Validation of the inorganic selenium speciation by the HG-QFAAS method using experimental designs
Résumé
An optimization of the hydride generation quartz furnace atomic absorption spectrometry (HG-QFAAS) method used for selenium speciation was performed for inorganic Se determination. Experimental designs at two levels, including five factors, were used. They allowed the evaluation of the influence of each analytical variable on peak area, repeatability and signal-to-noise ratio (S/N). The absolute and relative detection limits obtained are respectively 0.7 ng and 0.014 ng.mL-1 of Se(VI) (3σ). The absorbance is linear over the range 0.7-45 ng. A 5.45% relative standard deviation is obtained for six determinations of 10 ng of Se(VI) calibrant solution. The analysis of four aqueous samples - synthetic and natural - was carried out in order to validate the optimization. The Se(IV), Se(VI) and total inorganic selenium contents determined by the HG-QFAAS method were compared with values given by electrothermal atomic absorption spectrometry and differential pulse cathodic stripping voltammetry.