Analisis Kafein Dengan Elektroda Composite Ptfe/Grafit/Kompleks-Co(II) Kafein Secara Flow Injection Potentiometry: Pengaruh PH Buffer Terhadap Kinerja Sensor

Abstract

The effect of buffer pH on caffeine analysis was investigated using a PTFE/Graphite/Co(II)-Caffeine complex electrode via Flow Injection Potentiometry (FIP). Optimization of the buffer pH was conducted to determine its influence on the potential response of the electrode. The procedure involved fabricating the PTFE/Graphite/Co(II)-Caffeine complex electrode using an optimal composition of 0.2 gram for each component and analyzing caffeine across various buffer pH levels. Optimal buffer pH values, based on the observed potential responses, were identified as acetate buffer pH 5 (17 mV), phosphate buffer pH 4.5 (17 mV), and sulfate buffer pH 3.5 (17.5 mV). Subsequently, the electrode's performance was evaluated using these three optimal buffers. Among the three, acetate buffer pH 5 demonstrated the highest sensitivity (-7.4395 mV/decade) and a linearity of 0.9939. The %RSD values obtained for all three optimal buffers met precision requirements (< 5%), indicating consistent, reproducible results. Based on these parameters, acetate buffer pH 5 proved superior due to its greater sensitivity and linearity in response to changes in caffeine concentration.