Laser-Excited Atomic Fluorescence of Some Precious Metals in the Air/Acetylene Flame

A pulsed, tunable dye laser pumped with a nitrogen laser is used to excite the atomic fluorescence of Ru, Pd, Ir, Pt, and Au in an air/acetylene flame. The detection limits obtained have been improved about 40 to 400 times, excepting those for Au. These elements can be detected at the ng/mL (ppb) level or less with analytical curve linearity of over four orders of magnitude. Improvement of the detection limits was achieved mainly by the use of a large-aperture detection system and a frequency-doubled dye laser for excitation of nonresonance atomic fluorescence. Interferences among these five elements and also from Rh, Os, Co, Cu, and Ni were investigated. The detection limits obtained are superior to flame atomic absorption spectrometry and flame atomic emission spectrometry and comparable to or better than the best detection limits of atomic emission inductively coupled plasma spectrometry and dc plasma spectrometry. Of course, the spectral selectivity greatly exceeds other analytical atomic spectroscopic methods.