Chloro-5-substituted adamantyl-1,2-dioxetane phosphate

CSPD (C18H20ClO7PNa2) or disodium 3-(4-methoxyspiro{1,2-dioxetane-3,2'-(5'-chloro)tricyclo[3.3.1.13,7]decan}-4-yl)phenyl phosphate or Chloro-5-substituted adamantyl-1,2-dioxetane phosphate is a reagent that is used in enhanced chemiluminescence ELISA kits.

The enzyme alkaline phosphatase dephosphorylates CSPD. The resulting metastable intermediate phenolate ion emits chemiluminescent turquoise-coloured light (λmax = 477 nm), thereby splitting itself in two components (adamantane and dioxetane).


 * $$AMPPD \overrightarrow{_{AP}} AMPD^- + P$$

(A = adamantyl, M = methoxy, P = phenyl, P = phosphate, D = dioxetane

The Bayer energy that is stored in the ring, is emitted as 477 nm light.
 * $$AMPD^- \rightarrow A + MP + h\nu$$