Glycodeoxycholic acid (GDCA) is a glycine-conjugated form of the secondary bile acid deoxycholic acid .¹ It induces a reversible, concentration-dependent reduction in myogenic tone in rats and decreases expression of the gene encoding the cytochrome P450 (CYP) isoform 7A1 (CYP7A1) in rabbits.^2,3 Serum levels of GDCA are elevated in non-surviving patients with acetaminophen-induced acute liver failure (AALF) compared with survivors.⁴ GDCA levels are also increased in the plasma of patients with asthma.⁵ GDCA MaxSpec® standard is a quantitative grade standard of glycodeoxycholic acid that has been prepared specifically for mass spectrometry and related applications where quantitative reproducibility is required. The solution has been prepared gravimetrically and is supplied in a deactivated glass ampule sealed under argon. The concentration was verified by comparison to an independently prepared calibration standard. The verified concentration is provided on the certificate of analysis. This GDCA MaxSpec® standard is guaranteed to meet identity, purity, stability, and concentration specifications and is provided with a batch-specific certificate of analysis. Ongoing stability testing is performed to ensure the concentration remains accurate throughout the shelf life of the product. Note: The amount of solution added to the vial is in excess of the listed amount. Therefore, it is necessary to accurately measure volumes for preparation of calibration standards. Follow recommended storage and handling conditions to maintain product quality.