Selectivity chemical, chemiluminescence

M21. McCapra, F., and Beheshti, I., Selected chemical reactions that produce light. In Bioluminescence and Chemiluminescence Instruments and Applications (K. Van Dyke, ed.), Vol. 1, pp. 9-42. CRC Press, Boca Raton, FL, 1985. 

Unlike photoluminescent techniques, where some degree of selectivity is often derived from the intrinsic excitation and emission wavelengths of the analyte, the inherent selectivity of chemiluminescence detection arises from the limited number of chemical reactions that produce significant amounts of light. Furthermore, wavelength discrimination usually offers no advantage to the chemiluminescence detection, as different analytes often lead to the same emitting species, and should be avoided due to the detrimental effect on sensitivity. 

Selectivity of chemiluminescence reactions can be a concern. Some reactions are essentially compound-specific. An example is tetrakis(dime-thylamino)ethylene, which undergoes chemiluminescence reaction only with Oz- Although such specificity provides freedom from measurement interference, that chemiluminescence reaction then lacks universal application. In other cases, several species could yield emission with a given reagent. These situations then require coupling of the chemiluminescence detection with some sort of highly selective physical or chemical step (such as chromatography, immunoassay, enzyme reactions) to achieve an interference-free measurement. An... 

Nowadays all over the world considerable attention is focused on development of chemical sensors for the detection of various organic compounds in solutions and gas phase. One of the possible sensor types for organic compounds in solutions detection is optochemotronic sensor - device of liquid-phase optoelectronics that utilize effect of electrogenerated chemiluminescence. In order to enhance selectivity and broaden the range of detected substances the modification of working electrode of optochemotronic cell with organic films is used. Composition and deposition technique of modifying films considerably influence on electrochemical and physical processes in the sensor. 

The 02, radical can act as an oxidant as well as a reductant and chemical estimates of its production can also be based on its ability to oxidize epinephrine to adren-ochrome [62], These chemical methods have the additional advantage of not requiring highly specialized equipments. Also based on its redox property, the 02 radical can be determined by chemiluminescence methods through the measurement of the intensity of the fluorescence radiation emitted after chemical oxidation of 02 by, e.g., lucigenin [63-67], These methods, however, are limited by the poor selectivity and lack of capability for in-vivo performance. 

This review deals mainly with BL analytical applications in the last 10-15 past years, but some previous fundamental works are also listed. In Table 3 some fundamentals references of general interest and the findings of recent symposia on this topic are collected. In the journal Luminescence, the Journal of Biological and Chemical Luminescence (previously Journal of Bioluminescence and Chemiluminescence) are also reported surveys of the recent literature on selected topics (like ATP or GFP applications), instruments, and kits commercially available. 

Figure 10 Chemiluminescence spectrum of S2 observed in the selective reaction of OCIO with H2S. Note that this is the same excited-state species observed by the FPD. (Reprinted with permission from Ref. 81. Copyright 1982 American Chemical Society.)...

Gas chromatography is one of the most powerful analytical techniques available for chemical analysis. Commercially available chemiluminescence detectors for GC include the FPD, the SCD, the thermal energy analysis (TEA) detector, and nitrogen-selective detectors. Highly sensitive detectors based on chemiluminescent reactions with F2 and active nitrogen also have been developed. 

The most commonly used and widely marketed GC detector based on chemiluminescence is the FPD [82], This detector differs from other gas-phase chemiluminescence techniques described below in that it detects chemiluminescence occurring in a flame, rather than cold chemiluminescence. The high temperatures of the flame promote chemical reactions that form key reaction intermediates and may provide additional thermal excitation of the emitting species. Flame emissions may be used to selectively detect compounds containing sulfur, nitrogen, phosphorus, boron, antimony, and arsenic, and even halogens under special reaction conditions [83, 84], but commercial detectors normally are configured only for sulfur and phosphorus detection [85-87], In the FPD, the GC column extends... 

The NO + 03 chemiluminescent reaction [Reactions (1-3)] is utilized in two commercially available GC detectors, the TEA detector, manufactured by Thermal Electric Corporation (Saddle Brook, NJ), and two nitrogen-selective detectors, manufactured by Thermal Electric Corporation and Antek Instruments, respectively. The TEA detector provides a highly sensitive and selective means of analyzing samples for A-nitrosamines, many of which are known carcinogens. These compounds can be found in such diverse matrices as foods, cosmetics, tobacco products, and environmental samples of soil and water. The TEA detector can also be used to quantify nitroaromatics. This class of compounds includes many explosives and various reactive intermediates used in the chemical industry [121]. Several nitroaromatics are known carcinogens, and are found as environmental contaminants. They have been repeatedly identified in organic aerosol particles, formed from the reaction of polycyclic aromatic hydrocarbons with atmospheric nitric acid at the particle surface [122-124], The TEA detector is extremely selective, which aids analyses in complex matrices, but also severely limits the number of potential applications for the detector [125-127],... 

The chemical characterization of aerosol particles currently is of great interest in the field of atmospheric chemistry. A major goal is the development of a method for continuous elemental analysis of aerosols, especially for the elements C, N, and S. Chemiluminescence reactions described in this chapter have adequate sensitivity and selectivity for such analyses. In fact, considering that a 1- j.m-diameter particle has a mass of =0.5-1.0 pg, online analysis of single aerosol particles should be achievable, especially for larger particles. 

The acridinium ester (AE) in an AE-labeled cDNA probe hybridized to target DNA is less likely to be hydrolyzed than in the unhybridized conformation (Fig. 10) [9-11]. Single-base mismatches in the duplex adjacent to the site of AE attachment disrupt this protection, resulting in rapid AE hydrolysis [11]. Hydrolysis by a weak base renders AE permanently nonchemiluminescent. After hydrolysis, it is possible to use the remaining chemiluminescence as a direct measure of the amount of hybrid present. This selective degradation process is a highly specific chemical hydrolysis reaction, which is sensitive to the local environment of the acridinium ester. The matched duplex can be detected and quantified readily, whereas the mismatched duplex produces a minimal signal. 

Application of chemiluminescence to chemical analysis has been developing since the latter half of the 1950s. This method has many advantages, e.g., high sensitivity, good selectivity, linearity in a wide concentration range, and quick response. It has also been used for the measurement of air pollutants. This method, however, requires a supply of reactants to produce luminescent species through chemical reaction. This is a difficult point for the application of this method to gas sensors. 

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