Luminol hydrogen peroxide determination

Divalent copper, cobalt, nickel, and vanadyl ions promote chemiluminescence from the luminol—hydrogen peroxide reaction, which can be used to determine these metals to concentrations of 1—10 ppb (272,273). The light intensity is generally linear with metal concentration of 10 to 10 M range (272). Manganese(II) can also be determined when an amine is added to increase its reduction potential by stabili2ing Mn (ITT) (272). Since all of these ions are active, ion exchange must be used for deterrnination of a particular metal in mixtures (274). 

Luminol chemiluminescence has also been recommended for measuring bacteria populations (304,305). The luminol—hydrogen peroxide reaction is catalyzed by the iron porphyrins contained in bacteria, and the light intensity is proportional to the bacterial concentration. The method is rapid, especially compared to the two-day period required by the microbiological plate-count method, and it correlates weU with the latter when used to determine bacteria... 

Among the different synthetic compounds used for hydrogen peroxide determination, only luminol and oxalate esters have found widespread use and were really evaluated for H2O2 detection. 

The CL system luminol-hydrogen peroxide was characterized by Hoshino and Hinze in HTAC reversed micelles, formed in a 6 5 (v/v) chloroform-cyclohexane mixture [63], The results indicate that such a CL system can be used from an analytical point of view in a pH interval of 7.8-9.0 without the need to add a catalyst or a co-oxidant. In these conditions an analytical method was established for determination of hydrogen peroxide that, apart from supplying much milder conditions compared to the usual situation in an aqueous medium, is also acceptably precise and reproducible. 

As compounds exhibiting enhancing effects on CL reactions, a variety of phenols, e.g., firefly luciferin and 6-hydroxybenzothiazole derivatives [12,13], 4-iodophe-nol [14], 4-(4-hydroxyphenyl)thiazole [15], 2-(4,-hydroxy-3 -methoxy-benzyli-dene)-4-cyclopentene-l,3-dione (KIH-201) [16], and 2-(4-hydroxyphenyl)-4,5-diphenylimidazole (HDI) and 2-(4-hydroxyphenyl)-4,5-di(2-pyridyl)imidazole (HPI)[17] (Fig. 6A), and phenylboronic acid derivatives, e.g., 4-phenylylboronic acid [18], 4-iodophenylboronic acid [19], and4-[4,5-di(2-pyridyl)-l //-imidazol-2-yl]phenylboronic acid (DPPA) [20] (Fig. 6B), in the luminol/hydrogen peroxide/peroxidase system are well known. Rhodamine B and quinine are used as sensitizers in the CL-emitting reaction between cerium (IV) and thiol compounds. This CL reaction was successfully applied to the sensitive determination of various thiol drugs [21-32],... 

Ai -Aminooxymethylcarbonylhydrazino-D-biotin, DNA oxidative damage, 736, 634 3-Aminophthalate, luminol oxidation, 643, 644, 1239-41, 1244-6 7-Amino-4-trifluoromethylcoumarin, hydrogen peroxide determination, 649 Ammonium ion complex, mass spectrometry, 703, 704... 

Phthalein dyes, hydrogen peroxide determination, 628-9 Phthaloyl peroxide, luminol chemilumine scence, 1245 Physiological matrices... 

N,N, N, iV -Tetrakis(2-benzimidazolylmethyl)-l,3-diaminopropan-2-ol, hydrogen peroxide determination, 637 A,A,A, iV -Tetrakis[2 (l -ethylbenzimidazol-yl)-l, 3-diamino-2-hydroxypropane], transition metal peroxides, 1066 meiO-Tetrakis(4-sulfonatophenyl)porphine, luminol oxidation, 646... 

A method for the determination of vitamin BJ2 by means of the luminol-hydrogen peroxide system has been developed. The method depends on the release of bound cobalt in vitamin B12 by acidification of the vitamin. The cobalt so released is then permitted to quantitatively catalyze the oxidation of luminol by hydrogen peroxide. 

Du J, Li Y, Lu J. Flow injection chemiluminescence determination of thiamine based on its enhancing effect on the luminol-hydrogen peroxide system. Talanta 2002 57 661-5. 

Other chemiluminescence FIA methodologies for AA determination are based on AA acidic reduction of potassium dichromate to generate Cr(III) and subsequent luminol-hydrogen peroxide-Cr(III) chemiluminescence reaction [87,88], and on chemiluminescence reaction of AA with potassium permanganate in the presence of formaldehyde [89,90], formic acid [91], or CdTe nanocrystals [92] as sensitivity enhancers. Quinine is also used as an enhancer of chemiluminescence produced by reaction between AA and Ce(IV) in acid media [93]. Perez-Ruiz et al. [94] proposed a chemiluminescent reaction, in alkaline solution, of lucigenin with the products from the photooxidation of AA sensitized by toluidine blue. 

