CHARACTERIZATION OF INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY WITH SEGMENTED-FLOW INJECTION

The figures of merit for inductively coupled plasma mass spectrometry with flow injection were determined for a range of elements (Al, V, Cr, Mn, Fe, Co, Ni, Cu, As, Se, Mo, Cd, Sb and Pb) using three different carriers, water, air, and air-segmented water, for which injections were made within air segments. Compared with flow injection into water, narrower and symmetrical peaks were observed with either the air or air-water carrier. The last two carriers provided twice the sample throughput obtained with water, and more reproducible injections. Peak height sensitivities were enhanced by a factor of 2-5 using the air or air-water carriers, but part of this enhancement was due to increased solution transport efficiency when air was present in the carrier. When water as carrier was replaced by air-water, detection limits improved by a factor of 2-6 for V, Cr, Mn, Fe, Ni, Cu, As, Se, and Cd, remained about the same for Al, Co, Sb, and Pb, and were degraded by a factor of 2 only for Mo. The water and air-water carriers showed similar memory effects, reduced in comparison with the air carrier. Overall, flow injection into the air-water carrier resulted in the best precision, sensitivity, and detection limits for the greatest number of elements.