A simple, fast, sensitive and stability-indicating derivative spectrofluorimetric method is presented for the assay of zopiclone (ZOP), a drug with hypnotic effect, and its main degradation product and major contaminant,... more
A simple, fast, sensitive and stability-indicating derivative spectrofluorimetric method is presented for the assay of zopiclone (ZOP), a drug with hypnotic effect, and its main degradation product and major contaminant, 2-amino-5-chloropyridine (ACP). The method is based on measuring the inherent fluorescence intensity of both drugs at λex=300nm in methanol, then differentiation using D1 (first derivative technique). The developed method was found to be rectilinear over a range of 0.2-4μg/mL of ZOP and 4-100ng/mL of ACP. The limits of detection were 0.05μg/mL of ZOP and 0.2ng/mL of ACP with the limit of quantitation of 0.17μg/mL of ZOP and 0.7ng/mL of ACP. The outcoming results of the proposed method were compared to those obtained by a reference method showing no significant statistical difference between them concerning precision and accuracy. Additionally, the developed method was applied for detecting ACP in spiked human urine and plasma specimens as a tool of clinical evidence of zopiclone intake that can be easily implemented in forensic laboratories. The proposed method was validated as per ICH guidelines.
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Three different spectrophotometric and two spectrofluorimetric methods have been developed and validated for the determination of vincamine (VN) and naftidrofuryl oxalate (NF) in tablets. The spectrophotometric methods depend on charge... more
Three different spectrophotometric and two spectrofluorimetric methods have been developed and validated for the determination of vincamine (VN) and naftidrofuryl oxalate (NF) in tablets. The spectrophotometric methods depend on charge transfer complex formation between each of VN and NF with 7,7,8,8-tetracyano-quinodimethane (TCNQ), 2,6-dichloroquinone-4-chloroimide (DCQ) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) at 843, 580 and 588 nm, respectively. The spectrofluorimetric methods are based on the formation of charge transfer complex between each of the two drugs and TCNQ, with measurement of the fluorophore formed at 312/375 and 284/612 nm, respectively, or with DDQ at 400/475 and 284/396 nm, respectively. In the spectrophotometric measurements, Beer's law was obeyed at concentration ranges of 1.5-16, 10-180 and 12-140 μg/ml for VN with TCNQ, DCQ, and DDQ, respectively. For NF, the corresponding concentrations were 2-28, 5-75 and 25-150 μg/ml with TCNQ, DCQ, and DDQ, respectively. In the spectrofluorimetric measurements, the ranges for VN were 0.05-0.9 and 0.3-4 μg/ml with TCNQ and DDQ, respectively, whereas for NF the ranges were 0.05-0.85 and 0.5-8 μg/ml with TCNQ and DDQ, respectively. The different experimental parameters affecting the development and stability of the formed color or fluorophore were studied and optimized and the molar ratios of the complexes were calculated. The proposed methods were validated according to ICH guidelines and were successfully applied for the determination of VN and NF in their tablet dosage forms.
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Two simple, rapid and sensitive methods, namely, fourth-derivative synchronous spectrofluorimetry (method I) and HPLC with fluorescence detection (method II) were developed for the simultaneous analysis of a binary mixture of itopride HCl... more
Two simple, rapid and sensitive methods, namely, fourth-derivative synchronous spectrofluorimetry (method I) and HPLC with fluorescence detection (method II) were developed for the simultaneous analysis of a binary mixture of itopride HCl (ITP) and domperidone (DOM) without prior separation. The first method was based on measuring the fourth derivative of the synchronous fluorescence spectra of the two drugs at Δλ = 40 nm in methanol. The different experimental parameters affecting the synchronous fluorescence of the studied drugs were carefully optimized. Chromatographic separation was performed in < 6.0 min using a RP C18 column (250 mm × 4.6 mm i.d., 5 µm particle size) with fluorescence detection at 344 nm after excitation at 285 nm. A mobile phase composed of a mixture of 0.02 M phosphate buffer with acetonitrile in a ratio of 55 : 45, pH 4.5, was used at a flow rate of 1 mL/min. Linearity ranges were found to be 0.1-2 µg/mL for ITP in both methods, whereas those for DOM were found to be 0.08-2 and 0.05-1.5 µg/mL in methods I and II, respectively. The proposed methods were successfully applied for the determination of the studied drugs in synthetic mixtures and laboratory-prepared tablets. Copyright © 2015 John Wiley & Sons, Ltd.
