Selective reduction of arsenic species by hydride generation atomic absorption spectrometry. part 2 - Sample storage and arsenic determination in natural waters

Total arsenic, arsenite, arsinate and dimethylarsinic acid (DMA) were selec tively determined in natural waters by hydride generation - atomic absorpti on spectrometry, using sodium tetrahydroborate( III) as reductant but in di fferent reduction media. River water samples from the north region of Paran a State, Brazil, were analysed and showed arsenate as the principal arsenic al form. Detection limits found for As( III) (citrate buffer), As( III) + D MA (acetic acid) and As( III) + As( V) (hydrochloric acid) were 0.6, 1.1 an d 0.5 mg As L-1, respectively. Sample storage on the proper reaction media revealed to be a useful way to preserve the water sample.