Magnesium chloride mgcl2

(-)-Epicatechin gallate (ECG, chromatographically pure) and (-)-epigallocatechin gallate (EGCG, chromatographically pure) were purchased from Taiyo Greenpower Co., Ltd. (Wuxi, China). Mucin (from the porcine stomach), (-)-epigallocatechin (EGC), (-)-epicatechin (EC), caffeic acid, chlorogenic acid, gallic acid and rutin were purchased from Sigma-Aldrich (Shanghai, China). Potassium chloride (KCl), calcium chloride (CaCl₂), magnesium chloride (MgCl₂) and aluminum chloride (AlCl₃) were all analytically pure and were obtained from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). We used a Hach TL2300 Turbidimeter (Shanghai, China). Tea samples were obtained from the Tea Research Institute, Chinese Academy of Agricultural Sciences (Hangzhou, China). The brewing water used was pure water obtained from Hangzhou Wahaha Group Co., Ltd. (Hangzhou, China).

Trimethoxyoctadecylsilane (C₂₁H₄₆O₃Si), bovine serum albumin (BSA) and tetracycline hydrochloride (C₂₂H₂₄N₂O₈·HCl) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Ampicillin, penicillin, streptomycin, kanamycin, dipotassium phosphate (K₂HPO₄), monopotassium phosphate (KH₂PO₄), sodium chloride (NaCl) and magnesium chloride (MgCl₂) were purchased from Sinopharm (Hong Kong, China). Tween-20 was purchased from Solarbio (Beijing, China). The filter paper was purchased from Whatman (Maidstone, UK). Tetracycline-BSA antigen and anti-tetracycline monoclonal antibody were purchased from Suzhou Kuaijiekang Co., Ltd. (Suzhou, China). Commercial tetracycline ELISA kit was purchased from Shenzhen Finder Biotech Co., Ltd. (Shenzhen, China). The heating plate (YH-946B) was purchased from Shanghai Yuxing Electronics Co., Ltd. (Shanghai, China). The inkjet printer (IP2780) was purchased from Canon (Tokyo, Japan).