Direct analysis of silica by means of solid sampling graphite furnace atomic absorption spectrometry

This paper reports on the use of solid sampling-graphite furnace atomic absorption spectrometry for the direct analysis of synthetic amorphous silica. In particular, determination of hazardous elements such As, Cd, Cr, Cu, Pb and Sb is investigated, as required by regulations of the food industry.The conclusion of the work is that, after proper optimization of the working conditions, paying particular attention to the atomization temperature and the use of proper modifiers (graphite powder, HNO3 or Pd), it is possible to develop suitable procedures that rely on the use of aqueous standard solutions to construct the calibration curves for all the elements investigated. The proposed method shows important benefits for the cost-effective analysis of such difficult samples in routine labs, permitting fast screening of those elements that are very rarely present in this type of sample, but also accurate quantification of those often found, while offering low limits of detection (always below 0.1 mg g− 1) that comply well with legal requirements, and precision levels that are fit for the purpose (approx. 6–9% R.S.D.).

► Solid sampling GFAAS is investigated for the direct analysis of silica samples;
► a fast and simple methodology with aqueous standards for calibration is proposed;
► this method permits accurate determination of As, Cd, Cr, Cu, Pb and Sb in the samples of interest;
► LODs below 100 ng g− 1 and precision values in the 6–10% RSD range are achieved.