LC SEPARATION AND INDIRECT DETECTION OF ANALYTE ANIONS USING RU(PHEN)(3)(C1O(4))(2) AS A MOBILE-PHASE ADDITIVE - WAVELENGTH SELECTION AND APPLICATION

The application of the intense ultraviolet π - π * transition absorption band at 261 nm for indirect detection of analyte anions using Ru(phen3CIO42 as a mobile phase additive is studied. The results are compared with those obtained using the conventional absorption band at 447 nm for the d-π* charge transfer transition. Variation of the concentration of Ru(phen3CIO42 is shown to influence the sensitivity of the methods with absorption at the two wavelengths. Use of a low Ru complex concentration is found to reduce noise and increase the gain in absorbance per mole RuL32+ liberated, resulting in an increase in the signal-to-noise ratio. Using 0.01 mM Ru(phen3CIO42 and 261 nm as the absorption wavelength, the detection limits of the method as measured by 2 times the noise level for F−, CI−, Br−, and NO3− are 5 ppb (0.1 ng), 5 ppb (0.1 ng), 10 ppb (0.2 ng), and 10 ppb (0.2 ng), respectively. © 1994, Oxford University Press. All rights reserved.