Abstract: The study was performed to compare the effect of magnesium modifier (magnesium nitrate) with that of other modifiers (palladium nitrate and nickel nitrate) in determination of arsenic, antimony and selenium by atomic absorption spectroscopy with atomization in a graphite tube, with generation of hydrides and in situ pre-concentration in a graphite tube. The assumed criterion of a modifier performance was the magnitude of the analytical signal. It was found that in determinations with atomization in a graphite furnace the effects of all these modifiers were comparable, while in those with hydride generation and in situ pre-concentration in a graphite tube the magnesium modifier showed poorer performance (25% decrease of the analytical signal). In determinations of arsenic and selenium the analytical signal obtained with magnesium salt as a modifier was comparable with those obtained in the presence of all other modifiers. (C) 2002 Elsevier Science B.V. All rights reserved.

Abstract: The paper presents a design and construction of a simple set for determination of antimony and other hydride forming elements working on the has is of the method of injection flaw analysis with hydrides generation. The construction of the set is based on a commercially available flow system and bistable injection valve. The effect of position position of the injection valve with respect to the peristaltic pump and the kind of measurements (the peak area or the peak height), was analyzed. The limits of determination were established as 2.1-0.06 ng mL-1 for different Volumes of the injection loops, 50-850 µL, and the precision was 10.0-0.8%, respectively. The lowest limits of determination were obtained for the valve mounted behind the peristaltic pump (at the pumping side of the pump) and for measurements of the peak height. When the Valve was mounted in front of the peristaltic pump, the lowest limit of determination was obtained for measurements of the area under the peak. Preliminary results illustrating the performance of the set were obtained, determining the level of antimony in samples of natural waters (river, lake and underground waters) in the range from 0.20 ng mL-1 to 0.70 ng ml-1.