Determination of hydrogen radicals in analytical flames using electron spin resonance spectroscopy applied to direct investigations of flame-based atomization units for hydride generation atomic absorption spectrometry

The atomization mechanism for the low-temperature name used in hydride gene ration AAS has been studied by means of electron spin resonance (ESR) spect roscopy. By employing a miniaturized oxygen/hydrogen name torch, especially constructed to nt in the center of the ESR cavity, it was possible to dire ctly monitor the production of hydrogen radicals in the name, as well as th eir consumption upon introduction of arsine into the name. In this way, usi ng arsenic as a model analyte, it could for the first time be shown in dire ct experiments that hydride-forming elements are atomized by radical recomb ination in the name. The spatial distribution of hydrogen radicals in the q uartz tube, whose dimensions are similar to those used for atomizing hydrid e-forming elements in AAS, was also studied. The principle of directly meas uring radicals in miniature flames should be applicable also to other impor tant analytical name processes, such as native and modified flame ionizatio n and flame photometric detectors for gas chromatography.