A rapid, simple and highly sensitive first derivative synchronous fluorometric method has been developed for the simultaneous analysis of binary mixture of sulpiride (SUL) and mebeverine hydrochloride (MEB). The method is based upon measurement of the synchronous fluorescence intensity of these drugs at ∆λ = 100 nm in water. The different experimental parameters affecting the fluorescence of the two drugs were carefully studied and optimized. The fluorescence-concentration plots were rectilinear over the range of 0.05-1 µg/mL and 0.2-3.2 µg/mL for SUL and MEB respectively with lower detection limits (LOD) of 0.006 and 0.01 µg/mL and quantification limits (LOQ) of 0.0.02 and 0.05 µg/mL for SUL and MEB, respectively. The proposed method was successfully applied for the determination of the two compounds in synthetic mixtures and in commercial tablets. The high sensitivity attained by the proposed method allowed the determination of both of SUL and MEB metabolite (veratic acid) in real human plasma samples applying second derivative synchronous fluorometric technique. The mean% recoveries (n = 3) for both MEB metabolite (veratic acid) and SUL were 99.82 ± 2.53 and 98.84 ± 6.20 for spiked human plasma respectively, while for real human plasma, the mean% recoveries (n = 3) were 91.49 ± 4.25 and 91.36 ± 8.46 respectively.

A highly sensitive, simple and rapid spectrofluorimetric method was developed for the determination of lacidipine (LCP) in tablets. The proposed method is based on the investigation of the fluorescence spectral behavior of LCP in both sodium dodecyl sulphate (SDS) and the tween-80 micellar system. In aqueous solutions of acetate buffer (pH 4.5), the fluorescence intensities of LCP were greatly enhanced (ca. 2.4 and 4.3 folds) in the presence of either SDS or tween-80, respectively. The fluorescence intensity was measured at 444 nm after excitation at 277 nm using either SDS or tween-80 as a surfactant. The fluorescence-concentration plots were rectilinear over the ranges of 50.0-500.0 ng/ml and 5.0-200.0 ng/ml with lower detection limits of 5.11 and 2.06 ng/ml and lower quantification limits of 17 and 6.87 ng/ml using SDS and tween-80, respectively. The method was successfully applied to the analysis of LCP in commercial tablets and the results were in good agreement with those obtained with the comparison method. Furthermore, content uniformity testing of pharmaceutical tablets was also conducted.

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A spectrophotometric method for the determination of three nitro derivatives, namely, oxamniquine, nitrazepam and chloramphenicol, is described. The proposed method involves reduction of the analyte with Zn -HCI followed by diazotisation and coupling of the resulting diazonium salt with ethyl acetoacetate in alkaline medium. The stoicheiometry of the reaction was assessed and a possible reaction pathway is presented. The nominal recovery of the drugs from pharmaceutical preparations ranges from 98.78 & 0.51 to 100.96 k 0.81%. The method is simple, sensitive and applicable to unit dose analysis.

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A new simple, rapid and sensitive reversed-phase liquid chromatographic method was developed and validated for the simultaneous determination of ascorbic acid (ASC) and salicylamide (SAL) in their combined dosage form. The analysis was carried out on CLC Shim-pack C 8 column (250 x 4.6 mm, 5 µm particle size) using a mobile phase consisting of methanol: 0.03 M phosphate buffer mixture (55: 45, v/v) of pH 4.0. The mobile phase was pumped at a flow rate of 1 mL/min with ultraviolet detection at 255 nm. The selectivity, linearity of calibration, accuracy, intra and inter day precision and recovery were examined as parts of the method validation. The concentrationresponse relationship was linear over a concentration range of 0.50-10.00 and 5.00-50.00 µg/mL for ASC and SAL, respectively with limits of detection of 0.048 and 0.676 µg/mL. The proposed method was applied for the simultaneous determination of the two studied drugs in their combined tablets with average recoveries of 100.04 ± 0.75% and 100.11 ± 1.04% for ASC and SAL, respectively. The results were favorably compared to those obtained by the comparison methods.

A new simple, rapid and sensitive reversed‐phase liquid chromatographic method was developed and validated for the simultaneous determination of methocarbamol (MET) and aspirin (ASP) in their combined dosage form. The separation of these compounds was achieved within 6.0 min on a CLC Shim‐pack C8 column (250 × 4.6 mm, 5 µm particle size) using isocratic mobile phase consisting of acetonitrile and 0.02 M dihydrogenphosphate buffer (30:70, v/v) at pH = 5.0. The analysis was performed at a flow rate of 1.0 mL/min with fluorescence detection at 277/313 nm for MET and 298/410 nm for ASP using real‐time programming. The selectivity, linearity of calibration, accuracy, inter‐ and intra‐day precision and recovery were examined as parts of the method validation. The concentration–response relationship was linear over concentration ranges of 0.02‐0.20 and 0.02‐0.40 µg/mL for MET and ASP, respectively, with a limit of detection of 6 and 32 ng/mL for MET and ASP, respectively. The proposed method was successfully applied for the analysis of both MET and ASP in prepared tablets with average recoveries of 99.88 ± 0.65% for MET and 100.44 ± 0.78% for ASP. The results were favourably compared to those obtained by a reference method. Copyright © 2012 John Wiley & Sons, Ltd.