An analytical method based on liquid-liquid extraction has been developed and validated for analysis of agomelatine in human plasma. Fluoxetine was used as an internal standard for agomelatine. A Betasil C18 (4.0 × 100 mm, 5 µm) column provided chromatographic separation of analytes followed by detection with mass spectrometry. The method involves simple isocratic chromatographic conditions and mass spectrometric detection in the positive ionization mode using an API-4000 system. The proposed method has been validated with linear range of 0.050-8.000 ng/ml for agomelatine. The intra-run and inter-run precision values are within 12.12% and 9.01%, respectively, for agomelatine at the lower limit of quantification level. The overall recovery for agomelatine and fluoxetine was 67.10% and 72.96%, respectively. This validated method was used successfully for analysis of plasma samples from a pharmacokinetic study.

A simple, precise and rapid isocratic reverse phase high performance liquid chromatographic method was developed for the simultaneous determination of paracetamol, chlorzoxazone and diclofenac sodium from tablet dosage form. The chromatographic separation was performed on an inertsil C18column (250 mm × 4.6 mm i.d 5 µm particle size). Mobile phase consisted of a mixture of phosphate buffer (0.02 M KH2PO4, pH adjusted to 3.7 using orthophosphoric acid), acetonitrile and methanol in the ratio of (25: 25: 50) at a flow rate of 1.0 mL/min. The wavelength was set at 220 nm. The proposed method was validated for linearity, accuracy, precision, LOD and LOQ. The calibration was linear over the range of 50-150 µg/mL for paracetamol, 50-150 µg/mL for chlorzoxazone and 5-15 µg/mL for diclofenac sodium. The retention times were found as 2.8 min for paracetamol, 4.2 min for chlorzoxazone and 6.4 min for diclofenac sodium. The method can be easily adopted for quality control analysis.

No abstract

An innovative high performance thin layer chromatography method was developed and validated for simultaneous determination of rofecoxib and tizanidine from tablet dosage form. Rosiglitazone maleate was used as an internal standard. The separation was achieved using HPTLC plates (Merck #5548) precoated with silica gel 60F254on aluminum sheets and a mobile phase comprising of toluene: ethyl acetate: methanol: triethyl amine in volume ratio of 6:3:0.5:0.1 (v/v/v/v), with chamber saturation of 15 min. The plate was developed up to 8 cm and air dried. The plate was then scanned and quantified at 235 nm. The linearity of rofecoxib and tizanidine were in the range of 3.75 µg/spot to 11.25 µg/spot and 0.30 µg/spot to 0.90 µg/spot respectively. The limit of detection for rofecoxib and tizanidine was found to be 45.00 ng/spot and 30.00 ng/spot respectively. The limit of quantification for rofecoxib and tizanidine was found to be 135.00 ng/spot and 90.00 ng/spot respectively. The percentage assay was found between the range of 99.58% to 103.21% for rofecoxib and 98.73% to 101.55% for tizanidine respectively, whereas recovery was found between 99.97% to 100.43% for rofecoxib and 100.00% to 101.00% for tizanidine by standard addition method. The proposed method is accurate, precise and rapid for the simultaneous determination of rofecoxib and tizanidine in dosage form

A simple and sensitive High-Performance Liquid Chromatography (HPLC) method with fluorescence detection for quantitation of telmisartan in rabbit plasma was developed and validated. Separation of telmisartan from plasma components was achieved on a Chromolith RP18e column (100 x 4.6 mm 5 µ). Losartan was used as an internal standard. A mobile phase consisting of 50 mM sodium phosphate buffer and acetonitrile in the volume ratio of 65:35 v/v was delivered at a flow rate of 3.5 mL/min.A simple and rapid sample preparation involved solid phase extraction using Varian Bond Elute C-18 cartridge. The linearity range of the proposed method was 4 to 375 ng/mL. The intra-day and inter-day coefficients of variation obtained for telmisartan were less than 4.90% and relative error was less than 9.08%. The overall recoveries for telmisartan and losartan were 101.7% and 100.0%, respectively. This validated method was used successfully for analysis of plasma samples from a pharmacokinetic study.