Potential of chemiluminescence and bioluminescence in organic analysis

The possibilities offered by chemiluminescence (CL)-based analytical techniques apparently still remain unfamiliar to the average analytical researcher. Some of the advantages are that only minimal analytical instrumentation is required and because no external light source is needed, the optical system is quite simple. Hence strong background light levels are excluded leading to improved detection limits by this so-called "dark-field technique". CL is observed in solid-, gas- and liquid-phase reactions and all have been used analytically. In solution, the most frequently used systems involve the organic reagents: luminol and its derivatives, acridinium esters, lophine, peroxyoxalates, etc. Many important applications have been established in recent years for the determination of organic compounds, biomolecules, drugs and carcinogenics in a variety of environmental and clinical matrices. As in fluorescence detection, by applying derivatization techniques it is possible to convert a molecule, which does not possess the ability to participate in a CL system, into another specie featuring this property. The rapid development of immobilization techniques has considerably enhanced the applications of CL, especially in flow injection analysis (FIA), in immunoassay and in the development of CL-based sensors. Also, the combination of CL-based detection employing prior separation methodologies such as high performance liquid chromatography (HPLC) or capillary electrophoresis (CE) has proved to offer promising analytical possibilities, providing excellent analytical sensitivity and selectivity, and allowing the resolution and quantification of various analytes in a complex mixture. This review intends to show general principles and characteristics of the technique which make it very useful in organic analysis.