Kinetic analysis, chemiluminescence

Figure 10. Simulated decay curves from the kinetic analysis of the TCPO-H2O2-DPA chemiluminescence. Arbitrary units (a.u.) used on both axes. (Reproduced from Ref. 24. Copyright 1986 American Chemical Society.)...

Comparison of chemiluminescence isothermal runs with oxygen uptake and DSC measurements has been at the centre of interest since practical industrial applications of the chemiluminescence method were attempted. It is a fact that the best comparison may be achieved when studying polymers that give a distinct induction time of oxidation typical for autoaccelerating curves of a stepwise developing oxidation. This is the particular case of polyolefins, polydienes and polyamides. The theoretical justification for the search of a mutual relationship between the oxidation runs found by the various methods follows directly from the kinetic analysis of the Bolland-Gee scheme of polymer oxidation. 

From this detailed kinetic analysis of the complex pH dependence for the chemiluminescence intensity we conclude that only the enzymatic dephosphorylation of AMPPD... 

A kinetic analysis of the results, based on (17) and its O+OH analog, is in satisfactory agreement with observations on a wide variety of flames. These flames are relatively cool, and the concentrations of H and OH exceed their equilibrium values even in the burned gases, so that the observed sodium emission is definitely chemiluminescent. The third order rate coefficients for excitation by H+H and H+OH are estimated to be 8 x 109 and 2x 1010 l2.mole-2.sec-1, corresponding to an efficiency near unity per triple collision. The possible importance of mechanisms of the type (14,15) has not been carefully studied. 

Kinetic analysis of luminol-dependent chemiluminescence demonstrated that a solution of berbamine (20 pM) was found to inhibit the generation of various types of reactive oxygens by guinea-pig neutrophils. The results of these and other experiments suggest that berbamine inhibits the active oxygen generation via the stabilization of plasma membrane and the inhibition of phospholipid-dependent protein kinase (PKC) and NADPH oxidase activation [178]. 

Methods in which some property related to substrate concentration (such as absorbance, fluorescence, chemiluminescence, etc.) is measured at two fixed times during the course of the reaction are known as two-point kinetic methods. They are theoreticahy the most accurate for the enzymatic determination of substrates. However, these methods are technically more demanding than equifibrium methods and all the factors that affect reaction rate, such as pH, temperature, and amount of enzyme, must be kept constant from one assay to the next, as must the timing of the two measurements. These conditions can readily be achieved in automatic analyzers. A reference solution of the analyte (substrate) must be used for calibration. To ensure first-order reaction conditions, the substrate concentration must be low compared to the K, (i.e., in the order of less than 0.2 X K, . Enzymes with high K , values are therefore preferred for kinetic analysis to give a wider usable range of substrate concentration. 

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. 

In analogy with chemiluminescence (Chp. 1.4.4) various ICL experiments may be carried out in inert or oxidising atmosphere. ICL in inert atmosphere may be acquired isothermally or by linear heating. The latter approach is less satisfactory for kinetic analysis, because data are not isothermal and sample melting may cause changes in the geometric parameter G of eq. (1.12). To serve as an analytical tool... 

The verification of theoretical data obtained by simulation of peroxide oxidation kinetics of macromolecules with experimental data, obtained from chemiluminescent analysis of blood using automated complex ChLC-1. This automated complex was developed by the authors and laboratory colleagues. 

Anions of another group were derivatized with formation of gaseous chemiluminescing species. Chemical reaction - gas extraction has been used with chemiluminescence detection in the stream of canier gas in on-line mode. Rate of a number of reactions has been studied as well as kinetic curves of extraction of gaseous products. Highly sensitive and rapid hybrid procedures have been developed for the determination of lO, BrO, CIO, CIO, NO,, N03, CrO, CIO, Br, T, S, 803 with detection limits at the level of pg/L, duration of analysis 3 min. 

Instrumental methods of peroxide analysis feature polarography, which is used to detn hydroperoxides, peroxyesters and diacyl peroxides as well as dicyclohexyl peroxydicarbonate in polystyrene. Other techniques include infrared (800 to 900cm 1) chemiluminescent analysis for kinetic studies, and chromatography for the identification and separation of peroxides in complex mixts (Refs 5,6, 7,14,15,16,17, 20 21)... 

Surprisingly, despite requiring two analyte molecules to produce one S2 molecule, the kinetics of the chemiluminescent reaction are first order with respect to the sulfur compound. This can be explained if every H2S or CH3SH molecule is consumed in the reaction and every S atom recombines to form S2, through the use of an excess of OCIO to maintain pseudo-first-order reaction conditions [81]. The limit of detection for this analysis was found to be 3 ppbv for H2S. 

Allen, R. C. (1986). Phagocytic leukocyte oxygenation activities and chemiluminescence A kinetic approach to analysis. Methods Enzymol. 133 B, 449-93. 

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