Thermal stabilisation 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 sodium fluoride as a chemical modifier has been studied. The study includes atomisation from dual-cavity platforms and analysis by scanning electron microscopy, energy dispersive X-ray spectrometry and X-ray photoelectron 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 around 1350 degrees C are reached. The effect of the modifier on the sensitivity of measurements of different phosphorus compounds was also studied. A possible explanation:of the comparatively low sensitivity of phosphorus measurements with this particular modifier, approximately 38% less as compared with palladium, is given.