Determination of chlorzoxazone, diclofenac potassium, and chlorzoxazone toxic degradation product by different chromatographic methods

Abstract

The presented study was intended to design two validated, simple, and precise chromatographic methods for the determination of chlorzoxazone (CHZ) and diclofenac potassium (DIC) in the presence of chlorzoxazone nephrotoxic degradation product, 2-amino-4-chlorophenol (ACP) which was reported to be its main impurity. Reversed-phase high-performance liquid chromatography (RP-HPLC) was the first method where chromatographic separation was performed on ZORBAX Eclipse Plus C8 column using methanol—water—phosphoric acid (75:25:0.05, by volume) as the mobile phase at a flow rate of 1 mLmin−1. CHZ, DIC, and ACP retention times were found to be 4.26, 7.94, and 3.17, respectively, using photodiode array detector (DAD) at 230 nm. The calibration curves showed good linear relationships in the concentration ranges of 3–45 μg mL−1 for CHZ, 3–40 μg mL−1 for DIC, and 5–45 μg mL−1 for ACP. The second method was thin-layer chromatography (TLC) at which chromatographic separation was carried out on Merck TLC silica gel 60 F2...