Chemiluminescence technique advantages

Kohler et al. discussed the potential of the chemiluminescence technique as an industrial test method. Imaging chemiluminescence was used to assess antioxidant performance. An advantage over oven aging was found to be the possibility for evaluation of the oxidative stability of samples with unusual geometries, such as fibres and powder particles [136]. A correlation was also found between oven aging and chemiluminescence measurements on stabilised PP and it was shown that chemiluminescence measurements done at... 

Derivatization reactions can be performed either pre- or postcolumn. As outlined by Brinkman, there are important advantages to using the postcolumn techniques whenever possible (68). First, the analytes can be separated in their original form, which often permits the adoption of published separation procedures. Second, artifact formation is generally not a serious problem, in contrast to precolumn derivatization, where it increases the separation difficulty and causes problems with quantitation. Third, the reaction does not need to be complete and the reaction products need not be stable the only requirement is reproducibility. Several reaction principles have been extensively applied. These include true chemical derivatization such as with dansyl chloride or o-phthalaldehyde UV irradiation, which can convert the analyte of interest into a more easily detectable species solid-phase reactions, including catalytic reactions such as with the use of immobilized enzymes and chemiluminescence techniques. 

The chemical laser technique resembles chemiluminescence, but stimulated, rather than spontaneous emission, is observed. One advantage, relative to the chemiluminescence technique, is that the vibrational population for the r = 0 level can be measured. However, unlike the chemiluminescence experiments most laser experiments are done in the 10-100 torr pressure range hence, the initial rotational populations are not measured and in fact rotational equilibration with the bath gas is assumed in obtaining relative vibrational populations. The chemical laser techniques have been recently reviewed, and, further details are not given here. 

Environmental monitoring has also taken advantage of acoustic levitation for the investigation of physico-chemical processes relevant to the troposphere — mainly at temperatures below 0°C. Gas-liquid transfer of H2O2 from the gas phase to the levitated droplet was studied from in situ chemiluminescence measurements. Also, freezing of stably positioned droplets was observed by means of a microscope and a video camera, and the usefulness of this technique for simulation and investigation of cloud processes thus demonstrated. Ex situ microanalysis of sub-microlitre droplets by the use of an optical fibre luminometer also proved an effective means for investigating important physicochemical processes at the micro scale [100]. 

In situations where a lower detection fimit is required and highly specific antisera are not available, cortisol is first extracted from serum before measurement. The extraction is performed in a manner similar to that for urine specimen extractions (see discussion later in this chapter). An important advantage of the direct assays is their superior precision compared with assays involving extraction. In part this may reflect the variability inherent in manual extraction techniques. In general, however, with the high specificity of the antibodies available today and with the use of very sensitive nonisotopic techniques, such as chemiluminescence and fluorescence, the quantitative measurement of cortisol in blood and urine is now relatively straightforward. 

The chemiluminescence apparatus and method described provide a sensitive technique for thermal oxidative stability evaluation of materials with many important advantages ... 

Because sensitivity is the principal advantage of IA, optimization of assay sensitivity is paramount. Fundamental requirements to optimize assay sensitivity are assay protocol design and reagent concentrations. Computer optimization techniques to improve sensitivity have been reported (13-16). Because of the complexity and variability of assay protocols, empirical approaches are more widely practiced. Ekins compared the sensitivities achieved by different method designs (17,18). Advances in chemiluminescent and time-resolved fluorescent labels enables IA sensitivity to reach attamole levels (18-20). 

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