CARBON PASTE ELECTRODE MODIFIED WITH POLY(GLUTAMIC ACID) AND SODIUM DODECYL SULFATE FOR DETERMINATION OF CAPSAICIN BY VOLTAMMETRIC METHODS

• Main Author: Aristo Paskhalis, Yeremia
• Format: Final Project
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/83243
• Institution: Institut Teknologi Bandung

Capsaicin is a member of the capsaicinoid group of compounds responsible for the spiciness of chili peppers. The concentration of capsaicin found in water at Xiamen Port, China, is about 13.03 ?M, which can impact marine life. Therefore, to measure capsaicin at the desired detection limit, an analytical method is needed, one of which is voltammetry. Carbon paste electrodes (CPE) are carbon-based electrodes that are inexpensive but have low sensitivity, thus requiring modification. In this study, CPE was modified by electropolymerizing glutamic acid and sodium dodecyl sulfate (SDS) on the surface of the CPE to enhance sensitivity. This enhancement is due to specific interactions between polyglutamic acid (PAG) and capsaicin as well as the role of SDS in shifting the oxidation potential of glutamic acid and cleaning residues from the CPE surface, allowing glutamic acid to adhere effectively before electropolymerization occurs. This study aims to modify CPE with PAG and SDS for the voltammetric analysis of capsaicin. The parameters used and varied include the optimal number of electropolymerization cycles, SDS concentration, pH value, and the voltammetry technique used. Phosphate buffer electrolyte solution was chosen because it has good solubility with capsaicin. The results showed that the optimal modification of CPE with PAG and SDS was achieved by electropolymerization using cyclic voltammetry for 8 cycles with a PAG composition of 10:10 mM. This optimal condition was chosen based on the electrode's performance, which had the highest oxidation peak current when measuring 100 ?M capsaicin. The optimal measurement conditions were obtained in a pH 6 solution using the square wave voltammetry technique. Scan rate analysis in the potential range of 10-500 mV/s indicated that the process occurring on the electrode surface is controlled by adsorption. The electrode performance was determined by the repeatability of capsaicin measurements using one CPE (relative standard deviation of 4.58%) and the reproducibility of five CPEs (relative standard deviation of 3.06%). The modified CPE had three linear concentration ranges, namely 1-10 ?M (R² 0.9944), 10-100 ?M (R² 0.9902), and 100-1000 ?M (R² 0.9913). The detection limit of the measurement was 0.49 ?M. The measurement of capsaicin in artificial samples showed a recovery of 103.38% using the voltammetry method, while the HPLC method showed 103.35%. The T-test and F-test results indicated that there were no significant differences between the two methods.