Methods used for the analysis of N-nitrosodi-n-propylamine in biological samples are shown in Table 6-l. The use of vacuum distillation at low temperature (60-70°C) and trapping the distillate in dry ice/acetone bath is the preferred method for the isolation of the compound from biological matrices. Because of its selectivity and sensitivity, methods using Thermal Energy Analyzer (TEA) detectors are selected for quantification of this compound. In cases where analysis of multiple pollutants are necessary, mass spectrometric detectors, in spite of their lower sensitivity for nitrosodi-n-propylamine, may be favored over the TEA detector.
Methods used for the analysis of N-nitrosodi-n-propylamine in environmental samples are given in Table 6-2. Two pretreatment methods are most suitable for the analysis of this compound in environmental samples. When the matrix is not too complex, as in the case of drinking water, surface water, groundwater and wastewater, solvent extraction is the preferred method. With more complex matrices as soil and foodstuffs, vacuum distillation and cold trapping is more suitable. The three methods commonly used for the quantification of this compound in environmental samples are mass spectrometry, nitrogen-phosphorus detectors (NPD) and TEA in chemilumin escence mode. Each of these detectors has its own advantages and disadvantages. When a high sensitivity is required, a method using a TEA detector may be the method of choice. For multipollutant analysis in a single sample, mass spectrometry may be more suitable. Nitrogen-phosphorus detectors, on the other hand, may be more cost-effective and will provide reasonable specificity and sensitivity for nitroso compounds. A Hall detector in the pyrolytic mode may be preferable over NPD detectors because it may require less sample clean-up (Rhoades et al. 1980).