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Piroxicam is a drug with analgesic and anti-inflammatory properties. It is present in numerous pharmaceutical preparations. Injectable forms usually contain benzyl alcohol as an excipient, which is used as a blocking anesthetic (4%) and... more
Piroxicam is a drug with analgesic and anti-inflammatory properties. It is present in numerous pharmaceutical preparations. Injectable forms usually contain benzyl alcohol as an excipient, which is used as a blocking anesthetic (4%) and an antiseptic (4-10%). In this work, spectrophotometric methodology was used in order to determine benzyl alcohol in piroxicam injectable formulations by applying the fourth derivative method adopting the zero-crossing technique. The results obtained show that the method has significant advantages over other reported methods and is appropriate for routine pharmaceutical analysis. The method showed excellent linearity in the range of 2-100 �gmL-1 with limit of detection (S/N = 3) 0.07 �g mL-1 (6.47 � 10-7 M). The proposed method could be applied successfully for the determination of benzyl alcohol in injectable formulations with average % recovery of 100 � 0.61.
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A simple and reliable HPLC method was developed and validated for the simultaneous determination of the hypnotic drug, zopiclone (ZPC) and its degradation product and main impurity, 2-amino-5-chloropyridine (ACP). The analyses were... more
A simple and reliable HPLC method was developed and validated for the simultaneous determination of the hypnotic drug, zopiclone (ZPC) and its degradation product and main impurity, 2-amino-5-chloropyridine (ACP). The analyses were carried out on BDS Hypersil phenyl column (4.6 mm × 250 mm, 5 μm particle size) using micellar mobile phase consisting of 0.15M SDS, 10% n-propanol, 0.3% triethylamine, and 0.02 M orthophosphoric acid (pH 3.5) with timed programmable fluorescence detection. The proposed method was found to be rectilinear over the concentration ranges of 0.5-10.0 μg/mL for ZPC and 2.5-50 ng/mL for ACP. Moreover, the method was applied for the determination of ZPC in commercial tablets with mean percentage recovery of 99.06±1.49. The results of the proposed method were statistically compared with those obtained by the comparison method revealing no significance differences in the performance of the two methods regarding accuracy and precision. Furthermore, the proposed method was applied for the detection and determination of ACP in human urine as a marker for ZPC intake.
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ABSTRACT A simple, sensitive and rapid micellar HPLC method was optimized and validated for the analysis of amoxicillin and ampicillin residues in food samples. Analytical separation was performed in less than 7 min using a RP C18 column... more
ABSTRACT A simple, sensitive and rapid micellar HPLC method was optimized and validated for the analysis of amoxicillin and ampicillin residues in food samples. Analytical separation was performed in less than 7 min using a RP C18 column with UV detection at 220 nm and a micellar solution of 0.05 M sodium dodecyl sulphate, 5% 1-propanol and 0.3% triethylamine in 0.02 M phosphoric acid buffered at pH 5 as the mobile phase. The flow rate was 1 mL min−1 and the effluent was monitored at 220 nm. The micellar method was successfully applied to quantitatively determine amoxicillin and ampicillin residues in spiked chicken muscles, chicken liver, bovine muscles, liver, kidney and eggs. The method was fully validated in accordance with ICH guidelines. Linearity was in the range 0.4–20 μg mL−1 for each drug and the percentage recoveries of both drugs ranged from 95.5 to 102.3% for amoxicillin and 95.6 to 101.7% for ampicillin. High extraction efficiency of amoxicillin and ampicillin was obtained without matrix interference in the extraction process and in the subsequent chromatographic determination. An aqueous solution of SDS surfactant only was used in extraction. No organic solvent was used during the pretreatment step. Hence, it is considered an interesting technique for “green” chemistry.
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A stability‐indicating reversed‐phase high performance liquid chromatographic method was developed for the analysis of the antipsychotic drug quetiapine. Quetiapine was determined in presence of two of its degradation products; quetiapine... more
A stability‐indicating reversed‐phase high performance liquid chromatographic method was developed for the analysis of the antipsychotic drug quetiapine. Quetiapine was determined in presence of two of its degradation products; quetiapine N‐oxide and quetiapine lactam. The analysis was carried out using a 250 mm×4.6 mm i.d., 5 µm particle size Zorbax SB‐Phenyl column. Mobile phase containing a mixture of acetonitrile and 0.02 M phosphate buffer (50∶50) at pH=5.5 was pumped at a flow rate of 1 mL/min with UV detection at 254 nm. The method showed good linearity in the range of 0.08–20 µg/mL with limit of detection (S/N=3) 0.03 µg/mL (3.3×10 M). The suggested method was successfully applied for the analysis of quetiapine in bulk, tablets, and human plasma with average recoveries of 99.96±1.25%, 101.37±0.481%, and 100.82±1.53%, respectively. The proposed method was also applied for the determination of quetiapine in the presence of some co‐administered drugs as clomipramine, carbamazep...