Determination of monomethylarsonic acid and dimethylarsinic acid in urine by liquid chromatography-tandem mass spectrometry

J Anal Toxicol. 1999 Jul-Aug;23(4):257-61. doi: 10.1093/jat/23.4.257.


A method for the simultaneous measurement of monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in human urine using liquid chromatography-tandem mass spectrometry with electrospray ionization (LC-ES-MS-MS) was developed. The multiple reaction monitoring mode (MRM) was used for quantitation. The protonated molecule ions (m/z 141.0 for MMA and m/z 139.0 for DMA) were selected as precursor ions, and the same fragment ion AsO+ (m/z 91.1) was monitored as the product ion. A two-step liquid-liquid extraction of MMA and DMA from urine provided recoveries of 92-100%. The coefficients of variation were lower than 7% for the within-day precision and lower than 11% for the between-day precision. The limit of quantitation was 25 microg/L as As for the two analytes. The assay was linear over the range of 25-800 microg/L.

MeSH terms

  • Arsenicals / urine*
  • Cacodylic Acid / urine*
  • Chromatography, Liquid / methods
  • Chromatography, Liquid / standards
  • Herbicides / urine*
  • Humans
  • Mass Spectrometry / methods
  • Mass Spectrometry / standards
  • Sensitivity and Specificity


  • Arsenicals
  • Herbicides
  • Cacodylic Acid
  • monomethylarsonic acid