Pengembangan Elektroda Potensiometri Berbasis Komposit Epoxy-Graphite-Cobalt Oxide untuk Pengukuran Fosfat

Abstract

Phosphate is an essential nutrient in soil, playing a crucial role in photosynthesis and root development in plants. Phosphate is capable of activating various plant metabolic enzymes and is also a component of chlorophyll. Phosphate content analysis is conducted to assess soil fertility through quantitative measurements, one is the potentiometric method using an epoxy-graphite-CoO composite electrode. These objectives highlight the study's focus on optimizing the electrode’s physical properties for improved ion sensitivity and accuracy. Additionally, the research aims to validate the electrode's efficiency in real sample analyses, providing insights into its suitability for practical applications in soil phosphate measurement. This electrode was fabricated using a mixture of epoxy, graphite, and cobalt oxide (CoO) in various composition and thickness variations to determine the optimal configuration. Optimization results indicated that the best electrode composition was a 3:1 ratio of graphite to CoO with a thickness of 3 mm. Characterization of the optimized composite electrode showed a linearity value of 0.9924, sensitivity of -79.689 mV/decade, detection limit of 2.768 x 10⁻⁶ M, precision of 0.1055%, and reproducibility of 2.416%. The electrode was then applied to determine the phosphorus (P₂O₅) content in soil samples from a citrus orchard in Suci Village, Panti District, Jember Regency, showing a phosphate content of 0.0022 g/L. The recovery value obtained was 98.83%, meeting the expected range for a valid analytical method. Based on electrode performance parameters such as linearity, sensitivity, detection limit, precision, and reproducibility, this epoxy-graphite-CoO composite electrode demonstrates adequate performance and can be used for phosphate analysis in soil.