Development of SdFFF-ETAAS for characterising soil and sediment colloids

Abstract

A technique involving the coupling of sedimentation field-flow fractionation (SdFFF) with electrothermal atomic absorption spectrometry (ETAAS) was developed for characterising soil and sediment colloids. The combined SdFFF-ETAAS technique has high resolution particle separation capability and relatively high sensitivity element analysis. The technique was used to determine the distributions of metals in two natural soil and sediment samples and a model iron oxide coated kaolin. The results obtained using ETAAS detection were compared with those obtained using inductively coupled plasma mass spectrometry (ICP-MS) and excellent agreement was obtained. SdFFF-ETAAS is a cheaper and more widely available technique than SdFFF-ICP-MS. For the dilute colloid suspensions analysed here, the direct ETAAS analysis yielded the same results as aqua regia extraction. Analysis of the soil and sediment samples before and after extraction with selected reagents enables the metal content in particle coatings to be assessed across the size distribution.