Speciation of Chromium in Capsules by Capillary Electrophoresis–Inductively Coupled Plasma–Mass Spectrometry

Abstract

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 µm ID × 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 µg g⁻¹ of Cr(III) were detected in the capsules.

Keywords:

• Capillary electrophoresis
• Chromium speciation
• Gelatin capsules
• Inductively coupled plasma-mass spectrometry