New flow cell for electrochemical detector

What is it about?

A gap flow cell (gap-FC) as a capillary-end electrochemical (EC) detector, incorporating exchangeable screen-printed electrodes, that facilitates adjustment of the gap distance between the capillary outlet and working electrode down to 30 mm was investigated. The analytical performance of the gap-FC was assessed in terms of detector response (current), the efficiency of EC conversion of ferrocyanide, and effective cell volume, as a function of flow rate and gap distance, within a range of 0.1e200 mLmin
1 and 30e100 mm, respectively. As a result, an efficiency of EC conversion within the range of ~1.5e11% (~3e16 times higher than wall-jet FC), at an effective cell volume of ~30e75 nL, was achieved. The gap-FC was applied as a liquid chromatography EC detector, coupled with standard and capillary format liquid chromatographs, where the analytical performance of gap-FC was compared with that of a UV detector. With the standard LC, the sensitivity for ascorbic acid, 2,3-dihydroxybenzoic acid and pyrocatechol, was greater than with the UV detector, with limits of detection (LODs) one order of magnitude lower for the gap-FC (0.10 mM, 0.09 mM, 0.19 mM, respectively, RSD 1.35e3.8%, n ¼ 9, linearity r2 ~0.99 for concentration range 1e100 mM). LODs of test electroactive solutes using the gap-FC were ~2 times lower than LODs reported in existing literature using standard EC detectors, including wall-jet and thin-layer FCs.

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Why is it important?

Sensitive and selective detection is always an issue in flow through methods.

Perspectives