Sensitivitas dan Limit Deteksi Elektroda Termodifikasi Kitosan/GQDs/Fe3O4 dalam Mengukur Konsentrasi Kolesterol Menggunakan Metode Voltametri Siklik

Abstract

In this research, the chitosan/GQDs/Fe3O4 modified electrode has been successfully carried out in measuring cholesterol using the cyclic voltammetry method. The chitosan/GQDs/Fe3O4 modified electrode was fabricated using the electrodeposition method using a ratio of 2:1:1 using 1.5% chitosan, GQDs 250 mg/L, and Fe3O4 variations of 50, 75, 100, 125, and 150 mg/L. Surface analysis of the modified electrode was carried out using the Fourier Transform Infra-Red (FT-IR), Field Emission-Scanning Electron Microscopy (FE-SEM), and X-Ray Diffraction (XRD) methods. Testing the sensing properties of the chitosan/GQDs/Fe3O4 modified electrode was carried out using the cyclic voltammetry method using voltage range parameters of -1V to +1V and a scan rate of 125 mV/s. Testing was carried out with variations of cholesterol of 50, 100, 150, 200, 250, and 300 mg/dL and blood serum dissolved in phosphate buffer solution. The results of the test produced a Chitosan/GQDs/Fe3O4 modified electrode with an Fe3O4 concentration of 100 mg/L which is an electrode with good performance. The limit of detection (LOD) and Limit of quantitation (LOQ) in cholesterol detection were 15,24 mg/dL and 50,81 mg/dL. In real sample testing, the modified electrode was also considered capable of detecting cholesterol in blood serum. This is evidenced by the obtained percentage errors, which were 0.88% for serum A, 1.01% for serum B, 0.54% for serum C, and 1.32% for serum D. Therefore, the chitosan/GQDs/Fe3O4 modified electrode can be further applied as a working electrode material for electrochemical sensors in cholesterol detection.