Enhancement of the Capabilities of Inductively Coupled Plasma Mass Spectrometry Using Monosegmented Flow Analysis

Flow injection (FI) in combination with inductively coupled plasma mass spectrometry (ICPMS) is advantageous for the analysis of volume-limited samples and is invaluable for the analysis of corrosive samples that would prematurely degrade ICPMS components. However, the dispersion process with 50-mu L injections in FI degrades ICPMS sensitivity. Monosegmented flow analysis (MSFA), where the sample plug is in the middle of 1 mL of air, eliminates dispersion while preserving the rinsing effect of the carrier. More reproducible as well as sharper, narrower, and more symmetrical peaks result with MSFA than FI, leading to a 2-fold improvement in detection limit and a 5-fold increase in sample throughput versus FI. Furthermore, by facilitating the formation of small droplets during nebulization, the air surrounding the sample even enhances sensitivity by 20-40%, depending on the element, compared to that obtained with direct sample aspiration. Coupling MSFA to ICPMS, which does not degrade analytical performance, is advantageous for the determination of Pt in 0.50 M H2SO4 electrolyte from a simulated fuel cell. It also enables the multielement analysis of a 150-mu L buffer sample containing as little as 60 mu g of plant protein, thus further extending the range of applications of ICPMS.