Carcinogenic compound, detector

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],... 

Based on animal studies, A-nitrosamines are compounds with proven carcinogenic effect. The search for sources and reduction of human exposure to their action is now one of the most important research problems. Currently, a major problem is the presence of A-nitrosamines and their precursors in food. Determination of A-nitrosamines in food relies on isolating these compounds by vacuum distillation in a basic medium, in the presence of liquid paraffin, followed by extraction with dichloromethane, pre-concentration of the sample, and analysis using GC. A thermal energy analyzer coupled to a gas chromatograph can serve as an efficient detector for these compounds. 

Figure 11.12 Comparison, following a chromatographic separation, of UV and fluorescence detection. Aflatoxins, which are carcinogenic contaminants present in certain hatches of grain cereals, are the subject of analysis by HPLC. Detection by fluorescence is much more sensitive to Gj and B2 than with UV detection (reproduced courtesy of SUPELCO). Below left, schematic of the different components of a LC-detector based upon fluorescence. This detector is able to find rapidely, for each compound eluted, the best coupling of excitation/emission without interrupting the chromatography underway (reproduced courtesy of a document from Agilent Technologies).

This type of detector is used for the detection and determination of very small quantities of substances with high electron affinities. In the trace range, the ECD is employed amongst other things for the analysis of traces of pesticides, nitro compounds, ozonides, chemical poison gases, pharmaceuticals, carcinogens, metabolites and metallo-organic compounds. 

Photometric detectors with variable wavelength capability are most widely used currently in LC. As an example, the carcinogenic aflatoxins in cereal products absorb light strongly at both 254 and 365 nm. Many other compounds also absorb light in the former wavelength. At 365 nm. 

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