Thomas G. Chasteen
Department of Chemistry
Sam Houston State University
Huntsville Texas 77341-2117 U.S.A
Chemiluminescence as an analytical tool has three important strengths:
* (and often) a wide linear range
The first often means lower detection limits for chemiluminescence when compared to
absorption or fluorescence techniques in pursuit of the same analyte. The second,
selectivity, is derived from the fact that the analyte of interest generates its signal
often in the presence of normally interfering compounds that, in this case, do not
themselves produce light when the chemiluminescent reagents are mixed together. And the
third is analytically useful because samples of larger concentration ranges can be
analyzed without dilution. This advantage is derived from the way that chemiluminescent
light is generated and measured: using no source lamp for light production and a
phototransducer with an inherent wide range of response for light detection.
The analytical chemiluminescent signal is produced by a chemical reaction (or
reactions) and requires no light source for excitation (as in the more common fluorescence
and phosphorescence). Its emission appears out of an essentially black background, and
therefore the only background signal is that of the photomultiplier tube's
(phototranducer's) dark current. Subsequently, light source and detector warm-up and drift
and the interference from light scattering present in absorption and fluorescence methods
Although the above is true, chemiluminescence is still not as widely applicable as
absorption, emission, or even fluorescence methods of detection because so few molecules
undergo native chemiluminescence with common reagents. That problem is often solved by
derivatizing analytes with chemiluminescent tags.
Online papers which utilized chemiluminescence can be seen at this site in the
http://www.photobiology.com/v1/default.htm First Internet Conference on Photochemistry and
The following is a brief primer on common chemiluminescence reagents:
|Lophine (chemiluminescence discovered in the last
quarter of the nineteenth century)
|Luminol (or its derivatives)
|Lucigenin (or its derivatives)
H2O2 or organic peroxides are commonly used as the oxidants in
the solution phase chemiluminescent techniques. There are many ways to generate these
oxidants or inhibit their generation or catalyze or suppress their action. Also there are
a variety of ways to tag otherwise chemiluminescence-less analytes with many of the first
set of reagents in the list above. Therefore, solution phase techniques are more common
that gas phase analytical gas phase methods. Ergo, HPLC and capillary electrophoresis (and
the many associated techniques) are finding wide applicability in this field.
Gas phase chemiluminescence methods have been used with gas chromatography,
supercritical fluid chromatography, and many nonchromatographic gas phase detectors in
which fast response is required.
A very few analytes of the hundreds or thousands that have been determined with
chemiluminescence methods include oxides of nitrogen (NOx), ozone, and hydrogen peroxide
in the atmosphere, DNA detection and sequencing, nucleic acids, alkaline phosphatase, and
antioxidants in kidney, brain, and plasma. Chemiluminescence has also been used as a probe
to determine susceptibility to cancer.
Finally, our http://www.shsu.edu/~chm_tgc/publications/pub.html
own work has yielded sensitive time course determinations of organo-sulfur, -selenium,
-tellurium, and -antimony metabolites in microbial cultures amended with toxic salts of
these elements using fluorine-induced chemiluminescence.
And, finally, of course, an excellent reference in this field is the http://journals.wiley.com/wilcat-bin/ops/ID0938013/0884-3996/prod
Journal of Bioluminescence and Chemiluminescence (John Wiley and Sons).