Ion chromatography: Measurement of trace ions in high-concentration basic samples.

Measurement of trace anions using inline neutralization processing

The analytical methods for high-concentration sodium hydroxide (NaOH) are specified in JIS K1200 Industrial Sodium Hydroxide Parts 1 to 10. Among these, the methods for measuring chlorides include the mercuric thiocyanate spectrophotometric method, the modified Holthart method, and the ion chromatography analysis method. The mercuric thiocyanate spectrophotometric method is often avoided due to the strict handling and management of mercury compounds. The modified Holthart method quantifies chlorides by adding an excess of silver nitrate solution and performing back titration with ammonium thiocyanate solution, but it is not suitable for quantifying low-concentration chlorides in samples. The ion chromatography analysis method involves complex pretreatment operations and carries the risk of sample contamination; however, this application note introduces a method that automates the pretreatment step using cation exchange resin inline. This automated pretreatment is a technique for inline neutralization using our suppressor technology. It can accommodate not only NaOH but also many high-concentration basic samples, allowing for the analysis of anionic components in the samples.

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