Accession Number : ADA188780

Title :   Electrosorptive Detection Based on Double-Layer Capacitance for Selective Anion Monitoring in Ion Chromatography. 1. Mercury Electrodes.

Descriptive Note : Technical rept. 1 Oct 86 - 30 Sep 87,

Corporate Author : PURDUE UNIV LAFAYETTE IN DEPT OF CHEMISTRY

Personal Author(s) : Ramstad, Tore ; Weaver, Michael J

PDF Url : ADA188780

Report Date : 25 Sep 1987

Pagination or Media Count : 41

Abstract : A novel scheme is presented for the detection of selected anions in ion chromatography based on changes in differential double-layer capacitance, Delta C sub d, for a metal electrode at a suitable electrode potential induced by specific anion adsorption. The detector in the liquid chromatography-double-layer capacitance (LC-DLC) arrangement described here is a hanging or dropping mercury electrode in a large-volume wall-jet configuration. The aqueous-phase anions observed to readily be detected using this approach include chloride, bromide, iodide, azide, thiocyanate, and thiosulfate. The Delta C sub d-analyte concentration relationship can be arranged to be approximately linear at least over the range 1-100 ppm. A welcome feature of the technique is its insensitivity to ionic concentration gradients in the flowing stream. Another virtue of LC-DLC is its selectively, although it is less sensitive for the detection of complexing anions in comparison with faradaic electrochemical detection (FEC) based on mercury oxidation. Dual detection schemes were also devised, involving DLC monitoring at two potentials or DLC combined with faradaic electrochemical detection.

Descriptors :   *ELECTROCHEMISTRY, *ELECTRODES, *ION DENSITY, *MERCURY, ADSORPTION, ANIONS, CAPACITANCE, CHLORIDES, CHROMATOGRAPHY, COMPLEX COMPOUNDS, DETECTION, FARADAY EFFECT, GRADIENTS, IONS, LAYERS, METALS, MONITORING, OXIDATION, THIOCYANATES

Subject Categories : Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE