Continuum Source Atomic Fluorescence of Arsenic

Although continuum sources in atomic fluorescence spectrometry have been thought to be of little use for studies below 200 nm, a high pressure xenon arc continuum source has proved to be effective for exciting arsenic at 189.0, 193.7, and 197.2 nm. To enable good atomization characteristics and a constant signal for wavelength scans, a commercially prepared mixture of arsine in H2 was used as the sample. A wavelength scan is presented, comparisons of sensitivities at various wavelengths are shown, and some indication of the quenching characteristics of Ar and N2 are included in this work. Analytical studies show that the 189.0 nm line has the greatest sensitivity and when this line is used in conjunction with the 235.0 nm line, a dynamic range of approximately 700 is expected. The detection limit in terms of mass flow of As, is found to be about 0.5 ng/s at the 189.0 nm line.