Characteristics of photometric and conductivity detection and their comparison in ion chromatography for anionic compounds

Abstract

The detection sensitivities of anionic compounds by conductivity detection (CD) and indirect photometric detection (IPD) were compared in non-suppressed ion chromatography. The reciprocal of peak area to noise ratio was used to compare the two detection methods for such common eluents as benzoate and phthalate at pH 4.3 and pH 6.7. The sensitivities of strong acid compounds were highest by CD at pH 4.3, while those of weak acid compounds were highest by IPD at pH 6.7. These results were consistent with theoretical equations for the two detection methods. The sensitivities of strong acid compounds by IPD exceeded those by CD with the phthalate eluent at pH 4.3, using eluent species such as 1, 5-naphthalenedisulfonate. Correlations between the two methods were excellent in the determination of inorganic anions in soluble fractions of monthly collected deposits.