Ammonium bicarbonate

The standards which included glycyrrhizic acid, glycyrrhetinic acid, dehydrotumulosic acid, isoliquiritin, liquiritin, atractylenolide III, cinnamic acid, and schisandrin (≥98% purity) were all procured from Hongyong Biotechnology Co., Ltd. (Shanghai, China). Sulfatase was procured from Helix pomatia (Type H-1, Sulfatase ≥10, 000 units/g solid, Sigma, United States). The peptides LTIIPQDPILFSGSLR, GVALPETIEEAENLGR, AAATEDATPAALEK, TFQFPGDIESSK, LLLSGFQEELR, STALQLIQR, NTTGALTTR, EENLGITK, SVQPELK, and TYPVPFQR, as well as stable isotope-labeled internal standards (≥98% purity) were synthesized by Bankpeptide Biological Technology, Co., Ltd. (Hefei, China). The ProteoExtract Native Membrane Protein Extraction Kit was purchased from Merck KGaA (Darmstadt, Germany). The BCA Protein Assay Kit and In-Solution Tryptic Digestion Kit were obtained from Pierce Biotechnology (Rockford, IL, United States). Formic acid dedicated to mass spectrometry (99% purity); ammonium bicarbonate (98% purity); and sodium deoxycholate (98% purity) were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Acetonitrile and methanol, both MS grades, were obtained from Merck KGaA (Darmstadt, Germany).

The GMDTC (purity > 95% by HPLC-UV, content > 80% by NMR) was synthesized at Asymchem Laboratories (Tianjin) Co., Ltd. (Tianjin, China). The metolazone (99.88%), used as the internal standard (IS), was purchased from Dalian Meilun Biotech Co., Ltd. (Dalian, China). The methanol and acetonitrile for the gradient HPLC was purchased from Thermo Fisher Scientific Inc. (Tustin, CA, USA). Ammonium bicarbonate, ammonia, and disodium dihydrogen ethylenediaminetetraacetate were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China.).