A fully automated electrodynamical ion funnel proton transfer reaction mass spectrometer for the use on research and passenger aircraft

五年多来，用于检测各种有机化合物的质子转移反应质谱仪（PTRMS）已成功地用于医疗应用（例如呼吸分析）和大气科学。自2005年5月以来，用于测量丙酮、乙腈、过氧乙酰硝酸盐（PAN）和其他化合物的PTRMS被安装在汉莎航空公司加勒比海项目空客A340-600客机上的改装空运集装箱中。目前最复杂的PTRMS的精度为30-200 pptv√Hz，具体取决于物种和混合比例（1 pptv = 10-12 mol/mol）。在对流层上层和平流层下层快速移动的飞机上使用所需的精度（和准确度），其中感兴趣的物种的混合比率在10-1000 pptv的数量级，是一个~10的系数。与电动力离子漏斗相结合有望有效地提高PTRMS的测量不确定度。在目前的PTRMS中，95%以上的离子在PTRMS反应室（漂移管）壁上丢失，只有约1%的初级离子最终到达检测器（四极杆质谱仪）。离子通道是一种能够几乎定量地引导离子通过离子漂移区域的系统，其中压力约为1-10 hPa，因此平均自由程长度低于~1mm。本方案的目的是扩大PTRMS漂移管与电动力离子漏斗。预期的灵敏度提高在10的数量级。到目前为止，离子漏斗技术（由Shaffer等人，1997年提出）仅用于电喷雾质谱分析和~ 200amu以上的分子质量。一些理论研究表明，改进的离子漏斗应该能够引导质量低至20amu的光离子通过漂移管。项目分为三个阶段：第一阶段，开发、建造和安装一个低质量离子漏斗及其射频电源；在第二年，系统应在实验室中进行各种条件（压力、离子漏斗频率、直流和交流电压）的广泛测试，并在必要时进行修改；在第三年，一个离子漏斗PTRMS将在加勒比海空中客车上飞行，并对数据进行分析，除其他外，量化在现场条件下测量不确定度的改进。

For more than five years proton-transfer-reaction mass spectrometers (PTRMS) for the detection of diverse organic compounds are successfully used for medical applications (e.g. breath analysis) and in atmospheric sciences. Since May 2005 a PTRMS for measuring acetone, acetonitrile, peroxyacetyl nitrate (PAN) and other compounds is installed in a modified airfreight container that is deployed onboard an Airbus A340-600 passenger aircraft of Lufthansa AG, project CARIBIC. The precision of the most sophisticated PTRMS currently is 30-200 pptv√Hz, depending on species and mixing ratio (1 pptv = 10-12 mol/mol). The desired precision (and accuracy) for the use on fast 2 moving aircraft in the upper troposphere and lower stratosphere, where the mixing ratios of the species of interest are in the order of 10-1000 pptv, is a factor of ~10 higher. A powerful technique to significantly improve the measurement uncertainty of PTRMS is expected to be the combination with an electro-dynamical ion funnel. In the present PTRMS, more than 95% of all ions get lost on the walls of the PTRMS reaction chamber (drift tube) and only ~1% of all primary ions finally reach the detector (quadrupole mass spectrometer). Ion funnels are systems that are able to guide ions almost quantitatively through ion drift regions where the pressure is about 1-10 hPa and thus the mean free path length below ~1mm. Objective of this proposal is to extent the PTRMS drift tube with an electro-dynamical ion funnel. The expected sensitivity improvement is in the order of 10. Until now, the ion funnel technique (proposed by Shaffer et al., 1997) has only been used for electrospray mass spectrometry and for molecule masses above ~200 amu. A few theoretical studies indicate that a modified ion funnel should be able to guide also light ions with masses as low as 20 amu through a drift tube. The proposed project consists of three phases: in year 1, a low-mass ion funnel and its rf power supply shall be developed, constructed and installed into a PTRMS; in year 2, the system shall extensively be tested in the laboratory under various conditions (pressures, ion funnel frequencies, DC, and AC voltages) and if necessary modified; and in year 3, an ion funnel PTRMS shall be flown onboard the CARIBIC Airbus and the data shall be analysed, inter alia, to quantify the improvement of the measurement uncertainty under field conditions.