Yasser S. El-Saharty

Antioxidant activity of extracts from roasted wheat germ

Solvents extracts of roasted wheat germ, an actual waste stream of wheat processing, retarded the autoxidation of corn oil stored at 60°C. Best stabilisation of stripped corn oil was obtained with an ethanolic extract (antioxidative extract, AOE) from wheat germ that was roasted at 160°C for 20 min. Even high dosages of 20 and 40% AOE did not show prooxidative effects. Using accelerated ageing of commercial plant oils, and peroxide value, conjugated diene hydroperoxide concentration and α-tocopherol concentration as analytical indicators, a significant improvement of storability was demonstrated for each oil. Results indicate the presence of classes I and II antioxidants in ethanolic AOE of wheat germ.

Stability-indicating spectrophotometric and densitometric methods for determination of aceclofenac.

ABSTRACT Three methods were developed for the determination of aceclofenac in the presence of its degradation product, diclofenac. In the first method, third-derivative spectrophotometry (D3) is used. The D3 absorbance is measured at 283 nm where its hydrolytic degradation product diclofenac does not interfere. The suggested method shows a linear relationship in the range of 4–24 µg mL−1 with mean percentage accuracy of 100.05±0.88. This method determines the intact drug in the presence of up to 70% degradation product with mean percentage recovery of 100.42±0.94. The second method depends on ratio-spectra first-derivative (RSD1) spectrophotometry at 252 nm for aceclofenac and at 248 nm for determination of degradation product over concentration ranges of 4–32 µg mL−1 for both aceclofenac and diclofenac with mean percentage accuracy of 99.81±0.84 and 100.19±0.72 for pure drugs and 100.17±0.94 and 99.73±0.74 for laboratory-prepared mixtures, respectively. The third method depends on the quantitative evaluation of thin-layer chromatography of aceclofenac using chloroform:methanol: ammonia (48:11.5:0.5 v/v/v) as a mobile phase. Chromatograms were scanned at 274 and 283 nm for aceclofenac and diclofenac, respectively. The method determined aceclofenac and diclofenac in concentration ranges of 2–10 and 1–9 µg spot−1 with mean percentage accuracy of 100.20±1.03 and 100.14±0.98 for pure drugs and 99.77±0.74 and 100.07±0.78 for laboratory-prepared mixtures, respectively. This method retains its accuracy in the presence of up to 80% degradation product for the studied drug. The suggested procedures were checked using laboratory-prepared mixtures and were successfully applied for the analysis of their pharmaceutical preparation. The validity of the proposed methods was further assessed by applying a standard addition technique. The obtained results agreed statistically with those obtained by the reported method.

Simultaneous determination of terbinafine HCL and triamcinolone acetonide by UV derivative spectrophotometry and spectrodensitometry

A binary mixture of terbinafine hydrochloride and triamcinolone acetonide was determined by three different methods. The first one concerned with determination of both drugs using first derivative (D(1)) spectrophotometric technique at 297 and 274 nm over concentration ranges of 5-30 and 4-24 microg ml(-1), with mean percentage accuracies 99.90+/-0.67 and 100.25+/-0.49, respectively. The second method depends on ratio-spectra 1st derivative (RSD(1)) spectrophotometry at 298 and 248 nm over the same concentration ranges with mean percentage accuracies 100.22+/-0.51 and 99.93+/-0.56, respectively. The spectrodensitometric analysis provides a rapid and precise method for the separation and quantitation of both terbinafine hydrochloride and triamcinolone acetonide. The method depends on the quantitative densitometric evaluation of thin layer chromatogram of terbinafine hydrochloride and triamcinolone acetonide at 283 and 238 nm over concentration ranges of 5-25 and 2.5-22.5 microg spot(-1), with mean percentage accuracies 100.66+/-0.51 and 100.27+/-0.73, respectively. The suggested procedures were checked using laboratory prepared mixtures and were successfully applied for the analysis of their pharmaceutical preparations. The three methods retained their accuracy and precision when applying the standard addition technique. The results obtained by applying the proposed methods were statistically analysed and compared with those obtained by a reported method.

