DETERMINATION OF CYANIDE ION AND CYANOGEN CHLORIDE BY USING PHOTOMETRIC DETECTION WITH 4-PYRIDINECARBOXYLIC ACID-PYRAZOLONE IN ION-EXCLUSION CHROMATOGRAPHY

4-Pyridinecarboxylic acid(PCA)-pyrazolone was used for the determination of cyanide ion and cyanogen chloride as a reagent in the postcolumn derivatization method. The cyanide ion and cyanogen chloride were separated by ion-exclusion chromatography (IEC). The cyanide ion was then converted into cyanogen chloride by a reaction with Chloramine T. The cyanogen chloride derived from the cyanide ion, as well as that present in the sample solution, were treated with a PCA-pyrazolone solution and detected at 638 nm. The reaction parameters were optimized for cyanide ion and cyanogen chloride as follows: reaction coil for the conversion of cyanide ion into cyanogen chloride, 2 m X 0.5 mm i.d.; reaction coil for reaction with PCA-pyrazolone reagent, 10 m X 0.5 mm i.d.; concentration of Chloramine T, 0.1% in 0.02 mol dm-3 phosphate buffer (pH 7.4); concentration of PCA-pyrazolone reagent, 0.2 mol dm-3 PCA and 0.03 mol dm-3 pyrazolone; flow rate of the reagent, 0.5 cm3 min-1 each; reaction temperature, 100-degrees-C. The chromatographic conditions were as follows: column, IEC column (300 mm X 8 mm i.d.) packed with hydrogen form sulfonated polystyrene gel (ion exchange capacity: 3.5 meq/g.dry); mobile phase, 1 X 10(-3) mol dm-3 sulfuric acid; flow rate, 1.5 cm3 min-1; detection wavelength, 638 nm. The detection limits (S/N = 3) for the cyanide ion and cyanogen chloride were 2.5 X 10(-4) and 2.9 X 10(-4) mg dm-3 as cyanide ion. The linear range was over 3 orders of magnitude, from 0.001 to 1 mg dm-3. The relative standard deviation was 3.8% (n = 10) for 0.001 mg dm-3 cyanide ion solution.