Second Derivative Synchronous Fluorescence Spectroscopy for the Simultaneous Determination of Chlorzoxazone and Ibuprofen in Pharmaceutical Preparations and Biological Fluids

A rapid, simple and highly sensitive second derivative synchronous fluorometric method has been developed for the simultaneous analysis of binary mixture of chlorzoxazone (CLZ) and ibuprofen (IP). The method is based upon measurement of the synchronous fluorescence intensity of these drugs at Δλ=60 nm in methanol. 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 0.2-4 μg/mL and 0.1-1.6 μg/mL for CLZ and IP, respectively with lower detection limits (LOD) of 0.028 and 8.3 × 10-3 μg/mL and quantification limits (LOQ) of 0.086 and 0.03 μg/mL for CLZ and IP, respectively. The proposed method was successfully applied for the determination of the two compounds in synthetic mixtures and in commercial capsules. The high sensitivity attained by the proposed method allowed the determination of both drugs and real human plasma samples. The mean % recoveries in real human plasma (n=3) were 87.69 ± 6.15 and 92.57 ± 4.39 for each of CLZ and IP respectively.