A speciation methodology to study the contributions of humic-like and fulvic-like acids to the mobilization of metals from compost using size exclusion chromatography-ultraviolet absorption-inductively coupled plasma mass spectrometry and deconvolution analysis.

High performance size-exclusion chromatography (HP-SEC) with UV absorption for organic matter detection and inductively coupled plasma mass spectrometry (ICP-MS) for elemental detection have been used to study the mobilization of metals from compost as a function of pH and the molecular mass of their complexes with dissolved organic matter (DOM). Due to its heterogeneous nature, organic matter mobilized from compost shows a continuous distribution of molecular masses in the range studied (up to 80kDa). In order to differentiate between the contribution of humic and fulvic acids (FA) to the organic matter mobilized in the pH range 5-10, their UV absorption chromatographic profiles have been deconvoluted with respect to the adjusted gaussian profiles of the humic and fulvic acids isolated from compost.

Mobilization and speciation of chromium in compost: a methodological approach.

An integral approach to study the mobility of chromium in compost is presented. The approach is based on batch pH dependence leaching tests and the analysis of the leachates for total chromium, chromium(VI) and complexes of chromium(III) with natural organic matter. As leachings are performed with no aggressive reagents (ultrapure water with added nitric acid or potassium hydroxide), the method can be considered a good approach to simulate natural scenarios.