/01/2021

Objectives: The pharmaceutical industry and the National Regulatory Authorities (NRAs) are now focusing on the dissolution of multi-component drugs for quality control testing and predicting in vivo results to further consolidation of the biowaiver concept. The mixed formulation of Ciprofloxacin hydrochloride (CIP) and Metronidazole (MET) have been used as a model for simultaneous determination and obtaining in vitro dissolution profiles by using green analysis method namely (UV-CWT(Db4, a=490)). Material and methods: The proposed method (UV-CWT(Db4, a=490)) includes UV detection combined with Continuous Wavelet Transform (CWT) with Daubechies family and the order of fourth at the scaling factor (a=490) has been used and validated for analyzing and obtaining the dissolution profiles of the fixed-dose combination (CIP-MET). Results: The proposed method (UV-CWT(Db4, a=490)) has been validated effectively in accordance with ICH rules, regarding linearity, specificity, rigor, and preciseness of the working range (3.0–16.0 μg/mL) for both (CIP) and (MET), respectively. As well as figures of merit were concluded. The dissolution profiles of CIP-MET tablets were acquired by the proposed (UV-CWT (Db4, a=490)) and HPLC reported methods were conveniently compared using the indicators f1 and f2 ("difference" and "similarity") the results ensured that there were no statistically differences between the methods. In addition, the green assessment tool, namely analytical eco-scale, evaluated and compared the greenness of the suggested method (UV-CWT(Db4, a=490)) and HPLC reported one. Conclusion: the suggested process (UV-CWT(Db4, a=490)) was considered as an excellent green, rapid, accurate, economical and minimum-steps method for simultaneously resolve and construct the dissolution curves of a fixed-dose combination drug (CIP-MET) in a short time and without the use of organic solvents, enabling significant labor and resource savings.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Hany Hunter Monir Bebawi Adel Michael,christine K. Nessim,Yasmin Fayez

01/12/2020

This study presents comprehensive comparative study of different eco-friendly spectrophotometric approaches without any sample treatment on processing quaternary mixture of sulphadimidine sodium (SDS), sulphaquinoxaline sodium (SQS), diaveridine (DVD) and vitamin K3 (VTK3). The different univariate complementary resolutions according to the response used for the assay of the cited drugs after applying the processing steps were implemented using successive ratio subtraction coupled with constant multiplication (SRS-CM), absorbance subtraction (AS) and amplitude modulation (AM). On the other hand, multivariate spectrophotometric models were developed and validated for simultaneous determination of the cited mixture. Resolution was accomplished by using two multivariate calibration greener models, including principal component regression (PCR) and partial least-squares (PLS). The proposed approaches are considered environmentally friendly since they use only water as reagent, which is cheap and safe for the operator. The calibration graphs are linear over the range of (4.0–13.0) μg/mL for (SDS), (1.0–10.0) μg/mL for (SQS), (1.0–11.0) μg/mL for (DVD) and (1.0–8.0) μg/mL for (VTK3). Specificity of the applied procedures was assessed by analyzing the laboratory-prepared mixtures and their combined dosage form. The outcomes of the developed methods were statistically compared with those of the official and reported methods; using Student's t-test and F-test, showing no significant difference. The proposed methodologies can be used for the routine analysis of the cited drugs in quality control laboratories.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Sarah S ,Gizem Tiris , Yasmin Rostom

01/12/2020

The green profile of the proposed method was assessed and compared with reported classical methods via four tools of greenness which are: Eco-Scale, National Environmental Methods Index (NEMI), Assessment of Green Profile (AGP) and Green Analytical Procedure Index (GAPI). A simple, precise and rapid (RP-HPLC) has been developed for the quantification of Indapamide (IND), perindopril (PER) arginine and amlodipine besylate (ADB) in binary and ternary mixtures. A greener alternate RP-HPLC method was presented for the determination of pharmaceutical combinations composed of the cited medications using an eco-friendly eluent and quick run time with the least waste yield. Chromatographic separation was achieved using Waters Spherisorb ODS-2 C18 column (150 × 4.6 mm, i.d., 5 μm) and eluent formed of acetonitrile : phosphate buffer (20 mM, pH = 3): methanol in the ratio of (65: 30: 5, by volume) at flow rate 1.0 mL/min with DAD-detection at 220 nm. This procedure was valid over linearity ranges of 0.5–20 μg/mL, 2.5–40 μg/mL and 2–40 μg/mL for IND, PER and AML, respectively. The presented chromatographic method was completely validated regarding ICH guidelines and were statistically compared with those of the reported methods applying t-test and F-test at 95% confidence. The proposed method was found to be greener in terms of usage of hazardous chemicals and solvents, energy consumption, and waste production.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Ekram H.Mohamed

01/10/2020

An innovative strategy was developed for the estimation of a fixed dose combination containing Alogliptin (ALO) and pioglitazone (PIO) using induced concept for resolving the overlapped spectra, lacking isoabsorptive point. This strategy is based on coupling factors as numerical values or ratios as spectrum form with the recorded signals leading to induced mathematical filtration of the drug of interest and complete elimination of the interfering one in the combination without prior physical separation. The calculated factors were factor of equality in induced dual wavelength (IDW) or absorptivity factor in induced concentration subtraction method (ICS) while absorptivity ratio spectrum for induced amplitude modulation method (IAM). The calibration curves displayed linearity within 1.0-16.0 μg/mL for ALO and 2.0-22.0 μg/mL for PIO with good correlation coefficients. The induced methods specificity was also assured through the assaying different synthetic mixtures prepared to contain the two drugs in ratios approaching the ratio actually found in the marketed dosage form. The methods were applicable and suitable for estimating ALO and PIO in both bulk form and their fixed dose combination. Induced methods have been extensively validated in accordance with ICH guidelines and results demonstrated the accuracy and reproducibility in comparison to the reported method.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Hany Hunter Monir Bebawi, Adel Michael,christine K. Nessim,Yasmin Fayez

01/09/2020

Background The impact of mathematical manipulation on the efficiency of smart spectrophotometric approaches was considered for analyzing a veterinary binary mixture of tylosin tartrate (TYT) and doxycycline hydrochloride (DOX) .Objective Based on subtraction which can be response subtraction via numerical factor calculation between two wavelengths. Method Absorbance subtraction (AS) and amplitude summation (A-Sum), or subtraction of constant value or spectrum, was used to eliminate the contribution of the interfering component, as is done in spectrum subtraction (SS), extended ratio subtraction (EXRS), ratio subtraction (RS), and derivative subtraction (DS), or multiplication of a constant value by the divisor to get the spectrum of one component, or division by the normalized spectrum to modulate the original absorption spectrum to concentration as in concentration value and also detected in amplitude modulation (AM). The derivative transformation method (DT) is a form of mathematical manipulation that transforms a derivative to its original absorption form.Results The consumption of these methods will become more significant in quality control departments for the repetitive quantitative analysis of different veterinary products in both research and industry laboratories. Some manipulations may be used for simultaneous analysis of DOX and TYT, such as absorbance subtraction, amplitude modulation, ratio subtraction and derivative subtraction coupled with spectrum subtraction, concentration value, and amplitude summation, while others may be used for DOX only, such as derivative transformation and constant value Conclusions The recovery percentages confirmed that the accuracy and the reproducibility were approved by the following ICH guidelines.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Dina Abbas Ahmed, Mohamed Khaled Abdel Rahman and Soheir Abdel Fattah Weshahy

01/08/2020

Accurate, rapid and selective reversed phase ultra-performance liquid chromatography method with UV detection has been established and validated for the synchronous determination of aceclofenac (ACE) and diacerin (DIA) in the occurrence of diclofenac sodium and rhein, their main degradation products, respectively. Chromatographic separation was accomplished using Inertsil C-18 column (50 × 2.1 mm i.d., 1.7 μm particle size) in isocratic mode, with mobile phase consisting of 20 mM ammonium acetate buffer:acetonitrile in the ratio of 42:58 (v/v), pH adjusted to 3.00 by using 10% acetic acid, the flow rate of 0.25 mL/min and UV detection was performed at 265 nm. The retention times were 2.00 +/− 0.24, 2.69 +/− 0.19, 4.00 +/− 0.23 and 5.24 +/− 0.25 min for DIA, rhein, ACE and diclofenac sodium, respectively. Excellent linearity was shown over a range of 1.0–150.0 μg/mL and 0.5–87.5 μg/mL with mean percentage recoveries of 98.87 ± 1.19 and 98.84 ± 1.08 for ACE and DIA, respectively. Parameters of precision and accuracy of the method meet the established criteria. The obtained RSD values were quite low and indicate good reproducibility of the method. Thus, the developed method can be used for the combined dosage form analysis and its chemical stability studies.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Ahmed DA, El-Rahman MKA, Lotfy HM, Weshahy SA

01/07/2020

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Mohamed K Abd El-Rahman, Soheir A Weshahy

01/06/2020

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Fayez YM, Michael AM, Monir HH, Nessim CK.

