Multiple microflame quartz tube atomizer - further development towards the ideal hydride atomizer for atomic absorption spectrometry

摘要

The development of an improved type of hydride atomizer for atomic absorption spectrometry - multiple microflame quartz tube atomizer (MMQTA) - is presented. The main feature of this atomizer is recurrent analyte atomization proceeding over its whole optical tube length, which is achieved by production of H-radicals at multiple points within the tube by oxygen microflames burning in the hydrogen-containing atmosphere. The MMQTA design optimization leading to a complete filling of the observation volume with H-radicals is described. The influence of individual atomization parameters is discussed Optimum H-radical producing oxygen intake into the MMQTA was found to correspond to a H_2:O_2 stoichiometric (3:1) ratio. The performance of the individual MMQTA tube designs is evaluated and compared to a typical externally heated quartz tube atomizer (0EHQTA) - the liearity of calibration graphs for As, Se and Sb is significantly improved in all MMQTA tubes, without compromising the sensitivity, simplicity, low cost and easy operation. In fact, the free atom reactions within the tube causing calibration curvature are avoided up to an analyte concentration of at least 200 ng ml~(-1) for Se and Sb and 100 ng ml~(-1) for As. Tolerance limits of 0.7, 1.4, 0.2 #mu#g ml~(-1) are achieved for the atomization interferences of As on Se, Se on As, Sb on Se and Se on Sb, respectively, which is an improvement by 1-2 orders of magnitude in comparison to the conventional EHQTA with the same hydride generation system.