Comparison of pre-reducing agents for antimony determination by hydride generation atomic fluorescence spectrometry

A systematic study of antimony reduction prior to its determination by hydride generation atomic fluorescence spectrometry (HGAFS) was carried out. The efficiency of Image-cysteine, potassium iodide and potassium iodide/ascorbic acid was studied for this purpose. The hydride generation step was optimised in the presence of those pre-reductors. From the results, Image-cysteine was found to be the most suitable pre-reducing agent. Methodology was validated, obtaining detection limits lower than 90 ng l^-1 and repeatability and reproducibility better than 3% R.S.D. and 5% R.S.D., respectively, in all cases. In order to evaluate the methodology developed and the influence of the matrix, recovery from waters from different sources was tested by HG-AFS and also by inductively coupled plasma mass spectrometry (ICP-MS). Accuracy was assessed by analysing three water reference materials at different antimony concentration levels. The high sensitivity of the developed methodology enables it to be applied for monitoring drinking waters according to the maximum admissible concentration of antimony established by the EU Directives.