Tryptophan d5

The substances 1-Methylhistidine, adenine, adenosine, arginine, azelaic acid, chenodeoxycholic acid, cholic acid, citrulline, cortisol, cortisone, creatinine, deoxycholic acid, glutaric acid, glycocholic acid, hippuric acid, inosine, isoleucine, leucine, l-pyroglutamic acid, methionine, methylmalonic acid, mevalonolactone, N,N-dimethylglycine, nicotinic acid, p-aminobenzoic acid, phenylalanine, proline, raffinose, riboflavin, taurine, taurocholic acid, tryptophan, and uracil were purchased from Sigma-Aldrich (Buchs, Switzerland). Deuterated and heavy-labeled internal standards (IS) adenosine ribose-D1, arginine-13C6, caffeine 3-methyl-13C, carnitine trimethyl-D9, creatinine N-methyl-D3, deoxycholic acid-D4, D-fructose 13C, glycine-13C2, glycocholic acid-D4, hippuric acid 15N, kynurenine-D4, leucine-D10, lysine-D4, phenylalanine-D1, proline 15N, serine-D3, tryptophan-D5 and uric acid-15N2 were purchased from Cambridge Isotope Laboratories (Cambridge, MA, USA), and were delivered by ReseaChem Life Science (Burgdorf, Switzerland) or Sigma-Aldrich (Buchs, Switzerland). Water, acetonitrile (ACN), methanol (MeOH) of HPLC grade were obtained from Fluka (Buchs, Switzerland). All other chemicals used were from Merck (Zug, Switzerland) and were of the highest grade available.

Ammonium acetate, LC-MS-grade formic acid (FA), isopropanol and acetonitrile, and HPLC-grade methanol and methyl tert-butyl ether (MTBE) were purchased from Fisher Scientific (Geel, Belgium). Lipidomics Isotope-labelled internal standards (13 (link)) and Lyso-phosphatidylcholine (LPC) 19:0 (for metabolomics analysis) were purchased from Avanti Polar Lipids (Alabaster, AL, USA). Isotope-labeled internal standards for metabolomics analysis, including tryptophan-d5, valine-d8, phenylalanine-d5, palmitic acid-d3, cholic acid-d4, stearic acid-d3, carnitine C8:0-d3, and carnitine C16:0-d3, were obtained from Cambridge Isotope Laboratories (Tewksbury, MA, USA). Ultrapure water was prepared using the Milli-Q system (Millipore, Billerica, USA).

Formic acid (FA), acetonitrile (ACN), and ammonium acetate (NH4OAc) were obtained from Thermo Fisher, United States. Tryptophan-d5, valine-d8, carnitine C8:0-d3, carnitine C16:0-d3, cholic acid-d4, and stearic acid-d3 (98% purity) were purchased from Cambridge Isotope Laboratories (Tewksbury, MA, United States). Lysophosphatidylcholine LPC (19:0) was obtained from Avanti Polar Lipids (Alabaster, AL, United States). Pure water was purchased from Wahaha ((Hangzhou, China).