The PGD1 Quant-PAK has been designed for the convenient, precise quantification of PGD1 by GC- or LC-MS. It includes a 50 μg vial of PGD1-d4 and a precisely weighed vial of unlabeled PGD1, with the precise weight indicated on the vial. This unlabeled PGD1 can be used to quantify the PGD1-d4 standard by constructing a standard curve of peak intensity ratios (deuterated versus unlabeled).