New flow-through coulometric detector with renewable working electrode material for flow injection analysis and HPLC

• Renewable carbon-based coulometric detector for flow methods was constructed.
• Thymol and sulfamethizole determination methods were developed using this detector.
• Parameters of the methods prove the applicability of the detector.

Newly developed flow-through coulometric detector with renewable working material of glassy carbon microbeads was fabricated and its basic electrochemical parameters were studied by flow injection analysis using potassium ferrocyanide and hydroquinone as probes. Main advantage of the detector is its simple construction while maintaining good electrochemical parameters and high conversion degree. Practical application of the detector was proved by the development of new HPLC and FIA method of thymol and sulfamethizole determination in pharmaceutical preparations. Optimal determination conditions were found and calibration dependences were measured. A value of quantification limit 0.97 μmol L−1 for thymol and 0.040 μmol L−1 for sulfamethizole were obtained. Newly developed methods were used for determination of the studied compounds in pharmaceutical preparations. HPLC with spectrophotometric detection was used as a comparative method; results from both methods were in good agreement.