ARSENIC SPECIATION BY MICELLAR LIQUID-CHROMATOGRAPHY WITH INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRIC DETECTION

Four environmentally and biologically important arsenic species, dimet hylarsenic acid (DMA), monomethylarsonic acid (MMA), As(III) and As(V) are separated by micellar liquid chromatography. Linear dynamic range s for the four species are three orders of magnitude and detection lim its are in the picogram range with inductively coupled plasma mass spe ctrometric (ICP-MS) detection. This paper discusses in detail the deve lopment of the chromatographic conditions. The micellar mobile phase, which consisted of 0.05 M cetyltrimethylammonium bromide, 10% propanol and 0.02 M berate buffer, showed good compatibility with ICP-MS. This method allowed direct injection of urine samples onto the chromatogra phic system without extensive pretreatment and presented no interferen ce from chlorine in the matrix. Detection limits are comparable with o ther LC-ICP-MS studies. An SRM urine sample was used to demonstrate th e applicability of this technique to ''real-life'' situations. Results indicated that DMA, MMA and As(V) were present in the urine sample.