A stock solution of Sn 50mgL−1 was prepared by appropriate
dilution of a Fluka concentrated standard solution (1000mgL−1,
in HCl 1mol L−1), to guarantee the stability of the analyte. Standard
solutions of Sn were prepared daily from the stock solution
by suitable dilutions in a solution of CPB 1×10−3 mol L−1 and HCl
5×10−2 mol L−1. In the study of the influence of surfactants on the
fluorescence reaction solutions of cetyltrimethylammonium bromide
(CTAB) and sodium dodecylsulphate (SDS) were also tested.