Methanol

Chloroauric acid tetrahydrate (HAuCl₄·4H₂O, >47.8%), formic acid, methanol, and ethanol with the analytical grade were purchased from the Sinopharm Chemical Reagent Co., Ltd., Shanghai, China, N,N-dimethylformamide (DMF) was obtained from ANPEL Laboratory Technologies (Shanghai) Inc., Shanghai, China, Polyvinylpyrrolidone (PVP, Mw 40,000) were purchased from Solarbo Life Sciences Inc. (Beijing, China). Tetramethylthiuram disulfide (thiram) (100 mg, Dr. Ehrenstorfer) was selected as model probed molecule, which was purchased from J&K scientific Ltd. (Beijing, China) and the corresponding standard solutions (C = 100 ng·mL⁻¹) were diluted with methanol. Two representative dioxin compounds (2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD and 3,3′,4,4′-Tetrachlorobiphenyl, PCB-77) were prepared with methanol (C = 10 ng·mL⁻¹). The analysis solution of 1,1-bis (4-hydroxyphenyl) ethane (BPE, C = 100 μg·mL⁻¹, methanol) was purchased from J&K scientific Ltd. (Beijing, China) and diluted to the certain concentration (C = 1 μg·mL⁻¹) with methanol solution. Seven kinds of antibiotic residues (tetracycline, doxycycline, chlortetracycline, ciprofloxacin, enrofloxacin, sulfamethazine, and sulfacetamide) were prepared with methanol solution (C = 1 μg·mL⁻¹).

A Nafion-117 cation exchange membrane for separating catholyte and anolyte was manufactured by Du Pont de Nemours & Co., Ltd. (Wilmington, DE, USA). A potentiostat providing direct current (DC) power was purchased from Shanghai Chenhua Science Technology Corp., Ltd., Shanghai, China. Unless otherwise specified, all chemical reagents were acquired from commercial suppliers and utilized without further purification. Sodium persulfate (PS, ≥99.5%), carbamazepine, norfloxacin, atrazine, phonel, methanol (99%), bisphenol A (BPA), sodium hydroxide (NaOH), atrazine, sulfuric acid (H₂SO₄), sodium sulfate (Na₂SO₄, ≥99.0%), Diammonium 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate) (ABTS), potassium titanium (IV) oxalate, tert-butanol (TBA, 99%), and boron-doped diamond electrode (BDD) electrodes (800 ppm boron, bipolar, 1 mm coating thickness) were obtained from J&K Chemical (Beijing, China). Activated carbon fiber (ACF) electrodes and platinum-plated titanium electrodes (25 mm × 50 mm × 1 mm) were obtained from Shanxi Kaida Chemical Ltd., Lvliang, China. DC power supply was obtained from Zhejiang Sako Electrical Group Co., Ltd., Leqing, China.

The materials and reagents are as follows: 2-Methylimidazole (99%, J&K, Beijing, China), thiourea (99%, J&K, Beijing, China), potassium bromide (99%, J&K, Beijing, China), zinc dihydrate acetate (99%, J&K, Beijing, China), sodium sulfate (99%, J&K, Beijing, China), disodium ethylenediaminetetraacetic acid (EDTA) (99%, J&K, Beijing, China), benzoquinone (99%, J&K, Beijing, China), methanol (≥99.7%, J&K, Beijing, China), isopropanol (99.5%, J&K, Beijing, China), Rhodamine B (96%, J&K, Beijing, China), anhydrous ethanol (≥99.7%, Fuyu chemical, Tianjin, China), cobalt nitrate hexahydrate (98%, Damao chemical reagent factory, Tianjin, China), and cadmium acetate dihydrate (99%, Thermo Fisher Scientific, Waltham, MA, USA). The ITO slides are purchased from Luoyang Guluo Glas Co., Ltd. (Luoyang, China).