Challenges in Plasma Spectrometry for the Analysis of Limited, Expensive, and Toxic Materials: From Aerosol Generation, Diagnostics, to Practical Applications Open Access
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This research is centered on fundamental studies to improve the analytical performance of plasma based spectrometries with an emphasis on the development of liquid sample introduction devices suitable for the analysis of limited, expensive, and toxic materials. The use and improvement of a demountable-direct injection high efficiency nebulizer (d-DIHEN) is investigated as a suitable interface for high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) to detect toxic arsenic species at nano-liter solution flow rates (0.9 µL min-1) and sample volume (50 nL). Separation of five arsenic species is achieved in less than 12 minutes providing absolute detection limits comparable to previously reported data at higher solution uptake rates (20 µL min-1 to 1 mL min-1) and larger sample injection volumes (20 µL to 100 µL).To increase the potential for the d-DIHEN to be used as a universal direct injection micronebulizer, an automated sample introduction system is successfully incorporated for the first time. The measurement of the phosphorus content in acid-digested nucleotides and deoxyribonucleic acid (DNA) is performed with an ICP optical emission spectrometer (ICP-OES). The solution uptake rate and volume are reduced from 170 µL min-1 to 30 µL min-1 and 10 mL to 2.4 mL, respectively, thereby drastically reducing the required DNA sample mass. The use of direct injection also improves P (I) 213.617 nm sensitivity by a factor of 4 on average. This successful approach will aide in the development and certification of nucleic acid reference materials, particularly for samples that are typically limited in volume.The measurement of key aerosol parameters is essential for the development of an efficient low-flow nebulizer. An aerosol diagnostic technique developed in our laboratory, combines Interferometric Droplet Imaging (IDI) with particle tracking velocimetry (PTV) to provide spatial mapping of surviving droplets in an ICP while simultaneously determining droplet size, velocity, and evaporation rate. To overcome the fundamental limitation of pneumatic nebulization a heated (90 °C) laminar flow interface has been designed to assist in the development of an argon electrospray sample introduction system for low-flow applications using inductively coupled plasma spectrometry.