Chemiluminescent reaction types

The question is whether diazaquinones are in fact in the main stream 2> of cyclic diacyl hydrazide chemiluminescence or whether they are only one of the possible intermediates or, finally, whether diazaquinone chemiluminescence is a special type of chemiluminescence reaction although very closely related to the chemiluminescence of the corresponding hydrazides. E. H. White and D. F. Roswell 2> point out that the respective diazaquinone may actually be one of the possible intermediates formed either from the hydrazide dianion (essential in aprotic solvents) or from a hydrazide radical anion (which is the usual species in aqueous media). This is outlined in the following scheme ... 

If cl is the efficiency of the chemiluminescent reaction, which is the ratio of the number of photons emitted to the number of molecules of reactant reacting in toto, it can be defined for a type I reaction as... 

If the reactants in a type I chemiluminescence reaction are rapidly mixed they will result in an emission whose intensity Ia, can be measured as a function of time. A typical time intensity curve for a CL reaction is shown in Figure 2. 

In recent years different types of surfactants have been used, in concentrations above their cmc, forming normal micelles, to improve different aspects of chemiluminescent reactions. Though the choice of the best surfactant depends on the characteristics of the chemiluminescent reaction, the surfactants most used have been the cationic (fundamentally quaternary ammonium salts) and to a lesser degree the anionic, the nonionic, and the zwiterionic compounds. 

All integrated sensors based on an interaction between the analyte and reagent (neither of which is used in a retained form) and regeneration of the latter rely on chemiluminescent reactions involving electroregeneration of the reagent or a quenching phenomenon. On the other hand, absorptiometric and reflectometric sensors of this type use colorimetric acid-base indicators supported on a suitable material. 

Two particularly interesting chemiluminescent reactions have been discovered using beams of alkali dimer molecules (M2). These species are formed in high yield in an alkali metal nozzle beam source and they can be separated from the remaining atoms by means of an inhomogeneous magnetic field. This technique has made it possible to study reactions of these diatomic species by molecular beam methods for the first time [364] and as a result it has been demonstrated conclusively that reactions of the type... 

Chemiluminescence of uranium may be classified on two general types (a) uranyl ion accepts energy from the excited species formed in chemiluminescent reaction ... 

The proposed chemiluminescence detection method has proved to be simple, rapid and sensitive for CPLX determination. The results indicated that the proposed chemiluminescence reaction system is not only appropriate for batch type system analysis but it may also be convenient for flow injection system due to intense chemiluminescence signal. Utilizing the proposed method, the CPLX content of commercial tablets as well as in urine sample can be determined with reasonable selectivity. 

Before considering detector characteristics and some recent developments in chemiluminescence detection, it should be noted that analytical applications of chemiluminescence involve two types of chemiluminescent response. In the first type, the chemiluminescent molecule is used as a detection label and is, therefore, present in limiting concentration relative to the reagents used to initiate the chemiluminescent reaction. The chemical reaction will therefore be pseudo first order. The slowest process in the sequence of events leading to light emission is the reaction itself, e.g., hydrolysis, bond-breaking, and rearrangements. From Eq. 

The third type of luminescence, chemiluminescence, is based on the emission of radiation by an excited species formed during a chemical reaction. In sonic instances. the excited species is the product ol a reaction belw-een the analyte and a suitable reagent (usually a strong oxidant such as ozone or hydrogen peroxide). The result is an emission spectrum characteristic of the oxidation product of the analyte or the reagent rather than the analyte itself. In other instances, the analyte is not directly involved in the chemiluminescence reaction. Instead, the analyte inhibits or has a cuialyiic effect on a chemiluminescence reaction. 

Kinetic analysis of chemiluminescent reactions of this type is usually directed towards the deduction of values for ki, k i, k, k and the rate constants of any other processes involved in formation or removal of XY. Since such studies are steady-state analyses, they do not utilize the time resolution associated with axial displacement along the flow system. 

The first type of enzyme application in microfluidics is chemical sensing. Sensors can be constmeted in cases where an enzyme turns over a particular smaU-molecule substrate to produce a product quantifiable by fluorescence, chemiluminescence, absorbance spectroscopy, or electrochemical detectors. In cases where the substrate is not detectable itself, an enzymatic product can often be coupled to another enzyme that produces a detectable product. For example, there are a wide variety of small molecules (such as nutrients, amino acids, and sugars) that can be coupled to the chemiluminescent reaction of luminol and peroxide in the presence of horseradish peroxidase. These enzyme-substrate assays were the first to be adapted to microfluidic devices — a great number of small-molecule sensors have been developed based on microfluidic channels with electroosmotic or hydrodynamic flow, and pre-loaded microfluidic cartridges containing nanoliter volumes of reagents have... 

Ruthenium complexes need a strong reductant or oxidant for chemiluminescent reactions of type (b) and (c) above. These reactive compounds are usually radicals derived from simple organic compounds such as amines, amino acids, the reduced form of )S-nicotinamide adenine dinucleotide (NADH), and some antibiotics. Analytical procedures have been developed for some of these compounds on this basis, e.g., for tripropylamine, which gives a detection limit of 2 X 10 moll. ... 

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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