Differential Pulse Voltammetric Determination of Selenocystine Using Selenium‐gold Film Modified Electrode

Abstract

Abstract Differential pulse voltammetric determination of selenocystine (SeC) using selenium‐gold film modified glassy carbon electrode ((Se‐Au)/GC) is presented. In 0.10 mol⋅L −1 KNO 3 (pH 3.20) solution, SeC yields a sensitive reduction peak at −740 mV on (Se‐Au)/GC electrode. The peak current has a linear relationship with the concentration of SeC in the range of 5.0×10 −8 –7.0×10 −4 mol⋅L −1 , and a 3σ detection limit of SeC is 3.0×10 −8 mol⋅L −1 . The relative standard deviation of the reduction current at SeC concentration of 10 −6 mol⋅L −1 is 3.88% ( n =8) using the same electrode, and 4.19% when using three modified electrodes prepared at different times. The content of SeC in the selenium‐enriched yeast and selenium‐enriched tea is determined. The total selenium in ordinary or selenium‐enriched tea is determined by DAN fluorescence method. The results indicate that in selenium‐enriched yeast about 20% of total selenium is present as SeC and in selenium‐enriched tea SeC is the major form of selenoamino acids. The total selenium content in selenium‐enriched tea soup is 0.09 μgSe/g accounting by 7% compared with that in selenium‐enriched tea. Hence, only a little amount of selenium is utilized by drinking tea, and most selenium still stay in tealeaf. Uncertainty are 22.4% and 16.1% for determination of SeC in selenium‐enriched yeast and selenium‐enriched tea by differential pulse voltammetry (DPV) on (Se‐Au)/GC electrode, respectively.