A spectrophotometric detection procedure for the high-performance ion chromatographic determination of alkali and alkaline earth metal and ammonium cations, after chemical suppression of the eluent, is proposed. Measurements at 200 nm revealed the presence of hydroxide ions, which bear a stoichiometric relationship with the eluted M(n+) cations. The detection limits and sensitivities were similar to those obtained by the usual conductivity method. The suggested procedure, when tested in the analysis of samples of ammonium cations, gave responses dependent also on the pH of the suppressed solution and relative pK(a) values. Fitting of the calibration graphs by means of a non-linear regression routine also allows the determination of the equilibrium constants of the cations.
UV Spectrophotometric Detection in the Ion Chromatographic Analysis of Alkali and Alkaline-Earth Metal and Ammonium Cations
PASTORE, PAOLO;
1992
Abstract
A spectrophotometric detection procedure for the high-performance ion chromatographic determination of alkali and alkaline earth metal and ammonium cations, after chemical suppression of the eluent, is proposed. Measurements at 200 nm revealed the presence of hydroxide ions, which bear a stoichiometric relationship with the eluted M(n+) cations. The detection limits and sensitivities were similar to those obtained by the usual conductivity method. The suggested procedure, when tested in the analysis of samples of ammonium cations, gave responses dependent also on the pH of the suppressed solution and relative pK(a) values. Fitting of the calibration graphs by means of a non-linear regression routine also allows the determination of the equilibrium constants of the cations.Pubblicazioni consigliate
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