Studies on The Periodecety of Mole Sensitivity and Atomization in Flameless Atomic Absorption Spectrometry

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In flameless atomic absorption spectrometry the tungsten tube and metal-coated tubes were used and the periodic trends of sensitivity and atomization mechanism were studied comparing with those for the graphite tubes. Furthermore, the method the tungsten-coated tube was applied to the determination of tin in biological and environmental samples.1. Of matrix modifiers used so far the oxide of tungsten has been shown to enhance the tin sensitivity and the tungsten-coated tube was prepared by soaking for at least 24 hr in sodium tungstate solution (5 % w/v). In this work, the tungstate-coated tube was prepared without soaking in the tungstate solution. The coating process involved just injecting 100 mu 1 of a sodium tungstate solution (0.01 MU) into a graphite tube, followed by heating the tube according to the temperature program similar to an atomization cycle. The coated-surface gave stable signal for at least 100 firings. The sensitivity for tin, tantalum and silicon was improved with … More the tungstate-coated tubes compared with that obtained with uncoated tubes.2. Although for tin in the simple matrix 0.01 MU HCl the tungstate-coated pyrolytic graphite (W-PG) tube gave the highest sensitivity, for tin in the complex matrix of fish fillet the tungstate-coated nonpyrolytic graphite (W-NPG) tube gave the highest and most stable absorption signal. The W-NPG tube gave the good analytical result for tin analysis in sea bass : 2.40 <plus-minus> 0.09 mu g/g (5 determinations) compared with the reported value 2.4 <plus-minus> 0.1 mu3. The use of the W-coated tube and palladium (II) solution as a matrix modifier provided the direct method of the tin determination in sea water without pretreatment : a 1 % absorption was refered to 0.0028 ng at an ashing temperature of 1700 ﾟC.4. Organosilicon as well as inorganic silicon were determined with a high sensitivity by using the W-coated tube. It was found that the atomization process is SiO_<2(g)> -> SiO_<2(g)> -> SiO_<(g)> -> Si_<(g)> for both the samples. Less