Brief summary of methodologies

This technique developed by Small et al. in 1975 [1] is usually employed for the separation and determination of mixtures of inorganic anions in water. However, applications have also been found for the determination of many organic anions in water. 

At the heart of the ion chromatography system is an analytical column containing an ion exchange resin on which various anions (and/or cations) are separated before being detected and quantified by various detection techniques, such as spectrophotometry, atomic absorption spectrometry (metals) or conductivity (anions). 

Ion chromatography is not restricted to the separate analysis of only anions or cations, and, with the proper selection of the eluent and separator columns, the technique can be used for the simultaneous analysis of both anions and cations. 

The original method for the analysis of mixtures of anions used two columns attached in series packed with ion exchange resins to separate the ions of interest and suppress the conductance of the eluent, leaving only the species of interest as the major conducting species in the solution. Once the ions were separated and the eluent suppressed, the solution entered a conductivity cell, where the species of interest were detected. 

The analytical column is used in conjunction with two other columns, a guard column which protects the analytical column from troublesome contaminants, and a preconcentration column. The intended function of the preconcentration column is twofold. First, it concentrates the ions present in the sample, enabling very low levels of contaminants to be detected. Second, it retains non complexed ions on the resin, while allowing complexed species to pass through. 

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As noted previously, this brief summary of methodologies is based primarily on two recent reviews (NRC 1993 Smith and McNeill 1995). Since the first of those reviews was completed, the utility of several of the experimen-... 

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