01/05/2020

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Elshahed MS, Mohamed D.

01/05/2020

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Lotfy HM, Fayez YM, Michael AM, Nessim CK.

01/03/2020

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Fahmy NM.

01/03/2020

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Monir HH, Erk N, Rostom Y.

01/01/2020

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Morgan EM, Fayez YM

01/12/2019

Hayam Mahmoud Lotfy Ibrahim Mahmoud

El-Hanboushy S, Fayez YM

01/12/2019

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Shendy AH, Eltanany BM, Al-Ghobashy MA, Gadalla SA, Mamdouh W

01/12/2019

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Dina A. Ahmed, Mohamed K. Abd El-Rahman, Soheir A. Weshahy

01/12/2019

Oral pharmaceutical preparation containing pseudoephedrine hydrochloride (PSE) and ibuprofen (IBU) is widely prescribed as over- the- counter (OTC) for treatment of common cold-sinus. Development of four precise and accurate spectrophotometric methods are established for the concurrent determination of (PSE) and (IBU)in this preparation exploiting zero and/or ratio spectra. Method I is a dual wavelength method (DW). method II is a ratio difference method (RD), method III is a constant multiplication coupled with spectrum subtraction method (CM-SS) and method IV is a constant center coupled with spectrum subtraction method (CC-SS). While, absorbance correction method (AC) is successfully established for the determination of (IBU) only exploiting zero order absorption spectra. The calibration curves are linear over the concentration range of 100.0–900.0 μg/mL for (PSE) and 200.0–1000.0 μg/mL for (IBU). No separation steps are required for the spectrophotometric procedures which augments their simplicity. Analyzing synthetic mixtures of the cited drugs evaluated the specificity of the applied methods. Validation of the analysis results have been statistically performed confirming the accuracy and reproducibility of the proposed method through recovery studies which were carried out by following ICH guidelines. Thus, the developed methods can be successfully applied routinely in quality control laboratory.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Dalia Mohamed,Mona S. Elshahed

01/11/2019

Dapagliflozin (DPF) and saxagliptin (SXG) are currently co-formulated in a tablet dosage form which is prescribed to improve glycemic control. The absorption spectra of DPF and SXG were highly overlapped which completely hindered their simultaneous estimation at their λmax 224 nm and 209 nm, respectively. Thus, in this work three smart and simple univariate spectrophotometric methods were originally established and validated for the first time in order to quantitatively estimate DPF and SXG in bulk forms and in combined pharmaceutical formulation without the requirement for any initial separation or treatment. These methods are; factorized zero order method (FZM), factorized derivative method (FDM) and factorized ratio difference method (FRM). These methods were capable of determining DPF and SXG over the range of 2.5–50.0 μg/mL and 2.5–60.0 μg/mL, respectively. All the developed methods are based on a novel and unique approach for the spectral recovery of unresolved spectra named; factorized response spectrum (FRS). The exclusivity of the FRS originates from its ability to completely resolve the cited drugs in the mixture and retrieve their original spectra. Selectivity of all proposed methods was assessed by comparing the obtained results of the mixture analysis with those of the pure powdered drugs. Validation of the newly developed methods was applied as recommended by the ICH demonstrating acceptable accuracy and precision. In general, these methods could be effectively employed for the routine quality control investigation of bulk materials and available market formulations.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmin M. Fayez

01/09/2019

Background Simple, specific, accurate, and precise spectrophotometric methods are progressed and validated for concurrent analysis of pseudoephedrine sulphate (PSE) and loratadine (LOR) in their combined dosage form depending on spectral analysis procedures. In this binary mixture, pseudoephedrine (PSE) could be determined by using its resolved spectrum of zero-order absorption at 256.8 nm after subtraction of the spectrum of LOR, and also it could be determined in existence of the spectrum of LOR by different methods including absorption correction method (AC) at 256.8 nm and 280 nm, dual wavelength method (DW) at 254 nm and 273 nm, induced dual-wavelength method (IDW) at 230 nm and 263 nm, and ratio difference method (RD) at 256.8 nm and 270 nm. Loratadine (LOR) in the binary mixture could be determined either by direct analysis at 280 nm without any contribution from the spectrum of PSE or through its recovered spectrum of zero-order absorption via constant multiplication method (CM) using plateau region (277–326 nm). Also, concurrent determination for PSE and LOR in their overlapped binary mixture could be achieved by applying induced amplitude modulation (IAM) method. Results Specificity of the proposed spectrophotometric methods was examined by the analysis of prepared mixtures in laboratory and was applied successfully for pharmaceutical dosage form analysis which has the cited drugs without additive contribution. The proposed spectrophotometric methods were also validated as per the guidelines of ICH. Statistical comparison was performed between the obtained results with those from the official methods of the cited drugs, using one-way ANOVA, F test, and Student’s t test, and the results exhibit insignificant difference concerning precision and accuracy. Conclusions The previously proposed spectrophotometric methods could be easily used accurately and precisely for simultaneous determination of the studied binary mixture with simple manipulation procedures.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Nevin Erk, Yasmin Rostom

01/07/2019

Spectral numerical factor techniques have been developed for quantification of a new pharmaceutical combination. Five simple, fast and accurate spectrophotometric methods using spectral factor manipulation have been tested and validated so as to determine quantitatively a new fixed-dose combination tablet containing both amlodipine besylate (ADB) and rosuvastatin calcium (ROS). Namely, these methods are induced dual wavelength, absorbance correction, absorbance subtraction, amplitude correction and advanced amplitude subtraction. Their corresponding spectral factors are equality, absorption, absorbance, amplitude and unity factor, respectively. Calibration curves of ADB and ROS were set up for all the previously mentioned methods under the optimum conditions in a concentration range of 3.0–21.0 μg/mL with correlation coefficients ≥0.9990. Selectivity was calculated by analyzing laboratory-prepared synthetic blends of the cited drugs. A comparative study between these methods and the reported ones has been carried out statistically forming a judgment that the difference between both results is totally insignificant. Actually, the suggested spectral factor technique is so effective for use in routine laboratory essay owing to its simplicity, rapidity and precision. Generally, the proposed factor procedures have the ability to run smoothly without any interference from additives that may deteriorate analysis efficiency of a pharmaceutical combination

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmin Mohammed Fayez, Mohamed K. Abd El-Rahman

01/07/2019

The possibility of obtaining continuous analytical signal excluding any pre-treatment of sample is the most environmental friendly method of analysis. In the current manuscript, a solid contact sensor was fabricated for dual purpose; firstly, determination of valaciclovir hydrochloride (VAL) in existence of its acid induced degradation product, Guanine (GUA) and secondly, real time acquisition of the dissolution profile from its pharmaceutical formulations (Valtrex) and (Valysernex). The sensing membrane was fabricated using a polyvinyl chloride (PVC), sodium tetraphenyl borate as a cation exchanger with bis (2-ethylhexyl) sebacate as a plasticizer. The proposed sensor displayed fast, stable Nernstian responses across VAL concentration range (1 × 10−5 M to 1 × 10−2 M). The opportunities of the proposed sensor with respect to other off-line classical techniques originates from being in-line, time saving, cost-effective, green and simple. ICH guidelines were followed to ensure validation of the proposed method concerning accuracy and precision.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Mohamed Khaled Abdel Rahman, Soheir Abdel Fattah Weshahy,

