Simple colorimetric monitoring of chlorogenic acid in coffee washing water using Ag-modified faujasite zeolite
摘要
Silver-based materials are widely recognized for their optical, electronic, and chemical properties, which make them attractive for sensing applications. Among these materials, silver-modified zeolites stand out due to their high surface area, chemical and dispersion stability, and the possibility of tailoring surface interactions to improve affinity toward specific analytes. In this study, a faujasite zeolite framework modified with silver ions (AgFAU) is investigated for colorimetric sensing of chlorogenic acid (CGA). The detection was carried out using a digital image colorimetry (DIC) approach, in which red, green, and blue (RGB) parameters were used for the quantitative optical analysis of colored dispersions. Based on the DIC analysis, CGA could be quantitatively monitored in the concentration range of 1–20 mg L−1, with a limit of detection in the range of 0.47–1.17 mg L−1 (average, 0.8 ± 0.3 mg L−1), consistent with values reported for similar colorimetric sensors. The proposed approach was successfully applied to the detection of CGA in coffee wastewater. In addition, the system showed good specificity toward structurally related polyphenols and high reproducibility (RSD ≤ 6%), demonstrating its suitability as a simple and easy-to-interpret strategy for CGA monitoring.