Chemiluminescence CL Detector

CL detection is based on the optical emission of an excited species formed in a chemical reaction. For instance, an excited species is formed when luminol (or 3-aminophthalhydrazide) reacted with H202 as catalyzed by various substances, such as metal ions or the peroxidase enzyme. CL detection is achieved as in fluorescent detection, except that no excitation light is needed. 

CL detection has been employed in various chemical analyses. For instance, determination of mouse IgG was based on the CL reaction of an HRP-goat antimouse IgG (HRP-Ab) and the luminol/H202 system. The amount of HRP-Ab decreased with an increasing amount of mouse IgG (10-60 ig/mL). Mouse IgG was then quantified using an internal standard (microperoxidase) after CZE separation. To enhance light collection in CL detection, an aluminum mirror was deposited on the back side of the microchip [720], 

Determination of metal ions (Cr3+, Co2+, Cu2+) has been achieved using the metal-catalyzed luminol-peroxide system. The EOF delivery of the CL reagent (H202 pH 11.7) in the aqueous system can be achieved using a side channel (with luminol present in the separation buffer with a pH of 6.0) [168]. 

In another report, CL determination of xanthine (1 mM) was achieved. Xanthine oxidase (XOD) first converted xanthine to H202 and uric acid. Then H202 reacted with the CL reagents, HRP and luminol, to produce the CL signal [721]. 

CL systems other than luminol have also been used, such as the Ru(bpy)2+ (or TBR) system. Chemical reaction of TBR has been achieved by oxidation using cerium(IV) sulfate [283,722] or lead oxide [722]. The addition of a nonionic surfactant (Triton X-45) strongly enhanced the CL emission [722]. The TBR system has been applied on a glass chip for the determination of alkaloids, such as codeine [722], or atropine and pethidine [283]. 

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