VALIDATED DETERMINATION OF TOTAL ARSENIC SPECIES OF TOXICOLOGICAL INTEREST (ARSENITE, ARSENATE AND THEIR METABOLITES) BY ATOMIC-ABSORPTION SPECTROMETRY AFTER SEPARATION FROM DIETARY ARSENIC BY LIQUID EXTRACTION - TOXICOLOGICAL APPLICATIONS

A validated method for the selective extraction of total As species of toxicological interest (arsenite, arsenate and mono- and dimethylated arsenic species) from urine, followed by atomic absorption spectromet ric determination, is described. The mechanisms involved in extraction were studied and the extraction method was optimized. The urine sampl e was acidified with concentrated HCl and KI and sodium hypophosphite were added. Under these conditions, As species were reduced to their c orresponding iodide arsines, extracted with toluene and back-extracted with 1 mmol l(-1) NaOH solution. Only inorganic arsenic and its metab olites in humans (monomethylarsonic and dimethylarsinic acid) mere ext racted. Arsenobetaine of dietary origin was not extracted. This method can detect if any As increase in urine originates from inorganic As i ntoxication or only from dietary non-toxic As species such as arsenobe taine.