Analysis of Conditioned Waters

In addition to high-purity water analysis, ion chromatography is the primary method used for analyzing conditioned waters, which is a lot more difficult, because the concentrations of the chemicals used for conditioning exceed the analyte concentrations by many orders of magnitude. 

A characteristic example for trace analysis of sodium in water containing ammonia on lonPac CS15 is illustrated in Fig. 9-50. Sodium concentrations around 1 pg/L can only be detected when injecting a large volume of 1000 pL The high resolution between sodium and ammonium on this stationary phase allows sodium quantification even in the presence of a 10,000-fold excess of ammonium. 

For the conditioning of feed water, ammonia is often used in combination with morpholine morpholine acts as corrosion inhibitor and ammonia is used for adjusting pH (Fig. 9-53). Both compounds can be separated from common inorganic cations on an lonPac CS14 weak acid cation exchanger. The tailing of the morpholine peak is reduced by adding 5 % (v/v) acetonitrile to the mobile phase. 

AutoNeutralization [107] is a suitable sample preparation technique for samples of this kind. The term AutoNeutralization describes an automated neutralization of acidic or basic samples with a special membrane suppressor to analyze traces of anions in strongly basic samples and traces of cations in strongly acidic samples, respectively. In the present case, the cations of the sample are replaced by hydronium ions, the sample being neutralized in that way. The schematic setup of an AutoNeutralization unit - coupled to an ion chromatograph - is depicted in Fig 9-245 in Section 9-11. The positive effects 

Analyte Spiked amount [pg/L] Measured amount [pg/L] Recovery rate [%] 

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