*2.1. Chemicals and Reagents*

Silver nitrate (AgNO3, 99.7%) and R6G (95.0%) were purchased from Energy Chemical Co., Ltd. (Shanghai, China). Sodium citrate (99.0%) was purchased from Innochem Co., Ltd. (Beijing, China). PDMS Sylgard 184 was supplied by Dow Corning Corporation (Midland, MI, USA). (3-Aminopropyl) triethoxysilane (APTES, 99.0%) was obtained from Macklin Biochemical Co., Ltd. (Shanghai, China). Malathion (purity: 98.33%, expanded uncertainty: 0.48%), phoxim (purity: 97.26%, expanded uncertainty: 0.72%), and thiram (purity: 98.36%, expanded uncertainty: 0.56%) certified reference materials were purchased from LGC Standards GmbH (Wesel, Germany). Methanol and acetonitrile were supplied by Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Deionized water was supplied by Titanchem Co., Ltd. (Shanghai, China) and used without further purification throughout the experiment.
