Optimization of a new cloud point extraction procedure for the selective determination of trace amounts of total iron in some environmental samples

摘要

A new, simple, and rapid cloud point extraction (CPE) procedure system, combined with flame atomic absorption spectrometry (FAAS), was developed for selective separation, preconcentration, and determination of trace amounts of total iron in some environmental samples. The complexing agent, N,N'-(2,2'-(ethane-l,2-diylbis(oxy))bis(ethane-2,l-diyl))bis(2-chloroacetamide) (EDBOCA), is selective at pH 5.0 for only Fe(II) and Fe(III) ions in the presence of Cu(II), Pb(II), Cd(II), Mn(II), Co(II), Cr(III), Cr(VI), Ni(II), Zn(II), Al(III), Mo(VI), Pd(II), Pt(IV), Au(III), and V(V) ions. The procedure is based on the complexation of Fe(III) ions with EDBOCA reagent in the presence of Triton X-114 (TX-114) as a non-ionic surfactant. The optimum conditions for the CPE of Fe(III) ions were investigated with respect to several experimental parameters such as pH of the solution, TX-114 and EDBOCA concentrations, incubation time and temperature, and centrifugation rate and time. The detection limit for Fe(III) ions based on the 3 times the standard deviation of the blanks (N:10) was found to be 1.22 μg L~(-1), while the relative standard deviation (RSD) was 4.2%. Environment Canada TM-25.3 and CRM-SA-C Sandy Soil C, as certified reference materials, were used, and spike tests were applied to validate the method. The method was applied to some real environmental samples to evaluate their total iron levels.