Acetic acid

Microcystin standards (MC-LR, MC-RR and MC-YR) with purities ≥95% were purchased from Alexis Biochemicals (Lausen, Switzerland). The stock solution of three MC congeners was prepared in 1 mL of Methanol solution at a concentration of 100 mg/L for each variant, which was kept at −20 °C for later use. The C18 solid phase extraction (SPE) cartridges (500 mg, 6 mL) used in MCs analysis were obtained from Anpel Company (Shanghai, China). The standard compounds GEO, MIB and 2-isobutyl-3-methoxypyrazine (IBMP, as the internal standard) were purchased from Sigma-Aldrich Chemical Co. (St. Louis, MO, USA) with the concentration of 100 mg/L in Methanol, while CYC and ION with purities ≥97% were purchased from Adamas Reagent Co., Ltd. (Basel, Switzerland). The stock solution of 1 mg/L with four target T&O compounds prepared in Methanol was stored in the dark at 4 °C. Sodium chloride (NaCl, Sigma, St. Louis, MO, USA) was added to the samples to enhance the T&O compounds extraction from water.
Methanol, trifluoracetic acid, acetic acid, acetonitrile and acetone were of HPLC grade from Tedia Company (Fairfield, OH, USA). Water used throughout the work was from a Milli-Q water purification system (Millipore, Billerica, MA, USA). All other reagents used were of analytical grade or better.

Acetonitrile, methanol, and formic acid were purchased from Darmstadt, Germany. Acetic acid was purchased from Tedia Co., Fairfield, OH, USA. A mixture of 18 external standards, including: C ((+)-catechin), GC ((−)-gallocatechin), EC ((−)-epicatechin), EGC ((−)-epigallocatechin), ECG ((−)-epicatechin gallate), EGCG ((−)-epigallocatechin gallate), theaflavin-3,3-digallate, gallic acid, theanine, phenylalanine, chlorogenic acid, caffeic acid, coumaric acid, rutin, trans-ferulic acid, sinapic acid, quercetin, naringenin, and kaempferol, with one internal standard 2′,7′-Dichlorofluorescein were used in this study. The internal standard used in this study was 2′,7′-Dichlorofluorescein. All the standards had a purity level higher than 95%. A detailed list of standards is provided in Table S3. All water used in the study was purified using a Milli-Q AdvantageA10 water purification system (Millipore Sigma, Burlington, MA, USA).

Acetonitrile and methanol of HPLC grade were supplied by Merck. Formic acid of HPLC grade was obtained from ROE. Acetic acid of chromatographic purity was purchased from TEDIA Co. Ltd. Ultrapure water was purified through a Milli-Q system. Omeprazole (99.9%, batch number: 100367–201305) and dextromethorphan (95.1%, batch number: 100201–201003) were purchased from China National Institutes for Food and Drug Control. Midazolam (99.8%, batch number: 20121213) was obtained from Shanghai Neuen Biology Technology Co. Ltd. Phenacetin (≥99%, batch number: 06 A 13) and tolbutamide (≥99%, batch number: 12 A 12) were purchased from Tianjin Semar Technology Co. Ltd. Diazepam (≥98%, batch number: H32020730) and propranolol hydrochloride (batch number: 100783–101202) as internal standards were obtained from Tianjin Silan Technology Co. Ltd and Chinese Food and Drug Test Institute, respectively. Metoprolol tartrate (batch number: 100084–201403) was purchased from Chinese Food and Drug Test Institute. O-demethylmetoprolol (batch number: 100084–201403) and α-hydroxymetoprolol (batch number: 1356–031A6) were obtained from Canada. Naoxintong capsule (batch number: 1608102) was supplied by Shanxi Buchang Pharmaceutical Co. Ltd.