01/05/2019

Six simple, sensitive and selective spectrophotometric methods based on mathematical filtration technique are presented for concurrent determination of aceclofenac (ACE) and paracetamol (PAR) in presence of their degradation products, namely; diclofenac sodium (DIC) and 4-aminophenol (4-AP), respectively without preliminary physical separation procedures. This technique consists of several consecutive steps applied on built-in spectrophotometer software utilizing zero and/or derivative and/or ratio spectra of the studied components. These methods, namely, dual wavelength (DW), induced dual wavelength (IDW), derivative subtraction (DS) coupled with constant multiplication (CM), ratio difference method (RD), constant center method (CC) and the novel introduced unlimited derivative ratio method (UDD). This novel method has a very powerful competence for the analysis of the challengeable mixtures lacking zero crossing point. The linearity, accuracy and precision ranges of these methods were determined and validated as per ICH guidelines. Moreover, the specificity was checked by analyzing synthetic mixtures of both drugs. These methods were applied for the determination of the cited drugs in pharmaceutical formulation and a statistical comparison of the obtained results was made with each other and with those of reported spectrophotometric method. The comparison of the results of pure powder form showed that there is no significant difference between the proposed methods and the reported method regarding both accuracy and precision.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmine M. Fayez

01/05/2019

An electro-analytical procedure was progressed for quantitative determination and monitoring the dissolution behavior of both cationic pseudoephedrine sulfate (PSE sulfate) and loratadine (LOR) drugs in their binary mixture with each other and ternary mixture with paracetamol (PAR) by in-line potentiometric analysis system without a need for pre-treatment or derivatization of the sample. This approach is performed by measuring continuously the increase in the generated emf over time by incorporating an in-site selective electrode for PSE sulfate and LOR fabricated utilizing polymeric membrane of poly (vinyl chloride) (PVC), tetraphenyl borate (TPB) and potassium tetrakis (4-chlorohenyl) borate (KTCPB) as a cation exchanger, Bis(2-ethylhexyl) sebacate and nitrophenyl octyl ether (NPOE), were utilized as plasticizers for determination of PSE sulfate and LOR, conjointly. The proposed sensors for both drugs exhibited stable and fast responses over wide PSE sulfate and LOR concentration range (2 × 10−5 to 2 × 10−2 mol/L regarding PSE sulfate while 1 × 10−5 to 1 × 10−2 mol/L regarding LOR). Afterwards, the proposed potentiometric method's validation was performed, and it is supposed to be eco-friendly and green technique in which consumption of solvents and sample pre-treatment were not mandatory for its application.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Shereen Mostafa Tawakkol, Yasmin Mohammed Fayez, Nesma Mahmoud Fahmy, Mostafa Abdel-Atty Shehata

01/03/2019

Two stability-indicating chromatographic methods for the determination of clotrimazole and its two acid induced degradation products, with dexamethasone acetate without prior separation. First method depends on RP-HPLC utilizing ODS-3 Inertsil C18 column. Mobile phase consists of acetonitrile:phosphate buffer (pH 6.0) in ratio (65:35, v/v) with flow rate 1.5 mL/min and UV-detection at 220 nm. Linearity range 1.0–75.0 μg/mL for clotrimazole and 2.0–75.0 μg/mL for dexamethasone with mean percentage recovery of 99.49 ± 1.10 for CLT and 99.60 ± 1.06 for DA. Second method depends on HP-TLC. Developing system is composed of chloroform:ethyl acetate in the ratio of (5:3.5, v/v), scanned at 220 nm. Linearity range 1.0–12.0 μg/band for clotrimazole and 1.0–20.0 μg/band for dexamethasone with mean R% of 99.33 ± 0.76 for clotrimazole and 99.77 ± 0.99 for dexamethasone. Conditions and parameters affecting the separation of the cited components without interference of the degradation products are tested and optimized. Suitability of the methods for quantization of the drugs concentrations is proven by validation as instructed from the ICH. Validation results and statistical treatment of the data demonstrate reliability of these methods. Kinetics of acid degradation process of clotrimazole are investigated by the proposed HPLC method and the order rate constant, half life and shelf life are computed.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Sarah S. Saleh

01/02/2019

everal spectrophotometric approaches utilize different functions of the iso-absorptivity coefficient in zero-order absorption signals and its manipulated spectra. This work introduced an investigation concerning the efficiency power of recent methods based on iso-absorptivity coefficient in different spectral signals. These methods were as follows: absorptivity centering method (a-Centering), absorbance subtraction method (AS), amplitude modulation method (AM,) and amplitude summation method (A-Sum). These methods were applied to determine the binary mixture of ofloxacin (OFX) and dexamethasone (DXM). Linearity of the proposed methods was investigated in the range of 1.0–10.0 μg/ml for both drugs. The proposed methods were validated as per ICH guidelines and were successfully applied for the simultaneous determination of OFX and DXM in their pharmaceutical preparation without interference from additives. Statistical analysis of the results obtained by the proposed spectrophotometric methods compared with a reported method revealed no significant difference between the proposed and reported methods, confirming accuracy and precision at 95% confidence limit.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Sarah S. Saleh

01/12/2018

The application of spectrophotometric techniques has shown a tremendous development over the past few years, where it is possible to determine the concentrations of several components in complex matrix. A new feature will be introduced in this work where the application of spectrophotometric techniques will be enhanced to resolution and checking the purity of signals. The finger-print resolution “ratio subtraction method” (RSM) was coupled with the novel complementary method “unified constant subtraction” (UCS); in addition to the methods: extended ratio subtraction method (EXRSM), constant multiplication (CM) or “spectrum subtraction” (SS). These techniques were applied for the determination of the complex matrix of the binary mixture of chloramphenicol and dexamethasone. By applying official spectrophotometric methods, direct determination of the components was allowed with no need for validation procedures. The spectrophotometric techniques were successfully applied to the laboratory prepared mixtures and the combined dosage form where the purity of the extracted signals were tested by calculating the spectral contrast angle (θ) and the spectral ratio factor (SRF) where the results were compared to show the capability to recover pure spectral profiles and detect the presence of impurities. The proposed methods proved that spectrophotometric techniques can be used for identification and separation of signals, similar to chromatographic techniques

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Soheir A. Weshahy , Mohamed K. Abd El-Rahman ,

01/11/2018

Attainment of the dissolution silhouettes of active ingredients in a pharmaceutical formulation containing multiple components is governed by off-line multistep chromatographic and spectroscopic methods. In this work, “Double-Dip” green analytical chemistry (GAC) approach with the eventual aim of progressing in-line potentiometric sensors for simultaneous attainment of the dissolution curves of dual active ingredients in a binary pharmaceutical dosage form is adopted. For the proof of concept, two selective and sensitive sensors were elaborated for the simultaneous detection of the cationic Pseudoephedrine (PSE) and the anionic Ibuprofen (IBU) drugs as well as monitoring their dissolution silhouettes. For detecting the cationic drug (PSE), PSE sensor was elaborated by the usage of potassium tetrakis (4-chlorophenyl)borate (KTCPB) being a cationic exchanger, while IBU sensor was established for detecting the anionic IBU using tridodecylmethyl ammonium chloride (TDC) being an anionic exchanger and 2-nitrophenyl-octyl-ether (2-NPOE) as a plasticizer for both sensors. Developing these novel sensors permits PSE and IBU's detection in bulk powder, in laboratory combinations and in complex dosage form and also their simultaneous in-line monitoring of their dissolution profiles. The benefits of the newly introduced “Double-Dip” approach are emphasized with a notably curtailing in solvent consumption and waste generation

