STUDIES IN ATOMIC-FLUORESCENCE SPECTROSCOPY .7. FLUORESCENCE AND ANALYTICAL CHARACTERISTICS OF ARSENIC WITH A MICROWAVE EXCITED ELECTRODELESS DISCHARGE TUBE AS SOURCE

The construction of an electrodeless arsenic discharge tube and its use for atomic-fluorescence studies is described. Cool nitrogen-hydrogen and argon-hydrogen diffusion flames as well as normal premixed flames are considered as atom reservoirs and the atomic-fluorescence emission at 15 different wavelengths is evaluated. The diffusion flames give the largest emission signals at arsenic concentrations below 200 ppm, but show a premature curvature at higher concentrations because of the presence of an abnormally high density of arsenic atoms. Above 200 ppm of arsenic, the premixed air-acetylene flame is superior. The limit of detection at 1890 Å is 0.2 ppm of arsenic in the nitrogen-hydrogen diffusion flame and 1.0 ppm in the airacetylene flame. A long path-length diffusion flame is also particularly useful in atomic-absorption measurements because it absorbs very little radiation in the far ultraviolet region and gives an abundance of arsenic atoms. © 1968.