Table 5.
Internal standards, with concentrations in ISTD MIX, acquired for quality control and for quantitation.
| Internal Standard | Abbreviation | Group | Vendor | Solvent, Stock Solution | Concentration in ISTD MIX (ng mL−1) |
|---|---|---|---|---|---|
| d5-Glutamine | d5-Gln | Amino acids + related metabolites | CIL | H2O | 30,000 |
| d10-L-Leucine | d10-Leu | CDN | 0.1 M HCl | 5000 | |
| 2H4-L-Homocitrulline | 2H4-HCit | Alsachim | |||
| Glycine-1-13C,2,2-d2 | 13C, d2-Gly | Sigma-Aldrich | |||
| d4-DL-Alanine | d4-Ala | ||||
| d5-L-Glutamic Acid | d5-Glu | ||||
| d10-Isoleucine | d10-Ile | CIL | |||
| d5-L-Phenylalanine | d5-Phe | 500 | |||
| d8-Tryptophan | d8-Trp | 5000 | |||
| d7-Tyrosine | d7-Tyr | ||||
| d4-Citrulline | d4-Cit | 500 | |||
| d3-L-2-Aminoadipic Acid | d3-AADA | 10,000 | |||
| d7-Asymmetric dimethylarginine | d7-ADMA | 5000 | |||
| 13C6-Kynurenine | 13C6-Kynu | Alsachim | 30,000 | ||
| d4-Taurine | d4-Taurine | 500 | |||
| d4-Deoxycholic Acid | d4-DCA | Bile acids | CDN | MeOH | 500 |
| d4-Glycocholic Acid | d4-GCA | 250 | |||
| d4-Deoxychenocholic Acid | d4-CDCA | 500 | |||
| d4-Glycoursodeoxycholic Acid | d4-GUDCA | 5000 | |||
| d4-Cholic Acid | d4-CA | 500 | |||
| d4-Ursodeoxycholic Acid | d4-UDCA | 250 | |||
| d4-Glychochenodeoxycholic Acid | d4-GCDCA | CIL | 5000 | ||
| d6-Glycodeoxycholic Acid | d6-GDCA | 30,000 | |||
| d9-Taurochenodeoxycholic Acid | d9-TCDCA | 500 | |||
| d4-Taurocholic Acid | d4-TCA | ||||
| d4-Tauroursodeoxycholic Acid | d4-TUDCA | 250 | |||
| d5-Creatinine | d5-Crea | Polar metabolites | CDN | 10% MeOH | 10,000 |
| d4-N-methyl-nicotinamide | d4-N-MNA | 250 | |||
| d9-Gamma-butyrobetaine | d9-GBB | 500 | |||
| d4-Indoxyl Sulfate | d4-IndS | Sigma-Aldrich | 5000 | ||
| d14-Azelaic Acid | d14-AzelA | Small organic acids | CDN | MeOH | 5000 |
| d4-3-Hydroxybutyric Acid | d4-β-OHB | 10% MeOH | 100,000 | ||
| d3-2-Hydroxybutyric Acid | d3-α-OHB |
Vendor information: Sigma-Aldrich (Steinheim, Germany); CDN: C/D/N Isotopes, Inc. (Quebec, Canada); CIL: Cambridge Isotope Laboratories Inc. (Tewksbury, MA, USA); Alsachim (Illkirch Graffenstaden, France); SCB: Santa Cruz Biotechnology, Inc. (Dallas, TX, USA).