Hayam Mahmoud Lotfy Ibrahim Mahmoud

01/09/2018

Several spectrophotometric techniques were recently conducted for the determination of binary mixtures of clotrimazole (CLT) and dexamethasone acetate (DA) without any separation procedure. The methods were based on generation of ratio spectra of mixture then applying simple mathematic manipulation. The zero order absorption spectra of both drugs could be obtained by the constant center (CC) method. The concentration of both CLT and DA could be obtained by constant value via amplitude difference (CV-AD) method depending on ratio spectra, Ratio difference (RD) method where the difference between the amplitudes at two wavelengths (ΔP) on the ratio spectra could eliminate the contribution of the interfering substance and bring the concentration of the other, and the derivative ratio (DD1) method where the derivative of the ratio spectra was able to determine the drug of interest without any interference of the other one. While the concentration of DA could be measured after graphical manipulation as concentration using the novel advanced concentration value method (ACV). Calibration graphs were linear in the range of 75–550 μg/mL for CLT and 2–20 μg/mL for DA. The methods applied to the binary mixture under study were successfully applied for the simultaneous determination of the two drugs in synthetic mixtures and in their combined form Mycuten-D cream. The results obtained were compared statistically to each other and to the official methods.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmin Rostom Omran

01/07/2018

A novel, simple, rapid, accurate, and economical spectrophotometric method, namely absorptivity centering (a-Centering) has been developed and validated for the simultaneous determination of mixtures with partially and completely overlapping spectra in different matrices using either normalized or factorized spectrum using built-in spectrophotometer software without a need of special purchased program. Mixture I (Mix I) composed of Simvastatin (SM) and Ezetimibe (EZ) is the one with partial overlapping spectra formulated as tablets, while mixture II (Mix II) formed by Chloramphenicol (CPL) and Prednisolone acetate (PA) is that with complete overlapping spectra formulated as eye drops. These procedures do not require any separation steps. Resolution of spectrally overlapping binary mixtures has been achieved getting recovered zero-order (D0) spectrum of each drug, then absorbance was recorded at their maxima 238, 233.5, 273 and 242.5 nm for SM, EZ, CPL and PA, respectively. Calibration graphs were established with good correlation coefficients. The method shows significant advantages as simplicity, minimal data manipulation besides maximum reproducibility and robustness. Moreover, it was validated according to ICH guidelines. Selectivity was tested using laboratory-prepared mixtures. Accuracy, precision and repeatability were found to be within the acceptable limits. The proposed method is good enough to be applied to an assay of drugs in their combined formulations without any interference from excipients. The obtained results were statistically compared with those of the reported and official methods by applying t-test and F-test at 95% confidence level concluding that there is no significant difference with regard to accuracy and precision. Generally, this method could be used successfully for the routine quality control testing.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmin M.Fawzy, Christine K.Nessim

01/06/2018

Two simple and accurate chemometric-assisted spectrophotometric models were developed and validated for the simultaneous determination of chlordiazepoxide (CDZ) and clidinium bromide (CDB) in the presence of an alkali-induced degradation product of CDB in their pure and pharmaceutical formulation. Resolution was accomplished by using two multivariate calibration models, including principal component regression (PCR) and partial least-squares (PLS), applied to the UV spectra of the mixtures. Great improvement in the predictive abilities of these multivariate calibrations was observed. A calibration set was constructed and the best model used to predict the concentrations of the studied drugs. CDZ and CDB were analyzed with mean accuracies of 99.84 ± 1.41 and 99.81 ± 0.89% for CDZ and 99.56 ± 1.43 and 99.44 ± 1.41% for CDB using PLS and PCR models, respectively. The proposed models were validated and applied for the analysis of a commercial formulation and laboratory-prepared mixtures. The developed models were statistically compared with those of the official and reported methods with no significant differences observed. The models can be used for the routine analysis of both drugs in QC laboratories.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmin Mohammed Fayez, Shereen Mostafa Tawakkol, Nesma Mahmoud Fahmy, Mostafa Abdel-Aty Shehata

01/04/2018

Mostafa Abdel-Aty Shehata

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Dalia Mohamed, Mona S. Elshahed

01/01/2018

In the presented work several spectrophotometric methods were performed for the quantification of canagliflozin (CGZ) and metformin hydrochloride (MTF) simultaneously in their binary mixture. Two of these methods; response correlation (RC) and advanced balance point-spectrum subtraction (ABP-SS) were developed and introduced for the first time in this work, where the latter method (ABP-SS) was performed on both the zero order and the first derivative spectra of the drugs. Besides, two recently established methods; advanced amplitude modulation (AAM) and advanced absorbance subtraction (AAS) were also accomplished. All the proposed methods were validated in accordance to the ICH guidelines, where all methods were proved to be accurate and precise. Additionally, the linearity range, limit of detection and limit of quantification were determined and the selectivity was examined through the analysis of laboratory prepared mixtures and the combined dosage form of the drugs. The proposed methods were capable of determining the two drugs in the ratio present in the pharmaceutical formulation CGZ:MTF (1:17) without the requirement of any preliminary separation, further dilution or standard spiking. The results obtained by the proposed methods were in compliance with the reported chromatographic method when compared statistically, proving the absence of any significant difference in accuracy and precision between the proposed and reported methods.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmin MohammedFayez,Shereen MostafaTawakkol,Nesma MahmoudFahmy,Mostafa Abd El-AttyShehataa

01/09/2017

Simultaneous determination of miconazole (MIC), mometasone furaoate (MF), and gentamicin (GEN) in their pharmaceutical combination. Gentamicin determination is based on derivatization with of o-phthalaldehyde reagent (OPA) without any interference of other cited drugs, while the spectra of MIC and MF are resolved using both successive and progressive resolution techniques. The first derivative spectrum of MF is measured using constant multiplication or spectrum subtraction, while its recovered zero order spectrum is obtained using derivative transformation. Beside the application of constant value method. Zero order spectrum of MIC is obtained by derivative transformation after getting its first derivative spectrum by derivative subtraction method. The novel method namely, differential amplitude modulation is used to get the concentration of MF and MIC, while the novel graphical method namely, concentration value is used to get the concentration of MIC, MF, and GEN. Accuracy and precision testing of the developed methods show good results. Specificity of the methods is ensured and is successfully applied for the analysis of pharmaceutical formulation of the three drugs in combination. ICH guidelines are used for validation of the proposed methods. Statistical data are calculated, and the results are satisfactory revealing no significant difference regarding accuracy and precision.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmin M. Fayez, Christine K. Nessim, Adel M. Michael

01/06/2017

Accurate, simple and selective stability-indicating reversed phase HPLC and TLC-densitometric methods with UV detection have been developed and validated for simultaneous determination of chlordiazepoxide (CDZ) and clidinium bromide (CDB) in the presence of its alkali-induced degradation product (DEG). Successful separation of the drugs from the degradation product was achieved. For the RP-HPLC method, the stationary phase was ACE-126-2546 AQ C-18 (250 × 4.6 mm i.d., 5 μm particle size) column at 25 °C, in an isocratic mode, using mobile phase containing a mixture of 25 mM ammonium acetate (pH 5.4): acetonitrile in the ratio of (20:80, v/v), at the flow rate of 1.0 mL min−1 and UV detection was performed at 222 nm. The retention times were (4.13 ± 0.01) and (8.5 ± 0.01) min for CDZ and CDB, respectively. For the TLC-densitometric method, the separation was performed using a stationary phase of precoated Silica Gel G/UV254 and mobile phase composed of a mixture of ethyl acetate: methanol: ammonia (8:3:1, v/v/v) and scanned at 222 nm. The R f values were (0.79 ± 0.02) and (0.11 ± 0.01) for CDZ and CDB, respectively. The linearity graphs for CDZ and CDB, respectively, were found to be linear over (0.5–40) μg mL−1 and (2–45) μg mL−1 with mean percentage recoveries (99.69 ± 0.836) and (99.28 ± 1.838) for RP-HPLC method and (1–14) μg band−1 and (0.5–10) μg band−1 with mean percentage recoveries (100.00 ± 0.782) and (100.19 ± 1.010) for TLC-densitometric method. A comparative study of different analytical validation parameters such as accuracy, precision, specificity and robustness were conducted. The obtained results were statistically compared with those of the official and reported methods; using Student’s t test, F test and one-way ANOVA, showing no significant difference with high accuracy and good precision. The proposed RP-HPLC method was also used to study the kinetics of the alkaline hydrolysis of clidinium bromide that was found to follow pseudo-first order kinetics. The t 1/2 was 8.5729 min while k (the degradation rate constant) was 0.0808353 min−1.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Mowaka, Shereen, Hegazy, Maha A.,Mohamed, Ekram

