DEVELOPMENT OF A SIMPLE METHOD FOR SCREENING TOXICOLOGICALLY RELEVANT ARSENIC (AS) SPECIES IN WATER AND URINE BY HG-AAS FOR ROUTINE ANALYSIS IN URUGUAY

Recently, environmental and occupational exposure to As is being controlled in Uruguay. Total As in drinking water supplied for general population is being periodically assessed, and exposed workers biomonitoring is mandatory. Consequently, there is a need to develop analytical tools to evaluate levels of total As and its toxicologically relevant species in drinking water and urine.

The ICP-MS technique is not yet available in Uruguay for routine determinations, so the aim was to develop and optimize simple and fast analytical methods to determine total As and iAs species in water and to determine iAs as well as its methylated metabolites (MMA and DMA) in urine as a biomarker, to differentiate from dietary As (As-Bet) by HG-AAS detection, for routine applications.

After optimization of sample treatment (digestion with K₂S₂O₈/H₂SO₄ and reduction with KI/HCl), analytical determinations were performed using a commercial system for flow hydride generation (Varian VGA77/Varian 55B) and flame atomic absorption spectrometry detection. Recovery (90-115%) was evaluated by spiking samples with As(III) and As (V).The detection limit obtained was 0.3 μgL^-1, the precision is <5% expressed as RSD. The quantification limit was 1.0 μgL^-1.

The obtained results are adequate to drinking water limits of WHO < 10 μgL-1 and to urine, considering the international recommendations and Uruguayan regulations: As-Urine < 35 μgL-1 for occupational exposed workers (ACGIH-BEI®) and 10-20 μgL-1 for general population according (ATSDR, As Tox-Profile).

Analytical methods are being also optimized for the separation of urinary species, using high performance liquid chromatography, coupled with flow atomic hydride generation and atomic absorption spectrophotometry (HPLC –HG- AAS)

In sum, simple methodologies for routine monitoring of toxicologically relevant species of As in drinking water (iAs, As(III), As(V)) and in urine (iAs+DMA+MMA) were optimized using hydride generation flame atomic absorption spectrometry (HG-AAS) and are suitable for environmental epidemiological studies, biomonitoring, and risk assessment in Uruguay.