SIMULTANEOUS DETERMINATION OF METHYLPARABEN, PROPYLPARABEN AND THIMEROSAL BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AND ELECTROCHEMICAL DETECTION

A reversed-phase high-performance liquid chromatographic method using amperometric detection has been developed for the analysis of methylpa raben, propylparaben and thimerosal. The liquid chromatographic separa tion of the three preservatives was made possible on a C-18-bonded sil ica column with a mixed solvent consisting of methanol and aqueous 0.0 2 M phosphoric acid (59:41, v/v). A potential value of + 1.25 V versus Ag/AgCl was chosen for simultaneous analysis. The limits of detection were 1, 2 and 5 ng for a 20 mu l injection volume of methylparaben, p ropylparaben and thimerosal, respectively. The analysis time of less t han 20 min in this study was found to be applicable for routine analys is of these compounds in pharmaceutical products. (C) 1997 Elsevier Sc ience B.V.