Chemistry Department, Augsburg College, Minneapolis, Minnesota 55454, USA.
Environ Sci Technol. 2011 Oct 15;45(20):8881-8. doi: 10.1021/es201819a. Epub 2011 Sep 16.
An instrument to detect gaseous amines and ammonia is described, and representative data from an urban site and a laboratory setting are presented. The instrument, an Ambient pressure Proton transfer Mass Spectrometer (AmPMS), consists of a chemical ionization and drift region at atmospheric pressure coupled to a standard quadrupole mass spectrometer. Calibrations show that AmPMS sensitivity is good for amines, and AmPMS backgrounds were suitably determined by diverting sampled air through a catalytic converter. In urban air at a site in Atlanta, amines were detected at subpptv levels for methyl and dimethyl amine which were generally at a low abundance of <1 and ∼3 pptv, respectively. Trimethyl amine (or isomers) was on average about 4 pptv in the morning and increased to 15 pptv in the afternoon, while triethyl amine (or isomers or amides) increased to 25 pptv on average in the late afternoon. The background levels for the 4 and 5 carbon amines and ammonia were high, and data are very limited for these species. Improvements in detecting amines and ammonia from a smog chamber were evident due to improvements in AmPMS background determination; notably dimethyl amine and its OH oxidation products were followed along with impurity ammonia and other species. Future work will focus on accurate calibration standards and on improving the sample gas inlet.
描述了一种用于检测气态胺和氨的仪器，并呈现了来自城市现场和实验室环境的代表性数据。该仪器是一种常压质子转移质谱仪（AmPMS），由常压化学电离和漂移区与标准四极杆质谱仪耦合而成。校准表明，AmPMS 对胺具有良好的灵敏度，并且通过将采样空气分流通过催化转化器可以适当确定 AmPMS 的背景。在亚特兰大一个地点的城市空气中，亚 pptv 水平下检测到了甲基和二甲基胺，它们的丰度通常<1 和∼3 pptv 左右。三甲胺（或异构体）在早晨平均约为 4 pptv，并在下午增加到 15 pptv，而三乙胺（或异构体或酰胺）在下午晚些时候平均增加到 25 pptv。4 和 5 个碳胺和氨的背景水平很高，这些物质的数据非常有限。由于改进了 AmPMS 背景测定，从烟雾箱中检测胺和氨的能力得到了明显提高；值得注意的是，二甲胺及其 OH 氧化产物以及杂质氨和其他物质都得到了跟踪。未来的工作将集中在准确的校准标准和改进样品气体入口上。
