小型质谱仪为现场原位检测提供了可行方案，在生命科学、环境监测、食品安全、国防安全等领域具有良好应用前景。然而仪器小型化是以性能的损失为代价的，这大大限制了其应用。为此本文针对持续进样大气压接口的小型差压真空腔离子阱质谱，通过理论、仿真、实验相结合的研究手段，从气流分布、离子传输、质量分析等环节对仪器性能进行优化，并开发了四极杆-离子阱差压真空腔质谱以及提高其性能的新方法。具体工作包括： (1)通过对小型漏斗-离子阱差压真空腔质谱仪内气流的仿真和实验研究，发现过大的气流会影响仪器稳定性与分辨率。通过调控取样锥孔径，并加入一个中间透镜使离子阱远离锥孔，可有效降低气流的影响，将分辨率提高为原来的3倍，强度稳定性提高为原来的2倍，质量飘移降低为原来的1/3。 (2)针对上述质谱仪中小型漏斗内离子歧视问题，通过理论分析和实验研究证明了其表现为质量歧视和碰撞截面歧视两方面。为了减弱该歧视，本文提出漏斗幅值扫描式离子阱进样方法，使得全范围内的离子传输效率得到提高。此外通过对漏斗直流梯度、射频幅值以及工作气压等参数的优化，仪器对罗红霉素的检出限低至1ng/mL，动态范围达到4个数量级。 (3)为了避免漏斗离子歧视，提高仪器选择性，设计开发了低真空一级腔四极杆，高真空二级腔离子阱的新型差压真空腔质谱实验平台。针对采用的矩形离子阱，通过仿真与实验研究了X极板开槽尺寸对性能的影响，得到全尺寸为5mm×4mm×25mm矩形离子阱的优化开槽尺寸为0.6mm×18mm。 (4)针对本文所开发的四极杆-离子阱差压真空腔质谱仪提出了四种分析新方法，包括：反向世俗频率扫描模式，能降低对射频电源的要求，提高分析范围；持续世俗频率扫描模式，可提高分析效率，单次分析周期小于20ms；储存四极阱-矩形阱模式，能提高仪器灵敏度，最优离子采样率超过96%；分析四极阱-矩形阱模式，降低了空间电荷效应的影响，提高仪器分辨率。 以上新方法证明了四极杆-离子阱差压真空腔质谱仪具有很好的扩展性，同时结合四极杆的离子选择性以及离子阱的时间串级质谱能力和高气压耐受能力，其有望成为一种良好的质谱仪小型化选择。本文的研究成果对推动质谱仪的小型化，同时提升仪器性能扩展其应用范围有积极作用。

The miniature mass spectrometer provides a feasible solution for in-site analysis and field detection, and it has very good application prospects in the fields of life science, environmental monitoring, food safety, national defense and safety. However, it is generally recognized that the miniaturization is achieved at the cost of reducing the system performance, which greatly limits its application. In this thesis, the miniature ion trap mass spectrometer with dual pressure chambers and continuous atmospheric pressure interface is investgated by the method of theory, simulation and experiment. The instrument performance is optimized from the aspects of gas flow distribution, ion transmission and mass analysis. On this basis, a novel quadrupole-ion trap mass spectrometer with dual pressure vacuum chamber as well as some new methods to improve its performance are developed. Detailed work includes: (1) Through the simulation and experimental optimization of the airflow in a miniature funnel-ion trap dual pressure vacuum chamber mass spectrometer, it is found that excessive gas flow affects stability and resolution. By reducing the inner diameter of the skimmer and adding an additional lens element to move the ion trap far away from the skimmer hole, the impact of the gas flow can be effectively reduced, the resolution is increased to 3 times, the ion abundance stability is increased to 2 times, and the mass drift is reduced to 1/3. (2) For the ion discrimination problem of the funnel in the above mass spectrometer, the Runge–Kutta algorithm is used to calculate the trajectories of ions in the funnel under the collision with gas molecules. It is theoretically and empirically proved that, the ion discrimination in the funnel shows two aspects: mass discrimination and collision cross-section discrimination. To overcome the ion discrimination, RF amplitude scanning method is introduced during the injection section of ion trap to improve ion transmission efficiency within all mass range. After the ion funnel optimization, the dynamic range of the instrument concentration reached 4 orders of magnitude. The detection limit of roxithromycin reached a low level of 1 ng/mL. (3) In order to completely avoid the funnel ion discrimination and improve the instrument selectivity, a new mass spectrometry experimental platform with dual pressure vacuum chamber is designed and characterized. The studied system constituted a quadrupole in the first chamber and a rectilinear ion trap in the second chamber. The ejection-slit dimensions of the rectilinear ion trap are also optimized. Through the optimization experiments on resolution and sensitivity, it is found that for a rectangular ion trap with a “full-scale" of 5 mm × 4 mm × 25 mm, the optimized slit dimension is 0.6 mm × 18 mm. (4) Four novel analytical methods for the quadrupole-ion trap mass spectrometer with dual pressure vacuum chamber are developed in this paper, including: Reverse secular frequency scanning mode, which can reduce the requirements of RF power supply and improve the analysis range; Continuous secular frequency scanning mode, in which the single analysis period is less than 20 ms and the analysis efficiency can be improved; Storage quadrupole ion trap–rectilinear ion trap mode, in which the sensitivity and signal intensity can be increased, and the optimal ion utilization rate is higher than 96%; Analysis quadrupole ion trap–rectilinear ion trap mode, which can reduce the space charge effect and increase the resolution. The new method above proves that the quadrupole-ion trap mass spectrometer with dual pressure vacuum chambers has good scalability. Combined with the ion selectivity of quadrupole and the intrinsic tandem mass spectrometry capability and the high gas pressure tolerance of ion trap, it is expected to become a good miniaturization option for mass spectrometers. The research results in this thesis have a positive effect on promoting the miniaturization of mass spectrometers while improving its performance and expanding its application range.