Direct determination of lead in blood by laser-excited flame atomic-fluorescence spectrometry

Abstract

A simple method for the determination of lead in blood by atomic-fluorescence spectrometry is described in which the sample is diluted with Triton-X (1+10). The sample is then nebulised directly into an argon-separated air-acetylene flame burning on a circular, home-made, capillary burner. Aqueous standards can be used for calibration purposes. The direct line fluorescence of lead at 405.8 nm is measured after excitation at 283.3 nm provided by a frequency doubled pulsed tunable dye laser pumped by a XeCl excimer laser, thus avoiding any scattering due to the matrix. The laser peak power was approximately 40 kW at the UV wavelength and the fluorescence was highly saturated even when the beam size was expanded in the flame to ca. 15 mm diameter. By diluting 0.1 ml of blood to 1 ml and using discrete sampling in the flame, the detection limit was found to be 4 ng ml^–1 and can be decreased considerably by taking a larger volume of blood. Several blood samples, as well as quality control samples, were analysed and the results found to be in very close agreement with those provided by the well established Delves cup atomic-absorption, graphite furnace atomic-absorption and anodic-stripping voltammetry methods.