Evaluation of linear photodiode array detection for continuum source atomic absorption spectrometry with electrothermal atomization

Abstract

A 256 pixel linear photodiode array (LPDA) detector was fitted to a Spectrametrics echelle spectrometer for measurements by continuum source atomic absorption spectrometry with electrothermal atomization (ET-CSAAS). By selection of appropriate pixel regions, intensity values could be obtained for calculation of absorbance signals integrated over wavelength as well as time. Detection lmits obtained sequentially for Cd, Cr, Cu, Mn, Mo and Pb, with the LPDA, were similar in magnitude (4–24 pg) to those obtained with mechanical wavelength modulation and detection by a photomultiplier tube, using the same atomizer and spectrometer system. The calibration graphs obtained with the LPDA, however, were more useful analytically, as integration of the absorbance signals across the line profile increased the linear range. Four National Bureau of Standards (NBS)[now National Institute of Standards and Technology (NIST)] Standard Reference Materials, (SRMs) 1577a Bovine Liver, 1575 Pine Needles, 1572 Citrus Leaves and 1566 Oyster Tissue were analysed by ET-CSAAS with LPDA detection. The concentrations obtained for Cd, Cr, Cu, Mn, Mo and Pb were generally in good agreement with the certified values.