Lumi-Phos 530 is a ready-to-use chemiluminescent reagent formulation containing the alkaline phosphatase (AP) substrate, Lumigen PPD. Lumi-Phos 530 is useful for chemiluminescent detection of AP conjugates in immunoassays and DNA probe assays. It provides ultrasensitive detection of analytes captured on magnetic particles and in microtiter plate wells. Lumi-Phos 530 is 10,000 times more sensitive than colorimetric substrates in solution.