Inexpensive Green Method for Diclofenac Assay Utilizing Sequential Injection Chromatography

Sequential injection chromatography (SIC) is a recent inexpensive miniaturized separation technique. The current manuscript reported the development of a new SIC method for the assay of diclofenac in pharmaceutical formulations. Chemometrics was exploited for the first time to optimize SIC methodology. The 2(3) full-factorial design was adopted to screen the effect of mobile phase composition, sample volume, and flow rate on retention time and peak height. The optimum chromatographic conditions were: C-18 monolithic column (25 x 4.6 mm); mobile phase composition methanol:water (50:50, v/v), sample volume 60 mu L, flow rate 40 mu L s(-1). The detection was carried out using a miniaturized fiber optic spectrometer set at 284 nm. Satisfactorily, separation was achieved in 0.92 min with the number of theoretical plates of > 180,000 and peak symmetry 1.21. The method enjoyed good precision with relative standard deviation values for intra- and inter-day precision of 1.47 and 2.15%, respectively. The use of large sample volume rendered the method sensitive with the limits of detection and quantification of 0.32 and 1.07 mu g mL(-1), respectively. The remarkable advantages of the method are high rapidity (sample frequency 23 sample h(-1)) and reagent saving (total consumed volume 3.0 mL) and thus better safety for the environment.