HS-GC Determination of Trimethylamine in Exhaust Gas at Stationary Pollutive Sources

Trimethylamine (TMA) in exhaust gas at stationary pollutive sources were collected either by the method given in HJ/T 55 or GB/T 16157 with definite amount of 0.12 mol·L^-1 HCl solution as absorbent. An aliquot of 10.00 mL of the dil. HCl solution containing TMA was taken and transferred into the head-space flask of the GC instrument, and 3.2 g of NaCl and 1.0 g K₂SO₄ were added and 500 μL of NaOH (w, 50%) solution, together with 100 μL of aq. ammonia were added successively. The head-space flask was then sealed hermetically and the HS-sampling was carried out at 80℃ for 30 min. CP-Volamine quartz capillary chromatographic column was selected for quantitative separation of TMA and other 5 aliphatic amines added for testing. FID was adopted for detection of response signals. To test for detection limit of the proposed method with collection of TMA in exhaust gas by the methods given in HJ/T 55 and GB/T 16157, 20 L of TMA standard gas were collected by the 2 methods separately, and 7 sets of parallel determinations were performed by the GC analysis by taking 10.00 mL aliquots from the HCl solution absorbed with TMA. Detection limitt_(n-1,0.99)×s of 0.004 mg·m^-3 was found for collection of TMA by the method given in HJ/T 55, and detection limitt_(n-1,0.99)×s of 0.02 mg·m^-3 was found for collection of TMA by the method given in GB/T 16157. Standard TMA gas samples with 3 concentration levels of 0.510 μmol·mol^-1, 0.102 μmol·mol^-1 and 0.010 2 μmol·mol^-1 were collected and analyzed by thd given method for 6 parallel determinations, and values of recovery found were in the range of 90.1%-108%, and RSDs found were ranged from 2.2% to 6.7%. As shown by the results obtained by analyzing several substantial samples, the proposed method was feasible to be used in supervision and controlling the ejection of TMA in atmosphere, and was effective in meeting with the requirements given in the national standard GB 14554-93 and in local standards of Shanghai and Tianjin Muncipalities, pertaining regulations of ejection of stenchy pollutants.