High-throughput elemental analysis of small aqueous samples by emission spectrometry with a compact, atmospheric-pressure solution-cathode glow discharge.

A miniaturized version of an atmospheric-pressure glow discharge using a solution as the cathode was recently evaluated for elemental analysis of continuously sampled aqueous solutions. Although continuous sampling is useful, transient analysis is required for certain applications, including chromatographic or similar separations, small-volume sampling, high-throughput sampling, and on-line preconcentration. The miniaturized solution-cathode glow discharge seems particularly well suited to transient analysis by virtue of its low dead volume and high sensitivity. Two benefits of transient analysis were exploited here: high throughput and small sample volume. Sampling 25-microL volumes at 1000 samples/h, the discharge achieved detection limits ranging from 5 pg (0.2 ppb) for Li to 6 ng (270 ppb) for Hg.