Far-ultraviolet excited laser-enhanced ionization spectrometry of As, Se, Cu, and Sb in air/acetylene and Ar/O-2/acetylene flames

Laser-enhanced ionization (LEI) measurements of As, Se, Sb, and Cu in air/a cetylene and Ar/O-2/acetylene flames are reported. The use of far-UV excita tion wavelengths to perform one- and two-step LEI excitation from the groun d states of As, Se, and Sb is reported for the first time. Significant ioni zation background signals are observed for far-UV excitations in the air/ac etylene flame, but are reduced by substituting an (80:20) Ar/O-2 mixture fo r air as the flame oxidant. The sensitivities of the individual LEI techniq ues are also increased by the Ar/O-2 gas substitution. The limits of detect ion for As, Se, Sb, and Cu are 30, 0.5, 9 and 2 ng/mL, respectively, and co mpare favorably with previous LEI reports. Due to the poor atomization char acteristics of As and Se, the utility of hydride generation (HG) sample int roduction with LEI detection has been explored. Although high sensitivity h as been observed for the HG-LEI approach, limits of detection were not eval uated due to nonlinear responses of the signals with respect to analyte con centration.