A new method for the analysis of arsenic species in urine by using HPLC-ICP-MS

Urinary arsenic speciation is considered to be an effective procedure to differentiate between toxic inorganic and less toxic organic arsenic exposure. The aim of the present work was to develop a new method for the simultaneous determination of the main arsenic species so far detected in urine: arsenite (As(III)), arsenate (As(V)), methylarsonic acid (MA), dimethylarsinic acid (DMA), and arsenobetaine (AsB). The method is based on anion exchange HPLC coupled on-line to an inductively coupled plasma mass spectrometer (ICP-MS) for element specific detection. Experimental parameters, such as column type and composition of the mobile phases were optimized in order to get best separation, little matrix interferences, lowest detection limits, and short total times of analyses. Best chromatographic conditions were obtained by using a Dionex AS14 anion exchange column and a gradient elution with tetramethylammonium hydroxide and ammonium carbonate as eluting compounds. The detection limits (3 sigma) were found to be in the sub mu g L-1 range. The method was applied to analyze different urine samples from persons with and without consumption of seafood. To avoid significant matrix influences, samples (24 h urine) had to be diluted 1 :5 with water and were filtered through a 0.45 mu m filter prior to analyses. Special attention was focused on the validation of the method according to the regulations of the "Deutsche Forschungsgemeinschaft" (DFG) for the analyses of hazardous substances in biological materials.