Disodium hydrogen phosphate

Acetonitrile, methanol, and acetic acid were chromatographically pure and purchased from Tedia, Fairfield, OH, USA; o-phthalaldehyde (OPA), methyl chloroformate (FMOC), gallic acid, 8 catechin monomers, 3 alkaloid monomers, 16 kinds of flavonoids, and 20 kinds of amino acid standards were purchased from Shanghai Yuanye Biotechnology Co., Ltd. (Shanghai, China); and potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium potassium tartrate, ferrous sulfate, and anthrone were analytically pure and purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China).

(‐)‐Catechin (C), (‐)‐epigallocatechin (EGC), (‐)‐gallocatechin (GC), (‐)‐epicatechin (EC), (‐)‐epicatechin gallate (ECG), (‐)‐epigallocatechin gallate (EGCG), (‐)‐gallocatechin gallate (GCG), anhydrous glucose, caffeine (CAF), and gallic acid (GA) were purchased from Shanghai Yuanye Biotechnology Co., Ltd. Company (Shanghai, China). Alanine (ala), arginine (arg), aspartic acid (asp), cysteine (cys), glutamic acid (glu), glycine (gly), histidine (his), isoleucine (ile), leucine (leu), methionine (met), phenylalanine (phe), proline (pro), serine (ser), threonine (thr), tryptophan (trp), tyrosine (tyr), valine (val), theanine, the AccQ‐Fluor Reagent Kit, and AccQ‐Tag eluent were purchased from BDH Chemicals Ltd. (Poole, UK). Acetonitrile (chromatographically pure), sodium carbonate, methanol (chromatographically pure), concentrated sulfuric acid, anthrone, ferrous tartrate (analytically pure), disodium hydrogen phosphate, and potassium dihydrogen phosphate were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Pure water from China Resources C'estbon Beverage Co., Ltd. (Shenzhen, China) was used throughout the study.

Poly(dimethyldiallylammonium chloride) (PDMDAAC) was supplied by Aldrich Co., Ltd (Shanghai, China). Cellulose sulfate sodium salt was purchased from J&K SCIENTIFIC LTD (Shanghai, China). Borax and sodium nitrite were purchased from Hunan General Chemical Reagent Works (Changsha, China). Potassium ferricyanide, potassium hexacyanoferrate, sodium dihydrogen phosphate and disodium hydrogen phosphate were all bought from Sinopharm Chemical Reagent Co., Ltd (Shanghai, China). All the chemicals were of analytical reagent grade and were used as received without any further purification. Both PDMDAAC and NaCS were also synthesized in our experiments (details can be seen in the Supporting Information).

Patulin (purity ≥ 98.0%) was purchased from Sangon Biotech (Shanghai, China) Co., and Ltd. L-cysteine (purity ≥ 99.0%) was purchased from the Aladdin Industrial Corporation (Shanghai, China). Acetonitrile (HPLC grade) was obtained from Oceanpak Alexative Chemical Co., Ltd. (Goteborg, Sweden). Formic acid (HPLC grade) was provided by Anpel Laboratory Technologies Inc. (Shanghai, China). Ethyl acetate, disodium hydrogen phosphate, and citric acid were all analytical grade and purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China).

AChE (from electric eel), ATCl, AgNWs and DDVP were from Sigma-Aldrich. CS (viscosity > 400 mPa s) and Gra (stripped by 1-methyl-2-pyrrolidinone (NMP)) were from Aladdin Bio-Chem Technology (Shanghai, China). Glucose was from Sangon Biotech (Shanghai, China), ethanol absolute, glacial acetic acid, tetra-n-butyl titanate, hydrochloric acid, N,N-dimethylformamide (DMF), isopropanol, potassium ferricyanide, potassium ferrocyanide trihydrate, potassium chloride, sodium chloride, sodium dihydrogen phosphate, disodium hydrogen phosphate were from Sinopharm Chemical Reagent Co., Ltd (Shanghai, China). All chemical reagents used are of analytical grade. Nitrogen with a purity of 99.9% comes from Air Liquide (China) Holding Co., Ltd. The deionized water (DI water) used in the whole experiment was obtained by ion exchange method. Vegetable juice is a supernatant obtained by washing, grinding, filtering, and centrifuging fresh lettuce purchased from a nearby vegetable market (ESI†).