Application of hot platinum microelectrodes for determination of flavonoids in flow injection analysis and capillary electrophoresis

• The unheated and hot platinum microelectrodes were used for flavonoids detection.
• Cyclic voltammetry detection of flavonoids under FIA and CE condition was achieved.
• Increase of analytical signal in FIA and CE at hot Pt microelectrode is observed.
• Flavonoids were determined in natural plant and in pharmaceutical.
• The LOD are better than obtained under spectrophotometric or amperometric detection.

The determination of quercetin and rutin by flow injection analysis (FIA) and capillary electrophoresis (CE) using electrochemical detection was described. These flavonoids were determined at normal (unheated) and hot platinum microelectrodes using cyclic voltammetry. When quercetin or rutin is reaching the platinum electrode, a change of the current in the region of the platinum oxide formation is observed. Integration of the current changes in this in this region creates analytical signals in the form of peaks. An increase of temperature to about 76 ̊C in a small zone adjacent to the microelectrode causes an increase of the analytical signal by more than 6 times under FIA conditions. This method enables the use of hot microelectrodes as detectors in HPLC or CE. In CE the improvement of the analytical signal at hot microelectrodes is smaller than in FIA and increase only 1.3–3.4 times. Heated microelectrodes were used for analysis of the flavonoids in natural samples of the plant (extract of sea buckthorn) and a pharmaceutical preparation (Cerutin).

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