01/06/2017

Two accurate and sensitive methods were developed and validated for the simultaneous determination of amlodipine (AML), valsartan (VAL), and hydrochlorothiazide (HCT) in their ternary mixture. The first method is a novel simple algorithm capable of extracting the contribution of each component from a mixture signal in which the components are partially or completely overlapped. It is based on the use of a coded function that eliminates the signal of interfering components using mean centering as a processing tool. Determination was performed at 237.6, 250.0, and 270.6 nm for AML, VAL, and HCT, respectively. Two fit values were developed and calculated for optimization of the method for each drug, one to test that the absorptivity values of the extracted spectra are within the confidence limits of the slope, and the other for correlation between the pure and extracted spectra. The fit values for AML, VAL, and HCT were α = 0.0449, 0.03981, and 0.07251, respectively, and r = 1 for each drug. The second method is an ultra-HPLC (UHPLC®) method in which separation of AML, VAL, and HCT was carried out on a UHPLC C18 column (100 × 2.1 mm, 2.2 μm) using a mobile phase of acetonitrile–methanol–phosphate buffer (pH 2.8; 25 + 50 + 25, v/v/v). The flow rate was 0.5 mL/min, and the detection was set at 255.0 nm. The proposed methods were successfully applied to the analysis of AML, VAL, and HCT in pharmaceutical formulations, without interference from the dosage-form additives. The results were statistically compared to a previously reported method, and no significant difference was found regarding accuracy or precision.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Ekram H. Mohamed , Maha A. Hegazy , Shereen Mowaka

01/05/2017

Analysis of complex mixture containing three or more components represented a challenge for analysts. New smart spectrophotometric methods have been recently evolved with no limitation. A study of different novel and smart spectrophotometric techniques for resolution of severely overlapping spectra were presented in this work utilizing isosbestic points present in different absorption spectra, normalized spectra as a divisor and dual wavelengths. A quaternary mixture of drotaverine (DRO), caffeine (CAF), paracetamol (PCT) and para-aminophenol (PAP) was taken as an example for application of the proposed techniques without any separation steps. The adopted techniques adopted of successive and progressive steps manipulating zero /or ratio /or derivative spectra. The proposed techniques includes eight novel and simple methods namely direct spectrophotometry after applying derivative transformation (DT) via multiplying by a decoding spectrum, spectrum subtraction (SS), advanced absorbance subtraction (AAS), advanced amplitude modulation (AAM), simultaneous derivative ratio (S1DD), advanced ratio difference (ARD), induced ratio difference (IRD) and finally double divisor–ratio difference-dual wavelength (DD-RD-DW) methods.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmin Mohammed Fayez Analytical Chemistry Department, Faculty of Pharmacy, Cairo University, Egypt , Shereen Mostafa Tawakkol, Nesma Mahmoud Fahmy , Mostafa Abd El-Atty Shehata

01/04/2017

The mixture of clotrimazole (CLT) and dexamethasone (DA) can be analyzed by resolution of each component separately. First, CLT which has no absorption maxima in its zero order spectrum can be obtained by spectrum subtraction, followed by; the novel mathematical technique two base points or Area under curve to get the concentration, while its resolution to the D1 spectrum by either dual wave length as a resolution technique or derivative subtraction. Second, DA can be obtained in its D° spectrum by constant multiplication coupled ratio subtraction, or its D1 spectrum using constant multiplication coupled derivative subtraction. Direct determination of the less extended CLT from the mixture without resolution is conducted by ratio difference, derivative ratio and induced dual wave length. Simultaneous determination of both components is conducted by Absorbance subtraction and Amplitude modulation. The specificity of the developed methods is checked by analyzing laboratory prepared mixtures and is successfully applied for the analysis of their market formulation. Validation steps are conducted as listed in ICH guidelines and statistically compared to the official methods.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Eman Noaman, Medhat A. Al-Ghobashy , Hayam M. Lotfy

01/12/2016

Fenticonazole (FEN), an imidazole group containing antifungal was subjected to stress conditions; acid and base hydrolysis, photodegradation, thermal decomposition and oxidation. The structure of one major oxidative degradation product was ellucidated using LC-MS/MS.A stability-indicating HPLC assay was developed and validated according to ICH guidelines which enabled the determination of FEN in presence of its degradation product and paraben preservatives (methyl and propyl parabens). Determination was carried out using Zorbax RP-C18-column (5 μm, 15 cm x 4.6 mm i.d.) and gradient elution mode over a concentration range of 10.00-200.00 μg mL⁻¹, 3.50-35.00 μg mL⁻¹ and 1.75-7.50 μg mL⁻¹ for FEN, methyl paraben and propyl paraben, respectively. Column temperature was maintained at 25°C and detection was carried out at 254 nm. As confirmed by the results of HPLC-PDA, FNTI formulations were susciptable to autooxidation. Differentanti-oxidants were tested and results were evaluated following accelerated stability studies (40°C ± 2°C and 75 ±5% relative humidity). Results indicated that using a combination of water soluble and fat soluble antoxidents provided the optimum protection against autooxidation. The reaction was found to follow the zero order reaction kinetics and the KObs and t90% were calculated for each formula.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Hayam M. Lotfy and Sarah S. Saleh

01/11/2016

Several techniques have been proposed for treatment of spectrophotometric data, with the objective of extracting the largest amount of analytical information from spectra composed of unresolved bands. The instrumental development and analytical applications of UV regions absorption spectrophotometry produced in the last 10 y (since 2006) are reviewed. The methods were classified according to the spectra data used, including zero order absorption, derivative and ratio amplitudes. The proposed methods were applied to solve different complex pharmaceutical mixtures and the obtained results were accepted when compared to other reported methods.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmin Mohamde Fayez

01/09/2016

Simple, cost-effective, safe, accurate, precise and environmentally friendly spectro-photometric methods were developed and validated for the quantitative determination of valaciclovir (VAL) in the presence of its related impurity in bulk powder and in its pharmaceutical preparation. This related impurity namely guanine (GUA) is the potential and synthesis impurity of VAL. The spectra of VAL and GUA show the same geometrical features with different absorptivities, so their resolution is very challengeable. A Comparative study was conducted for the results of the conventional methods namely, dual wavelength (DW), first derivative of ratio spectra (1DD) and mean centering of ratio spectra (MCR) versus the recently developed methods namely, induced dual wavelength (IDW), ratio difference (RD) and constant center (CC). The optimized methods allow the estimation of VAL in the concentration range 5-50 μg/mL. The methods were validated as per ICH guidelines and the specificity was assessed by analyzing synthetic mixtures containing different percentages of the related impurity with the drug. The obtained results were compared with that of the official HPLC method by using one-way analysis of variance (ANOVA) and proved to be suitable for quality control laboratories.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Adel Magdy Michael, Yasmin Mohamed Fayez,Christine Kamal Nessim, and Hayam Mahmoud Lotfy

01/09/2016

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Maha A. Hegazy , Hayam M. Lotfy , Shereen Mowaka , Ekram Hany Mohamed

