Detection compounds containing nitrogen

Figure 5.14. Detection of organic products oxygenates and organic nitrogen-containing compounds at the outlet of non-thermal plasma reactor without catalyst. Feed NO (500 ppm) - C3H6 (2000ppm Cj) - 02 (8 vol.%) - N2 [32],...

Where the target analyte contains heteroatoms such as nitrogen, phosphorus and sulfur, atom-selective detectors can provide an ideal detection method. A number of examples appear in the literature of the use of a detector called a thermal energy analyser (TEA) for the measurement of A-nitroso compounds [14-17] and aromatic nitro compounds [18]. This has also been used as an HPLC detector [19, 20], and a modified TEA has been reported to be useful for analysis of amines and other nitrogen-containing compounds [17]. Unfortunately, this technique appears not to have gained in popularity, since no reports have appeared in the literature for over two decades. 

At sufficiently high temperatures, the detector also responds to a variety of nitroaro-matics and to (V-nitrosodimethylamine. NOz yields of 0.70 and 0.90 were obtained for 2,4-DNT and TNT, respectively. The detection system exhibits a linear response for all nitrogen-containing compounds studied, and the detection limit for the determination of organic nitrates was found to be 0.05pmol. The relative response factors for aromatic nitro compounds and nitrosamine for the pyrolyser/luminol detector are presented in Table 3. 

Nitrogen-containing compounds with basic groups can successfully be trapped on silica. This implies for nitrogen mustards as well as for their precursors. As an example, triethanolamine (CAS CAS 102-71-6) was detected in air at low levels by trapping on activated silicagel (ORBO 53 tubes), desorbed and trimethylsilylated prior to GC/MS analysis. Using the SIM mode at mlz 262 ([M - CH2-0-TMS]+, a detection limit of l-2pg was reached for the method (38). 

Other detectors in use include the thermal conductivity detector (TCD) and the phosphorus-nitrogen detector (PND) which is much used in toxicology because of its selectivity for nitrogen-containing compounds. It is a feature of gas-liquid chromatography that spectrophotometric detectors can be coupled readily to the outflow for detection this includes IR, NMR and, particularly, mass spectrometers, in combined GC-MS analysers. Spectroscopic analysis allows structural information to be... 

In addition to the alkylbenzenes and the phenols indicated in Table 9.1.10, traces of a series of nitrogen containing compounds were detected in the pyrolysate. These compounds obviously have a different origin than the pyrolysate of pure polymer. The list of these compounds is given in Table 9.1.11. 

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