Determination of the carboxylic acid metabolite of clopidogrel in human plasma by liquid chromatography-electrospray ionization mass spectrometry

A rapid and specific liquid chromatographic-mass spectrometric method has been developed and validated for the determination of the carboxylic acid metabolite of clopidogrel in human plasma. Sulphafurazole was used as internal standard. The samples were subjected to a solid phase extraction procedure using Hypercarb cartridges. The chromatographic separation was performed on a reversed phase porous graphitized carbon column using a mobile phase consisting of 70% methanol in water containing 0.1% (v/v) trifluoroacetic acid, pumped at a flow rate of 0.25mlmin-1. The analytes were detected after positive electrospray ionization using the selected ion monitoring mode of the species at m/z 308 for the carboxylic acid metabolite of clopidogrel, m/z 322 for clopidogrel and m/z 268 for sulphafurazole. Calibration graphs were linear (r>0.9994, n=6), in the range 100-1000ngml-1 for the carboxylic acid metabolite of clopidogrel. The intra- and inter-day R.S.D. values were <3.1%, while the relative error Er was less than -9.6% (n=6). The limits of detection (3.3σ) and quantitation (10σ) for the carboxylic acid metabolite of clopidogrel were found to be 28 and 93ngml -1, respectively. The efficiency of the solid phase extraction procedure for the carboxylic acid metabolite of clopidogrel averaged 74.6%. © 2003 Elsevier Science B.V. All rights reserved

Development and validation of a high-performance liquid chromatographic method for the determination of buspirone in pharmaceutical preparations

A stability indicating, reversed-phase high-performance liquid chromatographic method was developed and validated for the determination of buspirone (Bsp) in pharmaceutical dosage forms. The use of a semi-micro XTerra MS C18 (150mm×3.0mm i.d., 5μm particle size) analytical column, results in substantial reduction in solvent consumption and increased sensitivity. The mobile phase consisted of a mixture of 0.010M ammonium acetate (pH 4.0) and methanol (55:45, v/v), pumped at a flow rate 0.30mlmin -1. The UV detector was operated at 245nm. The retention times for lidocaine (Ldc), which was used as internal standard, and buspirone were 4.57 and 7.72min, respectively. The calibration graph was ranged from 1.00 to 5.00μgml-1, while detection and quantitation limits were found to be 0.22 and 0.67μgml-1, respectively. The intra- and inter-day relative standard deviation (% R.S.D.) values were less than 1.94%, while the relative percentage error (% Er) was less than 4.0% (n=5). The method was applied to the quality control of commercial tablets and content uniformity test and proved to be suitable for rapid and reliable quality control. © 2003 Elsevier B.V. All rights reserved

A validated LC method for the determination of clopidogrel in pharmaceutical preparations

A stability indicating, reversed-phase high-performance liquid chromatographic method was developed and validated for the determination of clopidogrel in pharmaceutical dosage forms. The determination was performed on a semi-micro column, BDS C8 (250×2.1 mm i.d., 5 μm particle size); the mobile phase consisted of a mixture of 0.010 M sodium dihydrogen phosphate (pH 3.0) and acetonitrile (35:65, v/v), pumped at a flow rate 0.30 ml min-1. The UV detector was operated at 235 nm. The retention times for clopidogrel and naproxen, which was used as internal standard, were 3.08 and 6.28 min, respectively. Calibration graphs are linear (r better than 0.9991, n=6), in concentration range 1.00-3.00 μg ml-1 for clopidogrel. The intra- and inter-day RSD values were less than 1.96%, while the relative percentage error Er was less than 2.0% (n=5). Detection and quantitation limits were 0.12 and 0.39 μg ml-1, respectively. The method was applied in the quality control of commercial tablets and content uniformity test and proved to be suitable for rapid and reliable quality control. © 2002 Elsevier Science B.V. All rights reserved

Development and validation of a reversed-phase ion-pair high-performance liquid chromatographic method for the determination of risedronate in pharmaceutical preparations

A stability indicating, reversed-phase ion-pair high-performance liquid chromatographic method was developed and validated for the determination of risedronate in pharmaceutical dosage forms. The determination was performed on a BDS C18 analytical column (250 mm × 4.6 mm i.d., 5 μm particle size); the mobile phase consisted of 0.005 M tetrabutylammonium hydroxide and 0.005 M pyrophosphate sodium (pH 7.0) mixed with acetonitrile in a ratio (78:22, v/v) and pumped at a flow rate 1.00 mL min-1. The ultraviolet (UV) detector was operated at 262 nm. The retention times of magnesium ascorbyl phosphate, which was used as internal standard and risedronate were 4.94 and 5.95 min, respectively. The calibration graph was ranged from 2.50 to 20.00 μg mL-1, while detection and quantitation limits were found to be 0.48 and 1.61 μg mL-1, respectively. The intra- and inter-day percentage relative standard deviations, %R.S.D., were less than 5.9%, while the relative percentage error, %Er, was less than 0.4%. The method was applied to the quality control of commercial tablets and content uniformity test and proved to be suitable for rapid and reliable quality control. © 2006 Elsevier B.V. All rights reserved

Second-derivative spectrophotometric determination of naproxen in the presence of its metabolite in human plasma

