Suppressed ion chromatographic analysis of anions in environmental waters containing high salt concentrations

The literature on the application of suppressed ion chromatography for the analysis of low concentrations of anions in the presence of a high concentration of matrix ions is critically reviewed. It is reported in the literature that suppressed ion chromatographic determinations of anions such as sulfate, arsenate, oxalate, etc., give erroneous results when low concentrations are quantified in the presence of high salt concentrations. In many cases this is believed to arise from overloading of the column by matrix ions, typically by matrix anions. However, as discussed in this review, the erroneous results in the suppressed ion chromatographic determination of small concentrations of anions such as sulfate, oxalate and molybdate in matrices having very high salt concentrations are not caused by column overloading but are due to some anion-proton interactions within the suppressor. Determination of anions of strong acids such as Cl^-, Br^-, and I^- is not affected and they can be accurately quantified by suppressed ion chromatography in aqueous matrices containing high salt concentrations. Suppressed ion chromatography as a tool for the accurate analysis of small concentrations of anions in the presence of high ionic strength matrices, such as subsurface waters, well waters, and aqueous extracts of sandy soils has also been reported.