APPLICATION OF EXPERIMENTAL-DESIGNS IN OPTIMIZATION OF A HYDRIDE GENERATION QUARTZ FURNACE ATOMIC-ABSORPTION SPECTROMETRY METHOD FOR SELENIUM DETERMINATION

An optimization of the hydride generation quartz furnace atomic absorp tion spectrometry (HG-QFAAS) method used for selenium trace determinat ion was performed. Experimental designs-at two levels, including seven factors, were used, allowing the evaluation of the influence of each analytical variable on peak area, repeatability and signal-to-noise ra tio (S/N). For peak area, the most significant factors are the helium and oxygen flow-rates. The NaBH4 flow-rate and hydride generator tempe rature have a strong significant effect on repeatability. No factor is really essential for the S/N. The detection limit is 1.5 ng of Se-IV (3s(b)). The absorbance is found to be linear over the range 1.5-60 ng . A 3.72% relative standard deviation is obtained for six determinatio ns of 10 ng of Se-IV standard solution. A Community Bureau of Referenc e (BCR) certified reference material (CRM) 402 White Clover was studie d, in order to control the quality of the determination. The total sel enium contents were determined using the HG-QFAAS optimized method and then compared with the results given by an electrochemical method (di fferential pulse cathodic stripping voltammetry).