Identification and quantification by LC-MS and LC-ICP MS of arsenic species in urine of rats chronically exposed to dimethylarsinic acid (DMAA)

Abstract

The potential of liquid chromatography-mass spectrometry (LC-MS) using electrospray ionization (ESI) was investigated for the identification and quantification of organoarsenic species excreted in rats urine chronically exposed to dimethylarsinic acid (DMAA). Quantification was performed by both LC-ESI-MS and LC-inductively coupled plasma mass spectrometry (ICP-MS). The detection limits of organoarsenic species in LC-ESI-MS with cation-exchange chromatography were 75–200 pg as arsenic. Although there are about ten times higher than that of LC-ICP-MS, LC-ESI-MS had a low enough detection limit to determine major metabolic arsenic species in the urine. LC-ESI-MS was applied to the identification of organoarsenic species in the urine. Major arsenic peaks in urine were identified as DMAA and trimethylarsine oxide using agreement of the spectra and retention times. Three unidentified arsenic peaks were found in the urine; one of these was determined to be tetramethylarsonium ion by agreement of both the spectrum and the retention time. LC-ESI-MS and LC-ICP-MS were also used to quantify organoarsenic in urine: good agreement between LC-ESI MS and LC-ICP-MS was obtained. Copyright © 1999 John Wiley & Sons, Ltd.