text: ECL proved to be very useful in analytical applications as a highly sensitive and selective method. It combines analytical advantages of chemiluminescent analysis (absence of background optical signal) with ease of reaction control by applying electrode potential. As an analytical technique it presents outstanding advantages over other common analytical methods due to its versatility, simplified optical setup compared with photoluminescence (PL), and good temporal and spatial control compared with chemiluminescence (CL). Enhanced selectivity of ECL analysis is reached by variation of electrode potential thus controlling species that are oxidized/reduced at the electrode and take part in ECL reaction (see electrochemical analysis).
  It generally uses Ruthenium complexes, especially [[tris(bipyridine)ruthenium(II) chloride|[Ru(bpy)]]] (bpy = 2,2'-bipyridine) which releases a photon at ~620 nm regenerating with TPrA (Tripropylamine) in liquid phase or liquid–solid interface. It can be used as monolayer immobilized on an electrode surface (made e.g. of nafion, or special  thin films made by Langmuir–Blogett technique or self-assembly technique) or as a coreactant or more commonly as a tag and used in HPLC, Ru tagged antibody based immunoassays, Ru Tagged DNA probes for PCR etc., NADH or HO generation based biosensors, oxalate and organic amine detection and many other applications and can be detected from picomolar sensitivity to dynamic range of more than six orders of magnitude. Photon detection is done  with photomultiplier tubes (PMT) or silicon photodiode or gold coated fiber-optic sensors. The importance of ECL techniques detection for bio-related applications has been well established. ECL is heavily used commercially for many clinical lab applications.