Solid-state peroxyoxalate chemiluminescence detection of hydrogen peroxide generated in a post-column reaction

Abstract

Solid-state chemiluminescence detection was used for the first time in conjunction with high-performance liquid chromatography (HPLC) and compared with liquid-phase chemiluminescence detection. The separation and detection of quinones commonly used in the wood pulping industry served as a model system. Hydrogen peroxide was produced by the eluting quinones in a post-column photochemical reaction. The reaction is photocatalytic in that up to 100 H 2O 2 molecules are produced for each analyte molecule. The H 2O 2 was subsequently detected using peroxyoxalate energy transfer chemiluminescence. The two additional reagents, a suitable fluorophor and an oxalate ester, may be introduced by means of post-column reagent pumps. It is shown that one pump may be eliminated by chemically bonding the fluorophor, 3-aminofluoranthene in these experiments, to glass beads or silica gel at a small cost in sensitivity and peak width. Use of an oxalate ester (bis-2,4,6-trichlorophenyl oxalate) in the solid state allowed the elimination of the remaining post-column pump at an additional cost in sensitivity and resolution. In this ultra-simple solid-state system using no post-column reagent pumps, detection limits were typically less than 5 pmol on-column, or about five times poorer than the best results obtained with a three-pump liquid phase system. The role of base catalysis of the chemiluminescence was also explored. As shown earlier for flow injection analysis, although addition of a catalyst enhances the detection sensitivity, the signal-to-noise ratio is only slightly improved; however, the catalyst does improve the precision and, as a buffer, reduces the susceptibility of the technique to interference from pH changes.