Hippuric acid

Lead nitrate (Pb(NO₃)₂), sodium lauryl sulfate, creatinine anhydrous, propionic acid, lithium d-, and l-lactate, acetylacetone, 37% formaldehyde, cimetidine, indoleacetic acid, methylumbelliferone, and methylumbelliferyl N-acetyl-β-d-glucosaminide were purchased from Sigma-Aldrich Fine Chemicals Inc. (MO, USA). Formic acid, HPLC grade acetonitrile (ACN), ethanol and methanol (MeOH) were purchased from Merck (Darmstadt, Germany). Hippuric acid, 2,2′-dipyridyl disulfate (DPDS), triphenylphosphine (TPP) and 4-nitro-7-piperazino-2,1,3-benzoxadiazole (NBD-PZ) were purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan). 5-Aminolevulinic acid hydrochloride and guanidinoacetic acid were purchased from Alfa Aesar (MA, USA). Sulbactam was purchased from Cayman Chemical (Michigan, USA). Acetic acid was purchased from Hayashi Pure Chemical Ind.,Ltd. (Osaka, Japan). Trifluoroacetic acid (TFA) was purchased from Riedel-de Haën (Seelze, Germany). 3-(Trimethylsilyl)propionic-2,2,3,3-d₄ acid sodium salt (TSP) was purchased from Cambridge Isotope Laboratories (MA, USA). 1,1-Dimethylbiguanide hydrochloride (metformin) was purchased from Santa Cruz Biotechnology, Inc. (Texas, USA). Protein Assay Dye Reagent was purchased from Bio-Rad Laboratories (California, USA).

Indoxyl sulfate was purchased from Biosynth (Staad, Switzerland). p-Cresyl sulfate and phenyl sulfate were synthesized at Eiweiss (Shizuoka, Japan). Hippuric acid and indoleacetic acid were purchased from Tokyo chemical industry (Tokyo, Japan). N-Acetyl-L-cysteine was purchased from Sigma (St. Louis, MO, USA).