DETERMINATION OF TELLURIUM AND ANTIMONY IN NICKEL-ALLOYS BY LASER-EXCITED ATOMIC FLUORESCENCE SPECTROMETRY IN A GRAPHITE-FURNACE

Analytical laser excited atomic fluorescence of the metalloids tellurium and antimony in an electrothermal atomizer was studied. The detection limits Were 20 fg and 10 fg for tellurium and antimony respectively, equivalent to about 0.01 ng g-1 in nickel based alloys by direct solid sample analysis, for a 1 mg solid sample, or 1 ng g-1 by the dissolution method, for a 100 mg solid sample in 100 ml solution. The detection limits were three orders of magnitude better than those obtained by graphite furnace atomic absorption spectrometry. They were also comparable to, or better than, those by inductively coupled plasma mass spectrometry. The linear dynamic ranges of the calibration curves were found to be six and seven orders of magnitude for antimony and tellurium respectively. By use of aqueous calibration, tellurium was accurately determined in NIST nickel alloy Standard Reference Materials by both a solid sample method, with a relative standard deviation (RSD) of about 13%, and a dissolution method with an RSD of about 9%. Antimony in Pratt and Whitney ''A'' series nickel alloy standards was successfully determined by the dissolution method, with an RSD of about 7%, but by solid sampling the antimony method gave incomplete recovery. Molecular fluorescence backgrounds from nitric oxide and silicon monoxide were observed and discussed.