Continuum Source Atomic Fluorescence of Arsenic

Abstract

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.