01/08/2016

Hayam Mahmoud Lotfy Ibrahim Mahmoud

01/07/2016

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Hayam.M.Lotfy Shereen Mostafa Tawakkol, Nesma Mahmoud Fahmy, Mostafa Abd El-Atty Shehata

01/07/2016

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Hayam.M.Lotfy ,Maha Abd el-monem Hegazy , Mai m. Abd El-Aziz , Laila Elsayed Abdel Fattah

01/06/2016

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Hayam.M.Lotfy ,Mohamed A. Abdallah and Medhat A. Al-Ghobashy

01/06/2016

Five sensitive, selective and precise stability-indicating spectrophotometric methods for the determination of Sulbutiamine (SUL) in the presence of its alkali-induced degradation product (DEG) were developed and validated. Method A is differential dual wavelength (D1DWL) applied in the analysis of SUL in binary mixture via its first derivative spectra using the difference between two points with equal amplitudes in the alkali-induced degradation product, thus DEG acts as zero contribution. Method B is second derivative spectrophotometry (D2), which allowed the determination of SUL at 300.0 nm. Method C is second derivative of the ratio spectra (DD2) in which SUL was determined by measuring the peak amplitude at 301.0 nm. Method D is the ratio difference spectrophotometry (RD), where the difference between amplitudes of the absorbance ratio spectra at 237.2 and 274.0 nm were recorded and Method E; Ratio subtraction (RSM) where the zero order spectra of pure SUL were extracted from their laboratory prepared mixtures, and consequently SUL can be analyzed at its maxima. The linearity for SUL was obtained within concentrations ranging from 5.00 - 50.00 μg/mL with percentage recovery of 100.58 + 0.98, 99.62 ± 1.16, 100.70 ± 1.38, 100.06 + 1.00 and 99.56 + 1.00 for the five methods, respectively.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Hayam.M.Lotfy , Maha A. Hegazy ,, Shereen Mowaka , Ekram Hany Mohamed

01/03/2016

Wavelets have been adapted for a vast number of signal-processing applications due to the amount of information that can be extracted froma signal. In thiswork, a comparative study on the efficiency of continuouswavelet transform (CWT) as a signal processing tool in univariate regression and a pre-processing tool in multivariate analysis using partial least square (CWT-PLS) was conducted. These were applied to complex spectral signals of ternary and quaternary mixtures.CWT-PLS method succeeded in the simultaneous determination of a quaternary mixture of drotaverine (DRO), caffeine (CAF), paracetamol (PAR) and p-aminophenol (PAP, the major impurity of paracetamol). While, the univariate CWT failed to simultaneously determine the quaternary mixture components and was able to determine only PAR and PAP, the ternary mixtures of DRO, CAF, and PAR and CAF, PAR, and PAP. During the calculations of CWT, different wavelet families were tested. The univariate CWT method was validated according to the ICH guidelines. While for the development of the CWT-PLS model a calibration set was prepared by means of an orthogonal experimental design and their absorption spectra were recorded and processed by CWT. The CWT-PLS model was constructed by regression between the wavelet coefficients and concentration matrices and validation was performed by both cross validation and external validation sets. Both methods were successfully applied for determination of the studied drugs in pharmaceutical formulations.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Amr H. Shendy, Medhat A. Al-Ghobashy, Sohair A. Gad Alla,

01/01/2016

LC–MS/MS assay was developed and validated according to EU guidelines for determination of nitrofuran metabolites and nitroimidazole residues in honey. Crude samples were acid-treated to liberate matrix-bound residues and a modified QuEChERS protocol was employed. Nitrofurantoin, furazolidone, furaltadone and nitrofurazone were determined via analysis of their metabolites AHD, AOZ, AMOZ and SEM, respectively while nitroimidazole residues; ronidazole (RNZ) and dimetridazole (DMZ) were determined directly. For all analytes, neat standard calibration curves, after correction for matrix effect were successfully employed. Decision limit (CCa) and detection capability (CCb) were below the MRPL for nitrofurans (1.00 lg kg1) and the recommended concentration for nitroimidazole (3.00 lg kg1), respectively. The CCa, CCb, percentage recovery and CV% ranges were 0.12–0.74 lg kg1, 0.21–1.27 lg kg1, 90.96–104.80% and 2.65–12.58%, respectively. This work is part of the national initiative for establishing a national monitoring program for drug residues in Egyptian honey.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Maha A. Hegazy, Shereen Mowaka, Ekram Hany Mohamed .

01/01/2016

A comparative study of smart spectrophotometric techniques for the simultaneous determination ofOmeprazole (OMP), Tinidazole (TIN) and Doxycycline (DOX) without prior separation steps is developed. These techniques consist of several consecutive steps utilizing zero/or ratio/or derivative spectra. The proposed techniques adopt nine simple different methods, namely direct spectrophotometry, dual wavelength, first derivative-zero crossing, amplitude factor, spectrumsubtraction, ratio subtraction, derivative ratio-zero crossing, constant center, and successive derivative ratio method. The calibration graphs are linear over the concentration range of 1–20 μg/mL, 5–40 μg/mL and 2–30 μg/mL forOMP, TIN and DOX, respectively. These methods are tested by analyzing synthetic mixtures of the above drugs and successfully applied to commercial pharmaceutical preparation. The methods that are validated according to the ICH guidelines, accuracy, precision, and repeatability, were found to bewithin the acceptable limits.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Yasmin M. Fayez , Adel M.Michael ,, Christine K. Nessim

01/01/2016

Smart, sensitive, simple and accurate spectrophotometric methods were developed and validated for the quantitative determination of a binary mixture of mebeverine hydrochloride (MVH) and chlordiazepoxide (CDZ) without prior separation steps via different manipulating pathways. These pathways were applied either on zero order absorption spectra namely, absorbance subtraction (AS) or based on the recovered zero order absorption spectra via a decoding technique namely, derivative transformation (DT) or via ratio spectra namely, ratio subtraction (RS) coupledwith extended ratio subtraction (EXRS), spectrumsubtraction (SS), constant multiplication (CM) and constant value (CV) methods. The manipulation steps applied on the ratio spectra are namely, ratio difference (RD) and amplitude modulation (AM) methods or applying a derivative to these ratio spectra namely, derivative ratio (DD1) or second derivative (D2). Finally, the pathway based on the ratio spectra of derivative spectra is namely, derivative subtraction (DS). The specificity of the developedmethodswas investigated by analyzing the laboratory mixtures and was successfully applied for their combined dosage form. The proposed methods were validated according to ICH guidelines. These methods exhibited linearity in the range of 2–28 μg/mL for mebeverine hydrochloride and 1–12 μg/mL for chlordiazepoxide. The obtained resultswere statistically compared with those of the official methods using Student t-test, F-test, and one way ANOVA, showing no significant difference with respect to accuracy and precision. ©

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Amr H. Shendy · Medhat A. Al-Ghobashy · Moustapha N. Mohammed · Sohair A. Gad Alla · ·

01/12/2015

Simultaneous Determination of 200 Pesticide Residues in Honey using Gas Chromatography-Tandem Mass Spectrometry in Conjunction with Streamlined Quantification Approach

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Hayam.M.Lotfy , Amr H. Shendya, Medhat A. Al-Ghobashyc,, Moustapha N. Mohammeda,Sohair A. Gad Allaa, ,

