Batch-injection amperometric determination of pyruvic acid on an electrode modified by silver-palladium binary system

The catalytic activity of silver (Ag) and palladium (Pd) particles deposited on the surface of a screen printed electrodes (SPE) during the electrooxidation of pyruvic acid (PA) was established. On the anodic curves of PА oxidation on chemically modified electrodes (CME), one current maximum was observed, the height of which linearly depends on the substrate concentration. With sequential deposition of Ag and Pd particles on the SPE surface (Ag-Pd-SPE), an increase in the oxidation current of PA was recorded, exceeding the currents on the CME modified by individual metals. The Ag-Pd-SPE electrode was used as part of an amperometric detector to quantitative determination of PA under conditions of batch-injection amperometry (BIA). The flow method reduces the lower bound of the determined contents by two orders of magnitude compared to static conditions. In the batch injection system (BI-system), the linear concentration range, represented in bilogarithmic units, was observed in the range from 5 × 10-6 to 5 × 10-2 M. The developed method for determining PA was tested in the analysis of urine. Matrix components such as urea, creatinine, uric and lactic acids did not interfere with the results of the determination. The proposed method increases the sensitivity, selectivity, expressiveness and productivity of the analysis (450 determinations/hour).