You are here:
SEPARATION OF TOXICOLOGICALLY RELEVANT ARSENICALS IN URINE USING A NEW SOLID PHASE EXTRACTION TECHNIQUE
Citation:
ADAIR, B., V. DEVESA I PEREZ, M. STYBLO, AND D. J. THOMAS. SEPARATION OF TOXICOLOGICALLY RELEVANT ARSENICALS IN URINE USING A NEW SOLID PHASE EXTRACTION TECHNIQUE. Presented at 45th Annual Society of Toxicology Meeting 2006, San Diego, CA, March 05 - 09, 2006.
Description:
Abstract - Metabolism and toxicity of arsenicals are critically influenced by the oxidation state of As. In human urine, inorganic and methylated arsenicals contain both As(III) and As(V). Because As(III) is easily oxidized, a method is needed to preserve the native oxidation state of arsenicals in urine. One approach is to quickly separate arsenicals based on As oxidation state, thus rendering subsequent oxidation immaterial to analysis. To do this, we optimized a solid phase extraction (SPE) method using thionalide-charged silica gel (Th-Si) that retains inorganic As (iAs), methyl As (MAs), and dimethyl As (DMAs) metabolites containing As(III) but does not retain these arsenicals containing As(V). In the optimized method, urine buffered to pH 8.5 (0.2 M phosphate) is applied to a Th-Si column and arsenicals containing As(V) are collected in the effluent. Analyses of arsenicals in urine and column effluents were performed by pH selective hydride generation-atomic absorption spectrophotometry. Method efficiency was examined in four validation trials using triplicate spiked urine reference materials (SRM 2670A low and Seronorm background) with 25 ppb, 100 ppb, or 1000 ppb total As (sum of iAs, MAs, DMAs). Few detectable As(III)-containing species in effluents proved high binding efficiency. Recoveries of As(V) species in effluents compared to spiked urine concentration were >93% except for 1000ppb DMA(V) at 87%; standard deviations (SD) were <16% for each spike concentration and arsenical. Concentrations in spiked effluent samples stored for one week were 7.4 + 7% (mean + std, n=12) lower than the original AsV species. Recoveries of iAsV, MMAV, and DMAV in naturally incorporated urine samples were 97 + 28, 118 + 25, and 103 + 16 (Mean + std, n= 3. The Th-Si method permits rapid and nearly quantitative separation of urinary arsenicals on the basis of As oxidation state and should be adaptable to field collections. (This abstract does not reflect US EPA policy.)