Air quality - Determination of trimethylamine - Gas chromatography
1 Application scope
1.1 This standard is applicable to the determination of trimethylamine in the exhaust of malodorous pollution sources and the ambient air at the factory boundary. If the sample volume is 10 L, the lowest detection concentration is 2.5×10-3 mg/m3.
1.2 This standard determines trimethylamine in gaseous state.
1.3 Ammonia, methylamine, ethylamine, dimethylamine and other amine compounds in the samples do not interfere with the determination of trimethylamine under the chromatographic conditions selected by this method.
2 Principle
Glass microspheres coated with oxalic acid are used as adsorbents, and packed in the sampling tube to collect trimethylamine in the exhaust of malodorous pollution sources and the ambient air at the factory boundary. By injecting saturated potassium hydroxide solution and nitrogen into the sampling tube, the collected trimethylamine dissociated into a gaseous state is allowed to enter into a 100 mL desorption bottle subjected to vacuum treatment. The gas in the bottle is directly injected into a gas chromatograph with 1~2 mL, and the trimethylamine is quantitatively analyzed according to its chromatographic peak area (or peak height).
3 Reagents and materials
3.1 Reagents and materials for preparing sampling tubes
3.1.1 Glass microspheres: using glass microspheres as membrane carrier for chromatography, 60~80 mesh.
3.1.2 Oxalic acid: analytical grade.
3.1.3 Sampling tube: the piston of 1 mL syringe is removed, and the rear and front parts of the syringe are sealed with silicone rubber stoppers and plastic caps respectively.
3.1.4 Glass wool
3.1.5 Acetone: analytical grade.