01/11/2015

tA sensitive, accurate and reliable multi-class GC–MS/MS assay protocol for quantification and confir-mation of 200 common agricultural pesticides in honey was developed and validated according to EUguidelines. A modified extraction procedure, based on QuEChERS method (quick, easy, cheap, effective,rugged and safe) was employed. Mass spectrophotometric conditions were individually optimized foreach analyte to achieve maximum sensitivity and selectivity in MRM mode. The use of at least two reac-tions for each compound allowed simultaneous identification and quantification in a single run. Thepesticides under investigation were separated in less than 31 min using the ultra-inert capillary column(DB-35MS). For all analytes, neat standard calibration curves in conjunction with correction for matrixeffect were successfully employed. The detection limits of the assay ranged from 1.00 to 3.00 ng mL−1forthe studied pesticides. The developed assay was linear over concentration range of 10.00–500.00 ng mL−1,with correlation coefficient of more than 0.996. At the LOQ, 81% of the studied pesticides were efficientlyrecovered in the range of 70.00–120.00%, with CV% less than 15.00% while 99.3% compounds had meanpercentage recovery of 60.00–140.00%, with CV% less than 21.00% (N = 18, over three different days).The proposed assay was successfully applied for the analysis of the studied pesticide residues in one PTsample and 64 commercial honey samples collected over 1 year from different districts around Egypt.Results revealed that only one honey sample out of the 64 analyzed samples was contaminated withtau-Fluvalinate (10.00 g kg−1). This wide scope assay protocol is applicable for monitoring pesticideresidues in honey by national regulatory authorities and accredited labs; that should help ensure safetyof such widely used product.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

N.Y. Hassan · S.S. Saleh · H. Salem ·

01/01/2015

Membrane selective electrodes were used to determine tetryzoline hydrochloride (TZH) in pure form, pharmaceutical preparations and in biological fluids. The membrane selective electrodes include construction of water insoluble ion-association complexes. The TZH ion exchangers were formed using tetraphenyl borate (TZH-TPB), phosphomolybdic acid (TZH-PMA) and phosphotungstic acid (TZH-PTA), in a plasticized PVC (polyvinyl chloride) matrix, using dibutyl phthalate (DBP) or dioctylphthalate (DOP) as a plasticizer. The performance characteristics of the developed sensors were evaluated according to IUPAC recommendations. The developed sensors showed good responses but the best electrochemical characteristics and selectivity coefficients were achieved with TZH-TPB sensor using DBP as a plasticizer, where the linear responses of TZH was found within the concentration ranges of 10−6 to 10−2 mol/L and Nernstian slope was calculated to be of 56.8 mV/ decade at 25 °C, over the pH range of 5–9. The suggested method was used to determine TZH in synthetic mixtures, pharmaceutical formulations and in presence of its alkali degradation product. The proposed sensors displayed useful analytical characteristics for the determination of TZH in biological fluids such as rabbit aqueous humor and human plasma. The later application can be used to detect oral TZH poisoning in children. The obtained results were statistically compared with the official method, showing no significant difference with respect to accuracy and precision.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Dalia Mohamed, Shereen Mowaka.

01/01/2015

Simple, specific, accurate and precise spectrophotometric methods were developed and validated for the simultaneous determination of the oral antidiabetic drugs; sitagliptin phosphate (STG) and metformin hydrochloride (MET) in combined pharmaceutical formulations. Three methods were manipulating ratio spectra namely; ratio difference (RD), ratio subtraction (RS) and a novel approach of induced amplitude modulation (IAM) methods. The first two methods were used for determination of STG, while MET was directly determined by measuring its absorbance at kmax 232 nm. However, (IAM) was used for the simultaneous determination of both drugs. Moreover, another three methods were developed based on derivative spectroscopy followed by mathematical manipulation steps namely; amplitude factor (P-factor), amplitude subtraction (AS) and modified amplitude subtraction (MAS). In addition, in this work the novel sample enrichment technique named spectrum addition was adopted. The proposed spectrophotometric methods did not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined. The selectivity of the developed methods was investigated by analyzing laboratory prepared mixtures of the drugs and their combined pharmaceutical formulations. Standard deviation values were less than 1.5 in the assay of raw materials and tablets. The obtained results were statistically compared to that of a reported spectrophotometric method. The statistical comparison showed that there was no significant difference between the proposed methods and the reported one regarding both accuracy and precision.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Sawsan M. Amer, Hala E. Zaazaa, Noha S. Mostafa

01/01/2015

Two novel simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra are developed and validated for simultaneous determination of Esomeprazole magnesium trihydrate (ESO) and Naproxen (NAP) namely; absorbance subtraction and ratio difference. The results were compared to that of the conventional spectrophotometric methods namely; dual wavelength and isoabsorptive point coupled with first derivative of ratio spectra and derivative ratio. The suggested methods were validated in compliance with the ICH guidelines and were successfully applied for determination of ESO and NAP in their laboratory prepared mixtures and pharmaceutical preparation. No preliminary separation steps are required for the proposed spectrophotometeric procedures. The statistical comparison showed that there is no significant difference between the proposed methods and the reported method with respect to both accuracy and precision

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Amer SM, Zaazaa HE and Mostafa NS

01/01/2015

Simple, accurate, sensitive and precise UV spectrophotometric methods were developed and validated for quantitative determination of binary mixture of Naproxen sodium (NAP) and Domperidone maleate (DOM) in their bulk powder and pharmaceutical dosage forms. NAP was determined in presence of DOM by direct spectrophtometry at λmax 331 nm. Four spectrophotometric methods, namely; isoabsorptive point (I), ratio subtraction (II), ratio difference (III) and mean centering (IV) were developed for the spectral resolution of DOM when present in mixture with NAP without preliminary separation. In method (I), the isoabsorptive point (Aiso) at 274.7nm was chosen for determination of DOM while in method (II), DOM was determined at λmax 287 nm after subtraction of interference exerted by NAP. In method (III), absorption spectra of DOM were recorded, divided by suitable divisor of NAP then measuring the absorption difference at 280 and 294 nm to obtain the corresponding concentrations of DOM. In method (IV), absorption spectra of each drug were recorded, DOM spectra were divided by suitable divisor of NAP and the obtained ratio spectra were mean centered. The concentrations of DOM was then determined from the calibration graphs obtained by measuring amplitudes at 295nm. The developed methods were validated according to ICH guidelines demonstrating good accuracy and precision.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Sarah S. Saleh, , Nagiba Y. Hassan, Hesham Salem

01/01/2015

Novel spectrophotometric methods were applied for the determination of the minor component tetryzoline HCl (TZH) in its ternary mixture with ofloxacin (OFX) and prednisolone acetate (PA) in the ratio of (1:5:7.5), and in its binary mixture with sodium cromoglicate (SCG) in the ratio of (1:80). The novel spectrophotometric methods determined the minor component (TZH) successfully in the two selected mixtures by computing the geometrical relationship of either standard addition or subtraction. The novel spectrophotometric methods are: geometrical amplitude modulation (GAM), geometrical induced amplitude modulation (GIAM), ratio H-point standard addition method (RHPSAM) and compensated area under the curve (CAUC). The proposed methods were successfully applied for the determination of the minor component TZH below its concentration range. The methods were validated as per ICH guidelines where accuracy, repeatability, inter-day precision and robustness were found to be within the acceptable limits. The results obtained from the proposed methods were statistically compared with official ones where no significant difference was observed. No difference was observed between the obtained results when compared to the reported HPLC method, which proved that the developed methods could be alternative to HPLC techniques in quality control laboratories

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Adel M. Michael, Mamdouh R. Rezk and Mostafa A. Shehata

01/01/2015

This work describes comparative study of multivariate chemometric and univariate spectrophotometric determination of zolmitriptan (ZLM ) in the presence of its alkaline and oxidative degradation products. Both methods show high sensitivity and the same linearity range (1-6 μg/mL) while the chemometric method has the advantage of higher accuracy, higher specificity and better regression parameters. The study describes complete stability study on zolmitriptan and structure elucidation of the formed degradation products. The spectrophotometric method based on successive spectrophotometric resolution pattern namely; successive ratio subtraction (SRS) method using both degradation products as divisors successively followed by direct spectrophometric measurement of zolmitriptan at 222 nm while the chemometric method used PLS and PCR models. The proposed methods were successfully applied for the determination of zolmitriptan in pure powder as well as in its pharmaceutical formulation. Statistical comparison showed no significant difference between the developed methods and the reference method.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Eman G. Noumana, Medhat A. Al-Ghobashy

