Determination of glutathione in pharmaceuticals and cosmetics by HPLC with UV and fluorescence detection

A selective HPLC determination of reduced glutathione (GSH) in pharmaceutical and cosmetic formulations is described based on prechromatographic derivatization with 4-(6-methylnaphthalen-2-yl)-4-oxo-2-buteneoic acid. The derivatization reaction is rapid under mild reaction conditions (10 min at ambient temperature and pH 7.5) and the excess reagent can be removed by liquid-liquid extraction. The thiol adducts were chromatographed on a C-8 column using 0.05 M triethylammonium phosphate (pH 4.0) — acetonitrile 68∶32 (v/v), as the mobile phase; UV and fluorescence detection (lem 450 nm, lexc 300 nm) were both used. The structure of the thiol adducts was confirmed by1H and13C NMR spectra using sodium methanethiolate as thiol nucleophile.