A reticulated vitreous carbon spectroelectrochemical detector for flow injection analysis and liquid chromatography

Abstract

A spectroelectrochemical detector for flow injection and liquid chromatography is described. The detector design has dimensions of a standard 1 cm sample cuvette with a replaceable reticulated vitreous carbon working electrode. No special cell holder or modifications to the spectrophotometer are required to use the detector. Chronocoulometry is used to indicate a trend from thin-layer behavior toward semi-infinite difhsion behavior as the electrode pore size increases. Ferro-/ferrkyanide solutions were used to evaluate the flow injection characteristics of the detector. A sampling rate of 180 injections per hour was used. Linear calibration curves in the micromolar range were achieved with a reproducibility of 2-7%. A mixture of phenol, chlorophenols, and nitrophenols was used to investigate the simultaneous electrochemical and optical response for liquid chromatography. KEY WORDS Spectroelectrochemistry, reticulated vitreous carbon, detector.

Easily Constructed Spectroelectrochemical Cell for Batch and Flow Injection Analyses

“…The SEC cell trait that most significantly affects detection limits is thus its sensitivity. For potential difference SEC measurements of the simple type described here and in the cited references, , the theoretical calibration sensitivity for batch assays may be estimated from Beer's law as and the flow sensitivity may likewise be estimated as where Δε is the difference in molar absorptivities for the analyte and its electrolysis product at the analytical wavelength. Detection limits for batch SEC determination of a given analyte are thus determined primarily by cell path length, while detection limits in flow mode depend additionally upon the cell's dispersion and conversion.…”

“…It is readily available and inexpensive, and its porosity and thickness may be selected to yield a suitable compromise between optical and electrochemical characteristics . Though numerous reports on the use of RVC electrodes in various flow electrolysis applications have been published, − only a few have entailed SEC measurements 8,9,11 and just one of these 9 involved use of the RVC as an OTE (the others employed downstream optical sampling).…”