Determination of tellurium and lead at picogram levels by candoluminescence spectrometry

Abstract

Tellurium and lead are determined by candoluminescence using the coated-rod technique. Tellurium is found to give its maximum luminescence from magnesium oxide coated on calcium oxide-calcium sulphate rods with an emission peak at 470 nm. Perchloric acid is used as a coactivator. A number of parameters were studied and optimised and a linear calibration graph was obtained for the range 0–12 ng using 2 µl of sample. The detection limit was 25 pg µl^–1 with a relative standard deviation of 7.0%. Lead gave a stronger luminescence in a calcium fluoride matrix compared with a calcium oxide-calcium sulphate matrix. Hydrochloric acid was used as coactivator. A linear calibration graph was obtained in the range 0–100 ng using a 1-µl sample volume. The detection limit was 6 pg µl^–1 with a relative standard deviation of 5.0%. A number of interfering elements were studied for their effect on both elements.