The effect of two kinds of eluents on the speciation of Al, Mn, and Fe by size-exclusion chromatography of some Brazilian soil solutions

Abstract

Size-exclusion chromatography is a powerful tool for distinguishing dissolved organic matter in relation to its molecular size. However, problems may arise in the choice of the most appropriate eluent composition, regarding the gel used. In the present work, soil solution samples from four Brazilian topsoils were analyzed by high-performance liquid chromatography (HPLC) using a size-exclusion polymer-based column (Superdex 75 HR 10/30, Pharmacia). Water and 0.01 mol L-1 NaCl were investigated as mobile phases. The analysis of the UV peak distribution as well as their corresponding Fe, Mn, and Al concentrations suggested that the salt solution should be preferred since it minimizes unwanted interactions between the sample and the support material. Fe, Mn, and Al speciation calculated by the Geochem-PC program involving the Mattigod and Sposito Mixed Model was compared with the Fe, Mn, and Al-organic complex concentrations determined by SEC-HPLC/GFAAS. No correlation was found for Mn and Fe. For Al a significant non-linear correlation was observed. © 2005 2005 Taylor and Francis Group LLC.