Simple and multi-configurational flow-cell detector for UV–vis spectroelectrochemical measurements in commercial instruments

•A spectroelectrochemical flow detector is designed for analytical purposes.•Detector has standard dimensions for use on UV–vis spectrophotometers.•Detector can be configured to use optically transparent working electrodes.•Analytical performance of detector is tested with ferrocyanide/ferricyanide couple.

An original, simple and sensitive flow-detector for quantitative determination by electrochemical, UV–vis absorption or spectro-electrochemical techniques has been developed. It allows variable configurations for use in a number of analytical situations besides the possibility to use different types of electrodes and materials. The dimensions and format of the detector are suitable for fitting in a standard cell holder for macro cuvettes in commercial UV–vis spectrometers. The sensor has been verified as an optical detector measuring absorbance at 420 nm, due to ferricyanide, with a linear relationship for molar concentrations of between 10−5 and 10−3, with dispersions in the measurements of less than 1%. As an electrochemical detector, two different working electrodes, one made with a stainless steel (SS) pipe and another based on an indium tin oxide (ITO) layer, have been tested by measuring the current due to the oxidation of ferrocyanide while a constant potential is applied. The best results were obtained using the ITO layer because the SS electrode produces distorted chromatographic signals. Lastly, it was tested as a spectro-electrochemical sensor for both electrodes following absorbance at 420 nm of the ferricyanide electro-generated in the detector from the oxidation of injected ferrocyanide. Here, the best results were obtained using the SS electrode with a linear behaviour ranging from 1.2 × 10−4 M to 5 × 10−3 M and dispersions of 5.4% in terms of % RSD.

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