Abstract
Interfering and enhancing effects of various acids and metal salts matrices were studied for the flameless atomic absorption determination of total arsenic [As (III), As (V) and dimethyl arsinic acid (DMAA) ] in water samples. The limit of the ashing temperature for arsenicals was dependent on the nature of anions in the matrix. With changing anions, the limit temperature increased in the following order : chloride<nitrate<sulfate. Phosphate in the matrix seemed possible to form an easily atomizable compound with arsenic at nearly 1150°C, although serious interference was observed less than 1000°C as reported by the others. All arsenicals were vaporized together with alkali halides at high ashing temperature. The sensitivities for the determinations of arsenicals were almost same in the presence of the same cation. High sensitivities were observed in the presence of calcium, magnesium or nickel salts matrices and the sensitivity of DMAA was greatly improved. The presence of nitric acid (0.1 N) and calcium sulfate is recommended for the determination of total arsenic in water samples to obtain the same sensitivity.
