Development of a solid-phase extraction and derivatization method for polar carboxylic acids from aqueous extracts of inorganic multi-component incineration residues

A rapid and reliable GC/MS (EI and CI) method was developed for the identification of short-chain mono- and dicarboxylic acids in complex and strongly alkaline residues of municipal waste incineration. Such residues contain organic carboxylic acids in the mg/kg to μg/kg range, which may contribute to the mobilization of heavy metals. However, the alkalinity and the high salt loads of the matrix were found to be a serious problem in the analysis of short chain acids. Extraction with water, solid phase extraction, and derivatization were studied under these conditions. Solid-phase extraction with polymeric sorbents and derivatization with diazomethane can be combined in a reproducible manner to yield a robust and simple method which can be applied for screening unknown solids due to its wide applicability and the well identifiable methyl esters. Absolute recovery rates varied between 20 and 85% depending on the individual acids. Received: 13 November 1997 / Revised: 17 February 1998 / Accepted: 18 February 1998