Glutamine

HPLC-grade formic acid was obtained from Sigma-Aldrich (USA). HPLC/MS-grade formic acid, ammonium formate, and acetonitrile were acquired from Fisher Scientific (USA). The internal standards Labeled Carnitine Standards (L-carnitine (N-trimethyl-D₉), L-acetylcarnitine (N-methyl-D₃), L-propionylcarnitine (Nimethyl-D₃), L-butyrylcarnitine (N-methyl-D₃), L-isovalerylcarnitine (N-trimethyl-D₉), L-octanoylcarnitine (N-methyl-D₃), L-myristoylcarnitine (N-trimethyl-D₉), L-palmitoylcarnitine (N-methyl-D₃)) were attained from Cambridge Isotope Laboratories. Seventeen amino acid standards (alanine, valine, leucine, isoleucine, phenylalanine, methionine, proline, glycine, serine, threonine, cysteine, tyrosine, histidine, lysine, arginine, aspartic acid, glutamic acid) were purchased from Sigma-Aldrich. Eight amino acid standards (tryptophan, asparaginate, glutamine, ornithine, taurine, citrulline, cysteine, γ-aminobutyric acid) were gained from J&K Scientific. Ultrahigh purity water was prepared by Millipore-Q Water Purification System (Millipore, Germany).

Fatty acid-free HSA (A1887, ≤0.007% fatty acids) was purchased from Sigma Chemical Company (St Louis, USA). Trametinib (99% purity) was obtained from Shanghai Rongtai Pharmatech Co. Ltd (Shanghai, China). Dansylsarcosine (98%) was acquired from Heowns Biochem Technologies LLC (Tianjin, China). Warfarin sodium (98%), phenylbutazone (99%), ibuprofen (98%), glutamine (99%), alanine (99%), glycine (99%), and valine (99%) were purchased from J&K Scientific Ltd (Beijing, China). Phosphate buffer saline (pH = 7.4) was used in this study.