A second-derivative spectrophotometric method for the determination of naproxen in the absence or presence of its 6-desmethyl metabolite in human plasma is described. The method consists of direct extraction of the non-ionized form of the drug with pure diethyl ether and determination of the naproxen by measuring the peak amplitude (mm) in the second-order derivative spectrum at a wavelength of 328.2 nm. The efficiency of the extraction procedure expressed by the absolute recovery was 94.6 ± 0.7% (mean ± s) for the concentration range tested, and the limit of quantification attained according to the IUPAC definitation was 2.42 mg l-1. The linear dynamic range for naproxen was 5.0-100.0 mg l-1, the correlation coefficient for the calibration graphs was excellent, r = 0.99993 (n = 6), the precision (S r) was better than 4.58% and the accuracy was satisfactory (E r < 2.32%). The results obtained by the proposed method were in good agreement with those found by an HPLC method

Simultaneous determination of clopamide-pindolol combination in tablets by zero-crossing derivative spectrophotometry

A first-derivative spectrophotometric method, using a 'zero-crossing' technique of measurement has been used for determining clopamide-pindolol mixture in tablets. In the first-derivative mode the zero-crossing points of clopamide and pindolol occur at 272.6 and 262.4 nm, respectively. The relative ease offered by this technique for the quantification of these drugs with closely overlapping bands was demonstrated. The linearity of the calibration curves was satisfactory (r = 0.9998) and the precision (RSD%) better than 1.89. Detection limits were 0.50 and 0.44 μg ml-1 for pindolol and clopamide, respectively. No spectral interferences from tablet excipients were found. Applications are given for the assay of commercial tablets and content uniformity test. The procedures proved to be suitable for rapid and reliable quality control. © 1994

A porous graphitized carbon column hplc method for the quantification of paracetamol, pseudoephedrine, and chlorpheniramine in a pharmaceutical formulation

A simple, rapid, and stability-indicating HPLC method has been developed, fully validated, and applied to the quantification of paracetamol, pseudoephedrine hydrochloride, and chlorpheniramine maleate in a pharmaceutical formulation, using hydrochlorothiazide as an internal standard. Chromatographic separation was achieved isocratically on an RP porous graphitized carbon analytical column (125 × 2.1 mm id, particle size 5 μm) using 5.0 mM ammonium acetate-acetonitrile (35 + 65, v/v) mobile phase at a flow rate of 0.50 mL/min. UV spectrophotometric detection at 220 nm was used. The method had linear calibration curves over the range of 30-70 mg/mL for paracetamol, 1.8-4.2 mg/mL for pseudoephedrine hydrochloride, and 120-280 ng/mL for chlorpheniramine maleate. The intraday and interday RSD values were less than 3.2% for all compounds, while the relative error was less than 2.9%. Accelerated stability studies performed under various stress conditions proved the selectivity of the method. The developed method was applied successfully to QC and content uniformity tests of commercial tablets

Determination of hyoscine N-butyl-bromide, lidocaine hydrochloride, and paracetamol in injection forms using solid-phase extraction, high-performance liquid chromatography, and UV-Vis spectrophotometry

A solid phase extraction procedure using strong cation exchange (SCX, benzenesulfonic acid) cartridges followed by a reversed-phase HPLC assay was applied to the analysis of hyoscine n-butylbromide and lidocaine hydrochloride in injection forms. The chromatographic separation was performed on a BDS C-18 column. The mobile phase consisted of a mixture of acetonitrile: ammonium acetate 0.2M, (30:70, v/v) pumped at a flow rate 1.2 mL/min. The UV detector was operated at 254 nm. A UV-Vis spectrophotometric method was also developed for the determination of paracetamol in the injection forms. The method consists of subsequent dilution of the injection forms and measure of the absorbance value at 242.7 nm. Relative standard deviation was less than 0.95% for HPLC and less than 0.78% for the spectrophotometric method. Detection limits were 1.05, 0.96 and 0.67 μg/mL for hyoscine n-butylbromide, lidocaine hydrochloride and paracetamol, respectively

Determination of clopamide-pindolol combination in tablets by fourth-order derivative UV spectrophotometry

A fourth-derivative spectrophotometric procedure for the simultaneous determination of clopamide and pindolol in binary mixtures, in tablets, is described. Calibration graphs are linear (r = 0.9999), the precision (RSD%) better than 2.22 and the percentage relative error (Er%) less than 0.12. No spectral interference from tablet excipients was found. Applications are given for the assay of commercial tablets and content uniformity test. The procedure proved to be suitable for rapid and reliable quality control. © 1993

Determination of captopril and captopril-hydrochlorothiazide combination in tablets by derivative UV spectrophotometry

Assay procedures based on derivative spectrophotometry have been developed for the determination of captopril alone or in combination with hydrochlorothiazide in tablets. Captopril (5.0-25.0 μg/ml) can be determined by measuring the amplitude of the maximum D2,258nm of the second-order derivative spectrum. Combinations of captopril (6.0-14.0 μg/ml) and hydrochlorothiazide (3.0-7.0 μg/ml) in a ratio of 2:1 can be determined using the simultaneous equations method with measurements of the amplitudes of the maximum-minimum of the first-order derivative spectrum D1,278-260nm and D1,213nm. The linearity of the calibration curves was excellent (r>0.9997), the precision (RSD) better than 1.6% and the relative errors (Er) less than 2.6%. The methods were succesfully applied to commercial tablets containing captopril alone or captopril in combination with hydrochlorothiazide. © 1992