SIMULTANEOUS DETERMINATION OF ANTIMONY, ARSENIC AND SELENIUM IN NATURAL-WATERS BY MEANS OF HYDRIDE GENERATION COUPLED TO PLASMA SOURCE-MASS SPECTROMETRY

The hydride generation batch technique was used to determine simultaneously antimony, arsenic and selenium in natural waters. The volatilized hydrides, formed by adding sodium tetrahydroborate to the acidified sample, were purged out of the sample and transported directly to the plasma by means of the nebulizer gas flow. In this method, ammonium pyrrolidin-1-yldithioformate (APDC) replaced iodide as the reducing agent for antimony because iodide interferes in the hydride generation of selenium. The detection limits for a 10 ml sample, defined as three times the standard deviation of the blank, were 1.5 ng l-1 for arsenic, 2.4 ng l-1 for antimony and 6.3 ng l-1 for selenium. The precision for each element was better than 6%. The linear ranges of the method were checked for arsenic, antimony and selenium up to 2 mug l-1, but for arsenic and antimony these were significantly higher, with the carryover between the samples being the limiting factor at high concentrations. The total analysis time for a single sample was 10 min.