The effects of the supporting electrolyte on the simultaneous determination of vitamin B2, vitamin B6, and vitamin C using a modification-free screen-printed carbon electrode†
To provide new choices and to replace the complicated steps of synthesizing modified electrodes, this research reports the systematic investigation of the effects of different supporting electrolytes on the electrochemical behavior of vitamin B2 (VB2), vitamin B6 (VB6), and vitamin C (VC) using a common screen-printed carbon electrode (SPCE) to achieve simultaneous detection. The roles of various well-known supporting electrolytes, including Britton–Robinson buffer solution (BRBS), acetate buffer solution (ABS), and phosphate buffer solution (PBS), in the electrochemical oxidation of VB2, VB6, and VC were carefully evaluated by square wave voltammetry (SWV). From a successive investigation based on the ionic conductivity of the species contained in the supporting electrolytes, PBS at pH 3.5 was selected as a suitable supporting electrolyte for the simultaneous detection of VB2, VB6, and VC. Under the optimized conditions, the simultaneous detection of VB2, VB6, and VC provided satisfactory sensitivity, selectivity, and reproducibility even when using a common electrode. To demonstrate the practicality and reliability of the proposed analytical procedure, the simultaneous detection of VB2, VB6, and VC was performed in mixed vegetable and fruit juice samples and urine samples by SWV, and the results were compared with those obtained by chromatographic detection. Therefore, this method was found to be simple and may be a new alternative for the simultaneous determination of VB2, VB6, and VC in practical applications.