Determination of L-cysteine in amino acid mixture and human urine by flow-injection analysis with a biamperometric detector.

摘要: Abstract Based on the electrocatalytic oxidation of cysteine at pretreated platinum electrode and flow-injection biamperometry for irreversible couple, a novel electrochemical detector is proposed selective determination in amino acid mixtures human urine samples. A thin-layer flowthrough cell was used to achieve large surface area volume ratio. Two identical electrodes were mounted with an applied potential difference 10 mV. By coupling two independent processes, namely, reduction oxide, biamperometric detection scheme has been established. The resulting current linear over range 4 × −7 –4 −5 M limit 1 (15 pmol). selectivity tested by 55 foreign species including 26 ions, 11 acids, 6 vitamins, 12 other compounds possibly found urine. performs well as routine assay, showing high efficiency (180 samples/h) good reproductivity shown RSD 0.6% eight repeated determinations 2 −6 cysteine. samples are detected directly without need pretreatment or adding reagents.