The great sensitivity of luminol to catalytic oxidation by transition metal ions has suggested a variety of analytical procedures. Although many reduceable metal ions cause light emission it is possible to exploit different valency states of the same metal, e.g. chromium since they often exert different catalytic effects on the luminol/hydrogen peroxide reactions, or alternatively one compound in a mixture of catalytically active metal ions can be specifically determined by appropriate complexation procedures [17]. 

Observations Table 2 shows the levels of free radicals determined by luminol chemiluminescence, H202 levels, and membrane lipid peroxidation determined by conjugated dienes. Total free radicals significantly increased by 1.4 fold, hydrogen peroxide significantly decreased 1.3 fold, and lipid peroxidation increased significantly 1.5 fold. 

The flow-cell design was introduced by Stieg and Nieman [166] in 1978 for analytical uses of CL. Burguera and Townshend [167] used the CL emission produced by the oxidation of alkylamines by benzoyl peroxide to determine aliphatic secondary and tertiary amines in chloroform or acetone. They tested various coiled flow cells for monitoring the CL emission produced by the cobalt-catalyzed oxidation of luminol by hydrogen peroxide and the fluorescein-sensitized oxidation of sulfide by sodium hypochlorite [168], Rule and Seitz [169] reported one of the first applications of flow injection analysis (FTA) in the CL detection of peroxide with luminol in the presence of a copper ion catalyst. They... 

The luminol reaction has been used for the determination of oxidizing agents such as hydrogen peroxide, for enzymes such as peroxidase and xanthine oxidase, and for metal ions such as copper or cobalt that catalyze this CL reaction [24],... 

The scope of CAR-CLS in analytical determinations has been expanded with one other type of CL reaction (luminol-based CL reactions are restricted to direct determinations of metal ions and some indirect ones). The so-called energy transfer CL is one interesting alternative, with a high analytical potential. As stated above, PO-CL systems based on the reaction between an oxalate ester and hydrogen peroxide in the presence of a suitable fluorophore (whether native or derivatized) and an alkaline catalyst are prominent examples of energy transfer CL. This technique has proved a powerful tool for the sensitive (and occasionally selective) determination of fluorophores its implementation via the CAR technique is discussed in detail later. 

Hydrogen peroxide produced as a result of reactions of oxidase enzymes with analyte substrates can be sensitively determined, both directly by luminol ECL and indirectly by Ru(bpy)32+ ECL. For the latter, hydrogen peroxide is detected on the basis of its ability to diminish the ECL reaction between Ru(bpy)32+ and added oxalate, by reacting with, and depleting the concentration of, oxalate. Thus ECL intensity is inversely proportional to the concentration of analyte. This principle has been used, for example, to determine cholesterol [70],... 

Other cationic surfactants such as TTAB, DTAB, DODAB, STAC, CEDAB, and DDDAB have been used in CL reactions with less frequency. Thus, tetradecyltrimethylammonium bromide [TTAB] has been used to increase the sensitivity of the method to determine Fe(II) and total Fe based on the catalytic action of Fe(II) in the oxidation of luminol with hydrogen peroxide in an alkaline medium [47], While other surfactants such as HTAB, hexadecylpiridinium bromide (HPB), Brij-35, and SDS do not enhance the CL intensity, TTAB shows a maximum enhancement at a concentration of 2.7 X 10 2 M (Fig. 11). At the same time it was found that the catalytic effect of Fe(II) is extremely efficient in the presence of citric acid. With regard to the mechanism of the reaction, it is thought that Fe(II) forms an anionic complex with citric acid, being later concentrated on the surface of the TTAB cationic micelle. The complex reacts with the hydrogen peroxide to form hydroxy radical or superoxide ion on the... 

Luminol derivatives produce emission of light by oxidation with oxygen and hydrogen peroxide under alkaline conditions. By utilizing this reaction, peroxides such as hydrogen peroxide and lipid hydroperoxides can be determined after HPLC separation. Metal ions [e.g., iron(II), cobalt(II), etc.] catalyzing the luminol CL reaction can also be determined. 

Some luminol derivatives have been developed as CL labeling reagents. Analytes prelabeled with luminol derivatives are separated by HPLC, mixed with postcolumn reagents such as hydrogen peroxide and an alkaline solution of potassium hexacyanoferrate (III), and then detected by a CL detector. Highly sensitive determination is possible by optimizing the conditions to increase the CL reaction efficiency for each analyte. 

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