Collection and ion chromatographic determination of ammonia and methylamines in air

A method is described for the collection of ammonia (NH3), monomethylamine (MMA), dimethylamine (DMA), and trimethylamine (TMA) from air and their subsequent determination by ion chromatography. Samples are collected with 800-mg silica gel sampling tubes at a flow rate of 1 L/min for 10 minutes or at 100 mL/min for up to 7.5 hours. Samples collected with sulfuric acid-treated tubes can be stored at room temperature for at least 21 days with no loss in recovery. Untreated samples can be stored in a refrigerator up to 32 days. The method has been validated from 2 to 50 ppm v/v when a 10 L air sample is taken. No loss in recovery was observed when sampling up to 23 L of air at 100% relative humidity. The recovery and total precision (95% confidence level) for NH3, MMA, DMA, and TMA were 91 +/- 12.5%, 93 +/- 10.3%, 92 +/- 9.6% and 84 +/- 17.6%, respectively.