A low-pressure graphite furnace atomic absorption spectrometry technique Is presented which, for aqueous Pb samples at 0.15 Torr, results In a 2 orders of magnitude reduction In sensitivity and a working range that extends to about 1 pg. The limit of detection Is 5 ng of Pb. Sticking Is diminished for refractory analytes (e.g., V), thus reducing memory effects and peak tailing. Solid sample analysis Is demonstrated for Pb In a phosphorlzed Cu alloy, for which low-pressure atomization minimizes Cu vaporization while allowing for quantitative determination of Pb when compared to a calibration curve prepared from aqueous standards. In addition, the appearance of multiple peaks suggests the use of the technique for differentiating between various forms or locations of Pb within the sample. This Is In contrast to atmospheric vaporization where only one broad peak Is observed.
Temperature programmed static secondary ion mass spectrometry is used to investigate surface chemical reactions of phosphate chemical modifiers used for the determination of Cd and Ag in electrothermal atomic absorption spectrometry. Cadmium-xyphosphorus reactions are initiated on the surface at dry cycle temperatures, with further stabilizing reactions occurring on the surface in the char cycle temperature range. This leads to a delay in the atomization of Cd to a higher appearance temperature. However, for the determination of Ag, addition of phosphate results in an attenuation in the atomic absorption spectrometric signal intensity with no change in appearance temperature. Similar Ag-xyphosphorus surface reactions are not observed.
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