Fundamental aspects and applications of liquid sample introduction techniques in inductively coupled plasmas.

摘要

The objectives of this research centers on two distinct, but complementary areas of plasma spectroscopy. The primary focus is the development, characterization, and application of novel sample introduction devices for inductively coupled plasma atomic emission spectrometry (ICPAES) and mass spectrometry (ICPMS), including the investigation of a unique dual-spray chamber, a replaceable capillary concentric nebulizer and a large-bore direct injection high efficiency nebulizer (LB-DIHEN). These studies offer a better understanding of aerosol generation and transport processes for micronebulization and facilitate the direct introduction of samples that are expensive, hazardous or of limited volume for ICP spectrometries. Because low sample consumption efficient devices are of vital importance for speciation studies, a portion of this research is focused on developing useful interfaces using the DIHEN to couple microbore high performance liquid chromatography and capillary electrophoresis with ICP spectrometric detection. The utility of cited approaches is examined in the speciation and quantitation of organomercury and alkyl-lead compounds; the separation of vitamin B12 (cyanocobalamin) from potentially harmful cobamides and cobinamides analogues; and in the electrophoretic separation of eight lanthanides. In all studies, fundamental properties of aerosol and the plasma are connected to analytical measurements. The investigation of physical properties of plasma discharges includes the determination of electron number densities in several discharges and extensive theoretical calculations of Stark-broadened lines derived from the Model Microfield Method.;The result of this research provides several key findings in relation to sample introduction system and practical applications including: (1) aerosol transport processes are similar in a cyclonic and a dual-type spray chamber despite difference in geometries, providing comparable analytical figures of merits; (2) practical and easily assembled nebulizers with replaceable solution capillaries are easily implemented, providing a low-cost alternative to conventional concentric nebulizers without compromising performance; (3) capillary blockage with direct injection devices can be alleviated using a LB-DIHEN, demonstrated in the analysis of chromium in human lung fibroblast cells; and (4) direct injection devices provide higher separation efficiency in speciation techniques due to the reduction in dead volume, demonstrated using microbore high-performance liquid chromatography and capillary electrophoresis with ICPMS detection.