THERMAL STABILIZATION OF PHOSPHORUS DURING ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY USING SODIUM-FLUORIDE AS CHEMICAL MODIFIER

The stabilisation mechanism of phosphorus during its determination by electrothermal atomic absorption spectrometry in the presence of sodiu m fluoride as a chemical modifier has been studied. The study includes atomisation from dual-cavity platforms and analysis by scanning elect ron microscopy, energy dispersive X-ray spectrometry and X-ray photoel ectron spectrometry of the material accumulated onto totally pyrolytic graphite platforms. The results obtained from this study point toward a stabilisation mechanism which is of a physical nature, whereby the analyte is retained in the matrix of the modifier until temperatures a round 1350 degrees C are reached. The effect of the modifier on the se nsitivity of measurements of different phosphorus compounds was also s tudied. A possible explanation:of the comparatively low sensitivity of phosphorus measurements with this particular modifier, approximately 38% less as compared with palladium, is given.