Detection, chemiluminescent metal catalyzed

The use of chemiluminescence reactions for the detection of metal ions by liquid chromatography was recently reported [59,60]. The detectors made use of the chemiluminescence produced in the reaction between luminol and hydrogen peroxide which is catalyzed by transition metals. The column effluent was mixed with the reagents in order to yield the chemiluminescence. The reaction was fast and was carried out at room temperature. By varying the pH of the buffer, selectivity towards certain metals was also achieved. For example, at pH 10-11 nickel could be analyzed but lead and aluminium were inactive at pH 13-14, the converse was true [59]. Aminco-Bowman has marketed a liquid chromatographic system in which amino acids and amines are analyzed by means of the fluorescence produced on reaction with the reagent fluorescamine. Fluorescamine does not fluoresce, but it does react with primary amino groups to produce fluorescent derivatives. The reaction is instantaneous and may be carried out at room temperature, usually at pH 9. This detection system promises to be far more sensitive than the ninhydrin detection system and is much more easily adapted to HPLC. 

Other detection methods have been used in optical MIP sensing systems. An MIP-based chemiluminescent flow-through sensor was developed for the detection of 1,10-phenanthroline (Lin and Yamada 2001). A metal complex was used to catalyze the decomposition of hydrogen peroxide and form the superoxide radical ion that can... 

The analytical applications of chemiluminescence fall into three broad categories. First, there are some chemiluminescent reactions that are catalyzed by specific compounds and that can, therefore, be diagnostic for the presence or quantitation of those compounds. For example, the hydrogen peroxide oxidation of the cyclic luminescent hydrazide luminol is catalyzed by transition metal ions such as Co(II), which can thereby be detected at a 10 pM concentration in a flow injection system (B33) and even down to 1 pM when the chemiluminescence is induced ultrasonically (K19). Other transition metal ions that have been similarly detected (in the 1-10 nM range) are Cr(III) (C13), Cu(II), and Ni(II) (S26). Other... 

Horseradish peroxidase (HRP) is also used for the detection of toxic compounds. A chemiluminescence test based on the reaction of luminol and an oxidant in the presence of the enzyme HRP has been developed to indicate the presence of toxins in a sample. The HRP-catalyzed reaction produces light that is measured by a lumi-nometer or a luminescence transducer. This enzyme has been used to detect a range of compounds such as phenols, amines, heavy metals, or compounds that interact with the enzyme, reduce light output, and indicate contamination. Test kits such as the Eclox Water Test Kit (Seven Trent Services, U.K.) is based on the use of HRP in the test format described earlier. This type of test is designed for the qualitative assessment of water samples for a range to compounds that inhibit the HRP activity. 

Chemiluminescence reactions Chemiluminescence reactions are usually redox reactions. The catalytic effect is reflected in the release of radiant energy. The best known of this type of reaction is the oxidation of luminol (5-amino-2,3-dihydrophthalazine-l,4-dione) by hydrogen peroxide, catalyzed by metal ions such as cobalt(II), copper(II), iron(II), nickel(II), chromi-um(III), and manganese(II) at pH 10-11. Detection limits of 10 to 10 mol 1 are readily achieved this way. Luminol is converted into a doubly charged anion that is subsequently oxidized to an excited singlet state that emits radiation on decomposing to... 

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