Notes: The prostaglandin F2α (PGF2α) Quant-PAK has been designed for the convenient, precise quantification of PGF2α by GC- or LC-mass spectrometry. It includes a 50 µg vial of PGF2α-d4 and a precisely weighed vial of unlabeled PGF2α, with the precise weight (5 mg) indicated on the vial. This unlabeled PGF2α can be used to quantify the PGF2α-d4 standard by constructing a standard curve of peak intensity ratios (deuterated versus unlabeled).