Lab-on-valve (LOV) system coupled to irreversible biamperometric detection for the on-line monitoring of catechol

The analytical performance of lab-on-valve (LOV) system using irreversible biamperometry for the determination of catechol was evaluated. By integrating miniaturized electrochemical flow cell (EFC) designed and processed which is furnished with two identical polarized platinum electrodes, into the LOV unit, the lab-on-valve system combines sampling with analysis, realizing automated on-line analysis for catechol in a closed system. The biamperometric detection system was established to record the relationship between oxidation current and time by coupling the irreversible oxidation of catechol at one pretreated platinum electrode with the irreversible reduction of platinum oxide at the other pretreated platinum electrode. Factors influencing the analytical performance were optimized, including the potential difference (ΔE), buffer solution and pH, and flow variables in the LOV. A linear calibration curve was obtained within the range of 1.0 × 10−6-5.0 × 10−4 mol L−1 of catechol with the detection limit (3σ) of 5.09 × 10−7 mol L−1. The relative standard deviation (R.S.D.) was 2.39% for 11 successive determinations of 1 × 10−5 mol L−1 catechol and the sample throughput was 35 h−1. Moreover, this proposed method was applied to the analysis of catechol in beer sample, which was testified by high-performance liquid chromatography (HPLC).