Facile preparation of a sensitive electrochemical sensor with good performance for determination of methionine

In this work, a novel voltammetric sensor for detection of methionine was designed and prepared by using carbon paste electrode (CPE) modified with ZnO hollow quasi-spheres (ZnO hollow QSs) and 1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM.PF6). The results by cyclic voltammetry (CV) showed that the prepared electrode (ZnO-BMIM.PF6/CPE) effectively increased the oxidation peak current and reduced the oxidation peak potential of methionine, and had a suitable electrocatalytic activity for oxidation of methionine. Notably, the ZnO-BMIM.PF6/CPE exhibited high detection capability towards the quantification of methionine in 0.1 M PBS (pH = 7.0) over a concentration range from 0.04 µM to 330.0 µM with a limit of detection (LOD) of 0.02 μM. More importantly, the effectiveness of the ZnO-BMIM.PF6/CPE seneor was also confirmed in real sample (urine detection with acceptable recoveries (98.0-102.7%) and RSDs values ≤ 3.3%.