Determination of inorganic anions in water samples by ion-exchange chromatography with chemiluminescence detection based on the neutralization reaction of nitric acid and potassium hydroxide

A faint chemiluminescence (CL) from the neutralization reaction of nitric acid and potassium hydroxide was enhanced by addition of iron(III) to the acid. The enhanced CL emission was suppressed by adding inorganic anions such as chloride, bromide, nitrite, nitrate and sulfate to the base. Based on the findings, a new post-column CL detection method was developed for the determination of the anions. Several kinds of anions were separated by anion-exchange chromatography using a potassium hydroxide solution as eluent. The effluent from the anion-exchange column was mixed with nitric acid containing iron(III) ions, and the CL was suppressed by the eluting anions. For each anion, linear calibration ranges extending from 100 ng ml(-1) to 100 mu ml(-1) were obtained. The relative standard deviations for five replicate measurements of 10 mu g ml(-1) were 1.3-4.3%. The present method was successfully applied to determine inorganic anions in water samples.