Development of a Simple Method for the Determination of Toxicologically Relevant Species of Arsenic in Urine Using HG-AAS

Humans are exposed to arsenic (As) in the environment, in both organic and inorganic forms, and it has been widely demonstrated that the inorganic arsenic species (arsenate and arsenite) are the main toxic ones being drinking water one of the main sources of exposure worldwide. Urinary arsenic level is the recommended biomarker for assessing human exposure risks. Absorbed inorganic arsenic is metabolized to monoand dimethylated arsenic compounds (MMA and DMA) prior to its excretion in urine. In this work, a simple procedure for the determination of toxicologically relevant arsenic species in urine (sum of As(III), As(V), MMA and DMA) using Hydride Generation Atomic Absorption Spectrometry (HG-AAS) was developed in order to obtain a feasible and selfsustainable technology for analysis and epidemiological studies when other expensive techniques are not available. Sample preparation was based on the derivation of arsenic species with L-cysteine. The limit of detection was 1.5 μg L, linearity up to 50 μg L and analytical precision was 12 % (relative standard deviation, RSD %, n=10). Trueness was evaluated using spiked urine samples as well as a reference material. The range of acceptation for recoveries was established in 85-115% by means of a t-test at the 95% significance level. Recoveries for the four As species from spiked urine samples were in the range 87.8-113.5 %. The recovery from a reference material was 100.7%. The comparison between the HG-AAS and high performance liquid chromatography-hydride generationcoupled to inductively coupled plasma mass spectrometry (HPLC-HG-ICPMS), considered as a gold standard technique, showed good agreement (R = 0.94) for forty urine samples. The figures of merit were adequate for the determination of relevant species of As for biomonitoring purposes according to international regulations and it can be postulated as an alternative to more expensive techniques.