Determination of Tertiary Amines in Air

Abstract

Methods have been developed for air sampling of gaseous tertiary amines on solid sorbents. Sampling was performed at three different air levels and at 20 percent and 85 percent relative air humidity, respectively. Desorption was carried out by solvent extraction prior to high-resolution gas chromatographic analysis with flame ionization or nitrogen-phosphorus detection. Seven amines, differing in the length and shape of the carbon chains, were selected for the study and divided into three groups. The members of the first group, consisting of dimethylethylamine (DMEA), methyldiethylamine (MDEA), and triethylamine (TEA) were collected using charcoal tubes and desorbed with 5 percent ethanol in dichloromethane. The amine air levels were 1, 10, and 50 ppm. The recoveries of these amines were 92–100% (n = 6, RSD = 1–4%). Storage studies (5 days at room temperature followed by 9 days in a freezer) showed recoveries of 87 percent (DMEA), 89 percent (MDEA), and 82 percent (TEA). Determination of DMEA in an air sample from an iron foundry was also carried out.

The larger amines were studied at 0.5, 5, and 25 ppm air level. The members of the second group, consisting of ethylmorpholine (EM) and dimethylcyclohexylamine (DMCA), were collected on Amberlite XAD-2 and desorbed with ethyl acetate. The recoveries were 81–99 percent for EM (n = 6, RSD = 1–4%). The storage studies were performed in darkness at room temperature for 14 days. The recoveries were then 96 percent (EM) and 87 percent (DMCA).

The members of the third group, consisting of dimethyldodecylamine (DMDA) and dimethylhexadecylamine (DMHA), were collected on Amberlite XAD-7 and desorbed with 5 percent ethanol in ethyl acetate. The recoveries were 93–97 percent (n = 6, RSD = 2–6%). The recoveries were still > 94 percent for both amines after 14 days' storage in darkness at room temperature.