SPECIATION OF CHROMIUM IN CAPSULES BY CAPILLARY ELECTROPHORESIS-INDUCTIVELY COUPLED PLASMA-MASS SPECTROMETRY

A novel method for the determination of Cr(III) and Cr(VI) in gelatin capsules is reported that involved separation by capillary electrophoresis and the determination using inductively coupled plasma mass spectrometry with a collision-reaction cell. The separation was achieved on a fused-silica capillary column (75 mu m ID x 30 cm length). The electrophoretic buffer was 20 mM NaH2PO4-5 mM Na2B4O7 (pH 6.0) with an applied voltage of 15 kV. Chromium species in the capsules were extracted into a buffer-5 mM 1,2-cyclohexanediaminetetraacetic acid mixture. The spike recoveries of chromium species were in the range of 87% to 95%. The detection limits of Cr(III) and Cr(VI) were 0.61 and 0.45 ng.mL(-1), and the procedure was applied for the speciation of capsules. Approximately 0.242-71.64 mu g g(-1) of Cr(III) were detected in the capsules.