RESUMO
Two multichannel image detectors, a vidicon and a silicon photodiode array, were investigated for their performance as detectors in ultraviolet-visible absorption spectroelectrochemical experiments. Their spectral band-pass, dispersion, dynamic range, and precision of absorbance measurements were compared. o-Tolidine was used as a model compound to study their performance in a spectro-potentiostatic experiment using an optically transparent thin-layer electrode. Both detectors performed well, but the silicon photodiode array had twice the spectral resolution and dynamic absorbance range of the vidicon detector.
RESUMO
The Organic Electrochemistry Group at the National Bureau of Standards is pursuing several avenues of research of potential application to problems of clinical chemists. With one development, electrochemical detectors for liquid chromatography, organomercury species can be determined in biological tissues and other matrices. Spectroelectrochemistry is being used to characterize the redox behavior of metal complexes of bleomycin, an antitumor drug. Chemically modified electrodes are being developed as selective electrocatalytic sensors for organohalogen compounds and may lead to new sensors for clinically important analytes. Surface-enhanced Raman spectroscopy is helping characterize the polymer films used to modify the electrode surfaces. Another sensor is being developed for the detection of carboxylic acids: after the photocatalytic oxidation of the acids at a semiconductor electrode, the carbon dioxide produced is subsequently determined with a flow-through gas-sensing electrode. Finally, mathematical modeling may provide a better understanding of the fundamental processes involved in several of the above techniques.
