Prostaglandin D2 (PGD2) is the major eicosanoid product of mast cells and is released in large quantities during allergic and asthmatic anaphylaxis. Mastocytosis patients produce excessive amounts of PGD2, which causes vasodilation, flushing, hypotension, and syncopal episodes. PGD2 is also produced in the brain via an alternative pathway involving a soluble, secreted PGD-synthase also known as beta-trace. In the brain, PGD2 produces normal physiological sleep and lowering of body temperature. Further pharmacological actions include inhibition of platelet aggregation and relaxation of vascular smooth muscle. PGD2 inhibits human ovarian tumor cell proliferation with an IC50 value of 6.8 µM. PGD2 MaxSpec(R) standard is a quantitative grade standard of PGD2 (Cay-12010) that has been prepared specifically for mass spectrometry or any application 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. This PGD2 MaxSpec(R) 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.