Analisis Ion Nitrit (NO₂⁻) pada Aplikasi Silika Gel Termodifikasi GPTMS-DMA secara Kromatografi

The limited number of studies on the use of modified silica gel as a stationary phase in ion chromatography forms the background of this research, particularly for the analysis of nitrite ions (NO₂⁻), which are toxic and pose risks to both health and the environment. This study aims to apply glycidoxypropyltrimethoxysilane–dimethylamine (GPTMS–DMA) modified silica gel as a stationary phase for nitrite ion analysis. A quantitative experimental method was used with nitrite ion samples at concentrations of 100 ppm, 200 ppm, and 300 ppm. The analysis was conducted using a High Performance Liquid Chromatography (HPLC) system equipped with a UV detector and a mixed carbonate eluent (Na₂CO₃ and NaHCO₃) at concentrations of 0.1 M, 0.05 M, and 0.01 M. Results showed that 0.1 M Na₂CO₃ eluent produced the sharpest chromatogram peak, highest intensity, and stable baseline. The regression equation obtained was y = 0.0093x + 0.1533 with a coefficient of determination R² = 0.9939, indicating excellent linearity. The Limit of Detection (LOD) was 33.47 ppm, and the Limit of Quantification (LOQ) was 111.56 ppm, reflecting adequate sensitivity. The study concludes that GPTMS–DMA silica effectively enhances the sensitivity and selectivity of nitrite ion analysis and holds potential for further application in the analysis of other inorganic ions.