Edwin Hernández, José Alvarado, Freddy Arenas and Mariano Vélez
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 °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.