Hag. Niederlander et al., CHEMILUMINESCENCE DETECTION IN LIQUID-CHROMATOGRAPHY BASED ON PHOTOOXYGENATION INVOLVING REACTIVE OXYGEN INTERMEDIATES, Analytica chimica acta, 285(1-2), 1994, pp. 143-159
A luminol chemiluminescence (CL) detection system for reversed-phase l
iquid chromatography (RPLC), based on on-line photochemical production
of organic hydroperoxides is presented. Tetramethylethylene (TME) was
used as a reagent for generation of hydroperoxides in a post-column p
hotochemical reactor, which is based on photo-oxygenation induced by t
he analytes eluting from the column. In the detector cell CL is genera
ted by the microperoxidase (MP-11) catalyzed reaction of the photochem
ically produced hydroperoxides and luminol. The experimental parameter
s were optimized considering the photochemical reactor and the chemilu
minescence detector independently. Optimization of the parameters was
directed towards detection of analytes in a gradient reversed-phase ch
romatographic system and thus restricted by the eluent composition use
d for separation. The solvent composition was not varied freely; in or
der to achieve compatibility of the (new) detection system and (gradie
nt) RPLC, it is largely determinated by the eluent required to perform
the chromatographic separations. The applicability of the optimized s
ystem was evaluated for some model analytes and comparisons were made
to the CL detection system based on photochemical generation of dioxet
anes and to UV-visible absorption detection. Mechanistic implications
with respect to the photo-induced production of hydroperoxides in the
photochemical reactor were considered and the influences of some known
singlet oxygen quenchers and radical chain inhibitors on the signal w
ere measured. The detection system was applied to the detection of pol
ar pollutants in a gradient reversed-phase chromatographic system, ana
lyzing spiked academic solutions and tap-water samples, in the latter
case combined with on-line trace enrichment techniques.