Ammonium acetate

THI (99.65%, purity) and CLO (97.9%, purity) were manufactured by Dr. Ehrenstorfer GmbH (Augsburg, Germany) and were purchased from J&K Scientific Ltd. (Beijing, China). PYR (99.0%, purity) was purchased from Shanghai Pesticide Research Institute Co., Ltd. BF 500-3 (97.7%, purity) was purchased from Alta Scientific Co., Ltd. Acetonitrile and methanol of HPLC-grade were provided by Merck Co (Darmstadt, Germany). HPLC-grade formic acid (FA) was obtained from Anaqua Chemicals Supply (Wilmington, NC, USA) and ammonium acetate was purchased from Tedia Company (Fairfield, CA, USA). Analytical-grade acetonitrile was obtained from Shanghai Ling Feng Chemistry Reagent Co., Ltd. (Shanghai, China). Experimental water was obtained from Hangzhou QuChenShi Group Co., Ltd. (Hangzhou, China). Analytical-grade sodium chloride (NaCl) and anhydrous magnesium sulfate (MgSO₄) were purchased from Sinopharm Chemical Reagent (Beijing, China). Sorbent PSA was purchased from Agilent Technologies (Tianjin, China). Pesticide stock solutions were prepared at 1000 mg·L⁻¹ in HPLC-grade methanol and stored at 4 °C.

HCAs standards including, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline (7,8-DiMeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), 1-methyl-9H-pyrido[3,4-b]indole (Harman), 9H- Pyrido[4,3-b]indole (Norharman), 3-amino-1,4-Dimethyl-5H-pyrido[3,4-b]indole (Trp-P-1), 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), 2-amino-1-methyl-6-phenyl-Imidazo[4,5-b]pyridine (PhIP), 2-Amino-3-methyl-9H-pyrido[2,3-b]indole (MeAαC) and 2-amino-9H-pyrido[2,3-b]indole (AαC) were obtained from Toronto Research Chemicals (Downsview, ON, Canada). Trans fatty acid methyl ester (FAME) standards including, 9 t-14:1, 9 t-16:1, 6 t-18:1, 9 t-18:1, 11 t-18:1, 9 t,12 t-18:2, 11 t-20:1 and 13 t-22:1 were purchased from Nu-Chek Prep, Inc. (Elysian, MN, USA). The HPLC-grade solvents acetonitrile and methanol were bought from Tedia Co. (Fairfield, OH, USA), while ammonia, ammonium acetate, hydrochloric acid and sodium hydroxide were collected from Sinopharm Chemical Regent Co., Ltd. (Shanghai, China). All reagents and chemicals were chromatographic or analytical grade. A Millipore water purification system was used to collect the deionized water (Millipore Co., Bedford, MA, USA).

Acetonitrile, methanol and isopropanol (HPLC grade) were purchased from Merck (Darmstadt, Germany). Chloroform, formic acid, ammonium acetate and other solvents (analytical grade) were purchased from Tedia (Fairfield, CT, USA). Internal standard (L-2-chlorophenylalanine) was purchased from Sigma Aldrich (St. Louis, MO, USA).

The DMBZ bulk (batch nos. 20130323, 20130519, 20141001, 20180903, 20181001, and 20181003) was produced in Chizhou Dongsheng Pharmaceutical Co., Ltd. The six PGIs (impurities C–H) were obtained from Shenyang Manwei Chemical Co., Ltd. The purities of the compounds (>99%) used in this study were examined by using the appropriate HPLC methods. Ammonium acetate and formic acid were supplied by TEDIA Company, Inc. (Fairfield, OH, USA), and all reagents were HPLC-grade with ≥99% purity. MS-grade methanol was purchased from Mallinckrodt Baker Inc. (Phillipsburg, NJ, USA) and used to prepare the mobile phases. Ultrapure water was prepared from a Milli-Q water purification system (Bedford, MA, USA). The distilled water used was Wahaha purified water.

All analytes including Cap (Lot: J0713AS), 5'-DFCR (Lot: J1112AS), 5'-DFUR (Lot: J0713A), 2'-DFUR (Lot: J0620A), 5-FU (Lot: A0930AS), fludarabine (Fdb) (Lot: M0501AS) and 5-chlorouracil (5-ClU) (Lot: J1204A) but excepting FUH2 (Lot: 5-PTR-167-1) were purchased from Meilun Biotech Co., Ltd (Dalian City, China). FUH2 was supplied by Toronto Research Chemicals (Toronto, Canada). HPLC-grade acetonitrile was obtained from Merck (Merck Company, Darmstadt, Germany). HPLC-grade formic acid, dimethyl sulfoxide (DMSO), and ammonium acetate were purchased from Tedia Company Inc (Tedia, Fairfield, OH, USA). Ultrapurified water (0.22 µm filter membrane) was self-made in laboratory on a Milli-Q Reagent Water System (Millipore, MA) and was used throughout. HPLC-grade isopropanol and ethyl acetate were bought from Thermo fisher (Thermo Fisher Scientific, Waltham, MA) and Caledon laboratories (Caledon Laboratories Ltd, Georgetown, Canada). Human blank plasma was donated by Shanghai Red Cross Blood Center (Shanghai, China).

Paclitaxel, docetaxel, vinblastine, vinorelbine, pemetrexed, carboplatin, etoposide, cyclophosphamide, ifosfamide, gemcitabine, irinotecan, SN-38, and vindoline (internal standard, IS) were purchased from Sigma-Aldrich Corporation (St. Louis, MO, USA). All were corrected for purity and salt forms when weighed or diluted for standard stocks, whose chemical structures are shown in Figure 1. HPLC-grade methanol and acetonitrile were obtained from Merck Company (Darmstadt, Germany). HPLC-grade formic acid, dimethyl sulfoxide (DMSO), and ammonium acetate were purchased from the Tedia Company, Inc. (Fairfield, OH, USA). Ultra-purified water (0.22 μm) was self-made in the laboratory by a Milli-Q reagent water system (Merck KGaA, Darmstadt, Germany) and was used throughout. Waters Ostro 96-well plate (25 mg) was used for sample pretreatment (Waters, Milford, MA, USA). Human blank plasma was donated by Shanghai Red Cross Blood Center (Shanghai, China).

HPLC-grade methanol, methyl-tert-butylether (MTBE) and acetonitrile used for sample preparation were purchased from Merck (Darmstadt, Germany). The ultrapure water used for preparing the solutions and the mobile phase was purified by a Milli-Q system (Millipore, Burlington, MA, USA). Formic acid (Fluka, Darmstadt, Germany), ammonium bicarbonate (Sigma-Aldrich, St. Louis, MI, USA) and ammonium acetate (Tedia, Fairfield, OH, USA) were used as mobile phase additives. The internal standards were purchased from Isotec (Miamisburg, OH, USA) (leucine-d3, phenylalanine-d5), Sigma-Aldrich (USA) (D-camphor-10-sulfonic acid sodium salt, L-methionine sulfone, succinic acid-13C4, chenodeoxycholic acid-d4, cholic acid-d4, Alanine-d3), Cambridge isotope (Tewkesbury, MA, USA) (tryptophan-d5, FFA C16:0-d4), Avanti lipids (Alabaster, Al, USA) (LPC19:0), and ten Brink (Roden, The Netherlands) (FFA C22:0-d4).