ARGON SHIELDED, HIGHLY FUEL-RICH, HYDROGEN-OXYGEN DIFFUSION MICROFLAME - A NEW HYDRIDE ATOMIZER

摘要

A new hydride atomizer for atomic fluorescence (AFS) and possibly also for atomic absorption spectrometry (AAS) is described. Named flame-in-gas-shield atomizer, it is actually an argon-shielded highly fuel-rich hydrogen-oxygen diffusion microflame. Its sensitivity and blank noise the for AFS detection are compared with those of a miniature diffusion flame. Selenium hydride is employed as a model for other analytically important hydrides. The influence of gas flow rates on AFS and AAS signals at various observation heights is determined. Analyte free atoms are removed from the observation volume by chemical reactions with oxygen penetrating from ambient atmosphere. No significant quenching effect due to interaction of excited Se atomic levels with nitrogen or hydrogen was found. The AFS sensitivity of the flame-in-gas-shield atomizer is at least two times higher and its inherent noise is substantially lower than with the miniature diffusion flame. This offers the possibility to improve limits of detection in AFS more than by one order of magnitude. (C) 1997 Elsevier Science B.V. [References: 17]