Highly sensitive electrochemical sensor for tyrosine detection using a sub-millimeter electrode

In recent years, small-sized electrodes have drawn widespread attraction in electroanalysis due to high sensitivity, rapid response and low cost. Hereby, a sub-millimeter paste electrode with inner diameter of 0.8 mm was prepared by combining the excellent properties of reduced graphene oxide (rGO) and acetylene black (AB), and the electrochemical behavior of tyrosine (Tyr) on the modified electrode (denoted as rGO/ABPE) was investigated in detail. The electrochemical responses obtained on the sub-millimeter rGO/ABPE were compared with that obtained on a conventional size electrode with diameter of 3 mm. The results showed that the 0.8 mm one has better performance than that of 3 mm. Compared with the paste electrode made of graphite powder, the oxidation peak current of Tyr increased significantly due to the synergistic effect of rGO and AB. Under the optimized experimental conditions, the calibration curve of Tyr showed a linear relationship between 0.1 and 100 ?M (R = 0.9995) with good sensitivity of 3.314 ?A ?M-1 cm-2, and the detection limit was 0.06 ?M. By comparison with conventional size electrode, the detection of Tyr on the sub-millimeter electrode shows higher sensitivity, wider linear range and lower detection limit. In addition, the excellent reproducibility, stability and selectivity of the sub-millimeter rGO/ABPE make it suitable for Tyr analysis in both food and biological samples.