A microcavity hollow cathode discharge emission source has been designed and evaluated for ultratrace analysis of sub-μL samples of solution residues. It was found that sample drying time and cathode precondition had a significant effect on the signal-to-background and signal-to-noise ratios. Detection limits for Cu and Pb were determined to be 10 pg and 210 fg, respectively.
C. A. Morgan, C. L. Davis, B. W. Smith, and J. D. Winefordner, "Evaluation of a Microcavity Hollow Cathode Discharge Emission Source," Appl. Spectrosc. 48, 261-264 (1994)