Development of membrane electrodes for the selective determination of hyoscine butylbromide

Four polyvinyl chloride (PVC) membrane sensors for the determination of hyoscine butylbromide are described and characterized. The sensors are based on the use of the ion association complexes of hyoscine cation with ammonium reineckate counter anions as ion exchange sites in the PVC matrix. The membranes incorporate ion association complexes of hyoscine with dibutylsebathete (sensor 1), dioctylphthalate (sensor 2), nitrophenyl octyl ether (sensor 3) and beta-cyclodextrin (sensor 4). The performance characteristics of these sensors were evaluated according to IUPAC recommendations, which reveal a fast, stable and linear response for hyoscine over the concentration range of 10(-5)-10(-2)M for sensors 1 and 2 and 10(-6)-10(-2) for sensors 3 and 4 with cationic slopes of -53.19, -55.17, -51.44 and -51.51mV per concentration decade for the four sensors, respectively. The direct potentiometric determination of hyoscine butylbromide using the proposed sensors gave average recoveries % of 99.92+/-1.11, 99.93+/-1.00, 99.94+/-1.18 and 99.87+/-1.39 for the four sensors, respectively. The sensors are used for determination of hyoscine butylbromide in laboratory prepared mixtures, pharmaceutical formulations in combination with ketoprofen and in plasma. Validation of the method shows suitability of the proposed sensors for use in the quality control assessment of hyoscine butylbromide. The developed method was found to be simple, accurate and precise when compared with a reported HPLC method.

Preparation and characterization of pH-responsive polyacrylamide molecularly imprinted polymer: Application to isolation of recombinant and wild type human serum albumin from biological sources.

In this work pH-responsive neutral and cationic polyacrylamide molecularly imprinted polymers (nMIP and cMIP, respectively) were prepared for separation of recombinant and wild type human serum albumin (HSA, pI 4.7) using mixture of polymerization initiators. The effect of pH during preparation and adsorption stages at pI(HSA)±2.0 on binding capacity and selectivity; imprinting factor (IF) was thoroughly investigated. SE-HPLC and RP-HPLC were employed for thorough evaluation of the stability of HSA at the studied experimental conditions and for simultaneous determination of HSA and erythropoietin (EPO) in their mixtures, respectively. Results showed that nMIP were generally superior to cMIP, where nMIP prepared at pH 2.7 and tested at pH 6.7 showed superior binding characteristics (IF 42.91). The pH at the preparation stage imposed minimal effect on the stability of HSA owing to entrapment of HSA within the polymer network. Adsorption experiments carried out at pH 2.7, regardless of polymer type and pH of preparation revealed poor selectivity. Adsorption of HSA onto MIP followed Sips model with pseudo second-order kinetics. Scanning electron microscopy (SEM) revealed a rough surface for MIP and a smooth one with wider pore diameter for non-imprinted polymer (NIP). Successful separation of recombinant HSA from its binary mixture with EPO and wild type HSA from crude plasma was demonstrated using RP-HPLC. This suggested that MIP should be applicable for downstream purification of therapeutic grade HSA at scale either from plasma or recombinant sources and isolation of HSA from plasma for diagnostic purposes.

Qualitative and Quantitative Chemometry as Stability-Indicating Methods for Determination of Dantrolene Sodium and Paracetamol

Methods and Result: Three stability indicating chemometric methods are applied for the simultaneous determination of Dantrolene sodium (DNT) and Paracetamol (PAR). Partial Least Squares (PLS), Concentration Residuals Augmented Classical Least Squares (CRACLS) and Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) were selected for that purpose. DNT and PAR were determined in the linearity range of (2 – 10 g mL) and (12 – 28 g mL), respectively, in the presence of their degradation products. The presented methods were compared for their qualitative and quantitative analyses and validated according to the ICH guidelines. Furthermore, statistical comparison between the results obtained by the proposed methods and the reported chromatographic method showed no significant differences.