Design and Performance of a Time Multiplex Multiple Slit Multielement Flameless Atomic Absorption Spectrometer

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Abstract
The design and performance characteristics of a new multielement flameless atomic absorption spectrometer are presented. Radiation from four hollow cathode lamps is combined by beam splitters and directed through a Varian model 63 carbon rod atomizer and then into a special monochromator with a separate exit slit for each element. The light exiting from all slits is directed to a single photomultiplier tube. Absorbance signals from different elements are distinguished with a time multiplex approach. Data acquisition and presentation is accomplished with a PDP-11 computer system. The absolute light levels are lower than those normally encountered with single element atomic absorption resulting in signal shot noise limited measurements. Detection limits (in ppb) of 0.2 (Cd), 2 (Mn), and 8 (Pb) were determined under multielement conditions. The measurement precision of moderate absorbance multielement solutions was determined to be 7% with manual injection of 5 μl samples.