Arsenic speciation by micellar liquid chromatography with inductively coupled plasma mass spectrometric detection

Four environmentally and biologically important arsenic species, dimethylarsenic acid (DMA), monomethylarsonic acid (MMA), As(III) and As(V) are separated by micellar liquid chromatography. Linear dynamic ranges for the four species are three orders of magnitude and detection limits are in the picogram range with inductively coupled plasma mass spectrometric (ICP-MS) detection. This paper discussed in detail the development of the chromatographic conditions. The micellar mobile phase, which consisted of 0.05 M cetyltrimethylammonium bromide, 10% propanol and 0.02 M borate buffer, showed good compatibility with ICP-MS. This method allowed direct injection of urine samples onto the chromatographic system without extensive pretreatment and presented no interference from chlorine in the matrix. Detection limits are comparable with other LC-ICP-MS studies. An SRM urine sample was used to demonstrate the applicability of this technique to "real-life" situations. Results indicated that DMA, MMA and As(V) were present in the urine sample.