Determination of arsenic compounds using inductively coupled plasma mass spectrometry with ion chromatography

Abstract

A combined system of inductively coupled plasma mass spectrometry (ICP-MS) with ion chromatography (IC) has been used for the determination of arsenic compounds. Arsenous acid (As III), monomethylarsonic acid (MMAs), dimethylarsinic acid (DMAs), trimethylarsine oxide (TMAsO) and arsenobetaine were separated by anion-exchange chromatography. Subsequently eluates were directly introduced into ICP-MS and detected at m/z 75. Separation parameters were optimized for the arsenic compounds as follows: column, two Excelpak ICS-A35 columns (150 mm × 4.6 mm I.D. each) packed with polymer-based hydrophilic anion-exchange resin (ion-exchange capacity: 0.15 mequiv. /g dry); mobile phase, 10 · 10 −3 M tartaric acid; flow-rate, 1.0 ml/min; column temperature, 50°C; injection volume, 20 μl. The detection limits for the five arsenic compounds were from 0.22 to 0.44 μ/l as an As element. The repeatability was better than 5% (relative standard deviation) for all arsenic compounds. The IC-ICP-MS system was applied to the determination of arsenic compounds in the urine of DMAs-exposed rats. As III, MMAs, DMAs and TMAsO were detected in the urine.