Table 1.

Standard compounds acquired for quality control and for quantitation.

Compound	Abbreviation	Group	Vendor	Solvent, Stock Solution
L-Glutamine	Gln	Amino acids + related metabolites	Sigma-Aldrich	H2O
Glycine	Gly			0.1 M HCl
L-Alanine	Ala
L-Leucine	Leu
L-Isoleucine	Ile
L-Phenylalanine	Phe
L-Tryptophan	Trp
L-Tyrosine	Tyr
L-Glutamic Acid	Glu
L-Citrulline	Cit
L-Homocitrulline	HCit		SCB
Asymmetric dimethylarginine	ADMA
Symmetric dimethylarginine	SDMA
DL-2-Aminoadipic Acid	AADA		Sigma-Aldrich
L-Kynurenine	Kynu
Taurine	Taurine
Deoxycholic Acid	DCA	Bile acids	Sigma-Aldrich	MeOH
Glycochenodeoxycholic Acid	GCDCA
Glycodeoxycholic Acid	GDCA
Glycocholic Acid	GCA
Taurodeoxycholic Acid	TDCA
Taurochenodeoxycholic Acid	TCDCA
Deoxychenocholic Acid	CDCA
Cholic Acid	CA
Taurocholic Acid	TCA
Glycoursodeoxycholic Acid	GUDCA		CIL
Ursodeoxycholic Acid	UDCA
Tauroursodeoxycholic Acid	TUDCA
Creatinine	Crea	Other metabolites	Sigma-Aldrich	10% MeOH
Indoxyl Sulfate	IndS
N-methyl-nicotinamide	N-MNA		SCB
Gamma-butyrobetaine	GBB
Azelaic Acid	AzelA	Small organic acids	Sigma-Aldrich	MeOH
L-3-hydroxybutyric Acid	β-OHB			10% MeOH
R-2-hydroxybutyric Acid	α(R)-OHB
S-2-hydroxybutyric Acid	α(S)-OHB

Vendor information: Sigma-Aldrich (Steinheim, Germany); SCB: Santa Cruz Biotechnology, Inc. (Dallas, TX, USA); CIL: Cambridge Isotope Laboratories Inc. (Tewksbury, MA, USA).