Simultaneous Determination of Rofecoxib and Tizanidine by HPTLC

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 60F 254 on 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

Simultaneous Determination of Paracetamol, Chlorzoxazone and Diclofenac Sodium in Tablet Dosage Form by High Performance Liquid Chromatography

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 C18 column (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