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）成功地用于医学应用（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、过氧乙酰硝酸酯（PAN）和其他化合物的PTRMS安装在汉莎航空公司的空中客车A340-600客机上的改装空运集装箱中，项目CARIBIC。目前最复杂的PTRMS的精度为30-200 pptv kHz，取决于物质和混合比（1 pptv = 10-12 mol/mol）。在对流层上部和平流层下部快速移动的飞行器上使用所需的精确度（和准确度）高出约10倍，其中感兴趣的物质的混合比在10-1000 pptv的数量级。一个强大的技术，以显着提高PTRMS的测量不确定度，预计将与电动离子漏斗的组合。在目前的PTRMS中，超过95%的所有离子在PTRMS反应室（漂移管）的壁上丢失，并且只有~1%的所有初级离子最终到达检测器（四极质谱仪）。离子漏斗是能够几乎定量地引导离子通过离子漂移区的系统，其中压力约为1-10 hPa，因此平均自由程长度低于约1 mm。 本提案的目的是延长PTRMS漂移管与电动离子漏斗。预期的灵敏度改进在10的数量级。到目前为止，离子漏斗技术（由Shaffer等人提出，1997）仅用于电喷雾质谱法和分子质量高于~200 amu。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20 amu的轻离子通过漂移管。该项目分三个阶段进行：第一年，将研制、建造低质量离子漏斗及其射频电源，并将其安装到PTRMS中;第二年，将在实验室中对该系统进行各种条件下的广泛测试（压力、离子漏斗频率、DC和AC电压），必要时进行修改;在第3年，将在CARIBIC空中客车上飞行离子漏斗PTRMS，并对数据进行分析，除其他外，以量化实地条件下测量不确定性的改善。

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.