01/01/2015

tDabigatran etexilate (DABE) is a low-molecular-weight prodrug that is converted after oral adminis-tration to dabigatran (DAB)—a directly acting oral anticoagulant. In this study, an LC–MSMS assay wasdeveloped and validated for the determination of DABE, free DAB and its equipotent O-glucuronide con-jugates in plasma. Owing to the susceptibility of DABE and DAB to chemical hydrolysis, cleavage of theO-glucuronide moiety was carried out using -glucuronidase enzyme. Free and total plasma concentra-tions of DAB were determined in incurred plasma samples before and after enzymatic cleavage (50◦Cand 3 h), respectively. RP-HPLC separation was carried out using acetonitrile: water (30:70, v/v), adjustedto pH 3.0 using formic acid. Tandem mass spectrometric detection at positive electrospray ionization inthe MRM mode was then employed for the determination of DABE and DAB. The analysis was carriedout within 5.0 min over a linear concentration range of 1.00–600.00 ng/mL for the prodrug and its activemetabolite. Validation was carried out according to FDA guidelines for bioanalytical method. The recov-eries were higher than 89.48%, the accuracy was within 98.33–110.12% and the RSD was below 10% forthe studied compounds in both incurred plasma and quality control samples. Results of incurred samplere-analysis and incurred sample stability revealed less than 10% variability. This indicated good assayprecision and sufficient stability of target analytes in their real matrix at the employed experimentalconditions. The applicability of the assay for therapeutic drug monitoring and the determination of thepharmacokinetic parameters were demonstrated

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Maha A. Hegazy, Mamdouh R. Rezk, Yasmin Rostom Omran

01/01/2015

Smart spectrophotometric methods have been applied and validated for the simultaneous determination of a binary mixture of chloramphenicol (CPL) and prednisolone acetate (PA) without preliminary separation. Two novel methods have been developed; the first method depends upon advanced absorbance subtraction (AAS), while the other method relies on advanced amplitude modulation (AAM); in addition to the well established dual wavelength (DW), ratio difference (RD) and constant center coupled with spectrum subtraction (CC–SS) methods. Accuracy, precision and linearity ranges of these methods were determined. Moreover, selectivity was assessed by analyzing synthetic mixtures of both drugs. The proposed methods were successfully applied to the assay of drugs in their pharmaceutical formulations. No interference was observed from common additives and the validity of the methods was tested. The obtained results have been statistically compared to that of official spectrophotometric methods to give a conclusion that there is no significant difference between the proposed methods and the official ones with respect to accuracy and precision.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Sarah S. Saleh, and Hesham Salem,Nagiba Y. Hassan

01/01/2015

Membrane selective electrodes were used to determine tetryzoline hydrochloride (TZH) in pure form, pharmaceutical preparations and in biological fluids. The membrane selective electrodes include construction of water insoluble ion-association complexes. The TZH ion exchangers were formed using tetraphenyl borate (TZH-TPB), phosphomolybdic acid (TZH-PMA) and phosphotungstic acid (TZH-PTA), in a plasticized PVC (polyvinyl chloride) matrix, using dibutyl phthalate (DBP) or dioctylphthalate (DOP) as a plasticizer. The performance characteristics of the developed sensors were evaluated according to IUPAC recommendations. The developed sensors showed good responses but the best electrochemical characteristics and selectivity coefficients were achieved with TZH-TPB sensor using DBP as a plasticizer, where the linear responses of TZH was found within the concentration ranges of 10−6 to 10−2 mol/L and Nernstian slope was calculated to be of 56.8 mV/ decade at 25 °C, over the pH range of 5–9. The suggested method was used to determine TZH in synthetic mixtures, pharmaceutical formulations and in presence of its alkali degradation product. The proposed sensors displayed useful analytical characteristics for the determination of TZH in biological fluids such as rabbit aqueous humor and human plasma. The later application can be used to detect oral TZH poisoning in children. The obtained results were statistically compared with the official method, showing no significant difference with respect to accuracy and precision.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Hesham Salem, Nagiba Y. Hassan and Sarah S. Saleh

01/01/2015

This work presents a comparative study on the development and validation of two analytical techniques applied for the simultaneous determination of hydrocortisone acetate (HCA), fusidic acid (FSA), methyl paraben (MPB), and propyl paraben (PPB) formulated as a topical cream. The first technique was thin-layer chromatography (TLC)–densitometric method, which was developed by separating the four components on silica gel 60 F254 using methylene chloride–methanol–benzene in the ratio of 10:2:5, v/v, as the developing system, followed by densitometric measurement of the bands at 240 nm. The second technique was the chemometric method using two models: principle component regression model (PCR) and partial least squares (PLS). The suggested techniques were validated in compliance with the International Conference on Harmonization (ICH) guidelines and were successfully applied for the determination of the quaternary mixtures as prepared synthetically in laboratory and in the commercial topical pharmaceutical formulation.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Mamdouh R Rezk · Adel M Michael · Hayam M Lotfy · Mostafa A Shehata

01/12/2013

A novel sumatriptan (SUM) selective electrode was investigated with dioctyl phthalate as a plasticizer in a polymeric matrix of carboxylated polyvinyl chloride (PVC-COOH), based on the interaction between the drug solution and the dissociated COOH groups in the PVC-COOH. The sensor was fabricated by using PVC-COOH only as anionic site without incorporation of an ionophore. Linear response of SUM within a concentration range of 10 -6 -10 -3 M with a slope of 34±1 mV/decade over pH range of 6-8 was observed. The measurement was characterized by a fast stable response within about 45 seconds.The proposed sensor was successfully applied for the selective determination of sumatriptanin the pure powder form and in its pharmaceutical formulation with naproxen without any interference. The results obtained by the proposed procedure were statistically analyzed and compared with those obtained by the U.S. Pharmacopeia method. No significant difference for either accuracy or precision was observed.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

A.M. Mohsen · H.M. Lotfy · A.M. Badawey · H. Salem · S.Z. Elkhateeb ·

01/01/2013

Three spectrophotometric methods are presented for the determination of a binary mixture of Chlorphenoxaminehydrochloride (CPX) and Caffeine (CAF) in laboratory prepared mixture and pharmaceutical dosage form without prior separation. Method (I)is an extended ratio subtraction method (EXRSM) coupled with ratio subtraction method (RSM), which depends on subtraction of the plateau values from the ratio spectrum. Method (II)is a ratio difference spectrophotometric method (RDSM), which depends on the difference in value between two different wavelengths of the ratio spectrum. Method (III) is a mean centering of ratio spectra (MCR). Mathematical explanation of the three methods is illustrated. Calibration curves of the three methods are linear over the concentration ranges of 4-24 μgml-1and 2-24 μgml-1for CPX and CAF, respectively.The three methods proved to be simple, specific, accurate and precise. Solvent used is double distilled water. The three methods are validated as per the ICH guidelines where accuracy, precision, repeatability and robustness are found to be within the acceptable limits.

Hayam Mahmoud Lotfy Ibrahim Mahmoud

Mostafa A. Shehata · Hayam M. Lotfy · Mamdouh R. Reda · Karim Michail · Vishwa Somayaji · Adel M.Michael ·

01/12/2012

This work describes a simple and sensitive method for the concurrent determination of sumatriptan (SUM) and naproxen (NAP) in dosage forms and human plasma using LC/MS and internal standardization. The drugs were separated isocratically on a C 18 column using a binary mobile phase composed of water and acetonitrile at 0.05 % acetic acid. The method was validated over a linearity range of 10-900 ng/mL and 0.1-10 μg/mL for SUM and NAP, respectively. The LOQ for SUM and NAP were 10 and 100 ng/mL, respectively. The proposed method was successfully used for the determination of SUM and NAP in plasma after a double liquid liquid extraction (LLE). The assay was successfully applied to the determination of both drugs in pharmaceutical dosage forms without interference from tablet excipients. Results obtained by the proposed method were statistically compared to those of a reported method, and no significant difference was observed