Notes: Prostaglandin D2 dopamine-d4 (PGD2 dopamine-d4) is intended for use as an internal standard for the quantification of PGD2 dopamine (Item No. 9002504) by GC- or LC-mass spectrometry. PGD2 dopamine is a conjugate of the neurotransmitter dopamine and PGD2 that can be used to study the biological function of PGD2 in the brain and periphery.