Ion signal detection device and method for ion trap mass spectrometer

Abstract

The invention discloses an ion signal detection device and method for an ion trap mass spectrometer. The device comprises an ion trap mass analyzer, an electrode group and a current or voltage measuring device, wherein the electrode group is mounted on one side, far away from an ion storage area, of an ion extraction electrode in the ion trap mass analyzer, the electrode group is composed of morethan two electrodes which are electrically insulated from each other, and small holes are correspondingly formed in other electrodes except the electrode farthest away from the ion extraction electrode and used for allowing ions separated from the ion trap analyzer to pass through, wherein when the electrode group comprises two electrodes, the current or voltage measuring device is directly connected with the two electrodes; and when the electrode group comprises more than three electrodes, the working power supply is connected with the two electrodes closest to the ion extraction electrode, and the current or voltage measuring device is connected with the two farthest electrodes. The device is simple in structure, low in cost and capable of achieving high-sensitivity testing of ion mass spectrum signals.

Description

technical field [0001] The invention relates to the technical field of mass spectrometry instruments, in particular to an ion signal detection device and method for an ion trap mass spectrometer. Background technique [0002] Ion trap mass spectrometer is the most commonly used mass spectrometry instrument. It has the functions of ion storage, mass analysis and tandem mass spectrometry. It can quickly analyze the chemical composition and molecular structure of substances. It is a common scientific instrument in scientific research and practical applications. . It is also the first choice for miniaturized mass spectrometers. It is widely used in life science, environmental monitoring, food safety, public safety and many other fields. The basic principle of the ion trap mass analyzer is to use suitable electrodes and power sources to generate a suitable electric field distribution in a certain space. The electric field distribution here is often dominated by the electric fie...

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Problems solved by technology

[0012] (1) All electron multipliers will age due to the aging of materials. As a result, the electron multiplication efficiency will become worse and worse, resulting in weaker and weaker mass spectrum signals; therefore, all electron multipliers have a certain service life;

[0013] (2) Different electron multiplier manufacturing companies and different batches of electron multipliers may have different final electron multiplication efficiencies due to differences in materials or processes used, so when used to detect ion signals, it may cause relative The magnitude of the mass spectrum signal generated by the plasma content varies;

[0014] (3) In theory, the total amount of secondary electrons produced by N ions should be equal to N times that of one ion, but the secondary electron emission capabilities of all materials are limited, such as a large number of electrons colliding in a very short period of time. On the surface of the extremely small area of ​​the electron multiplier, the number of secondary electrons generated is often difficult to be a simple multiple of the secondary electrons generated by one electron, resulting in the so-called signal "saturation" phenomenon of ions, resulting in inaccurate quantitative analysis results

[0015] (4) The electron multiplier also often has a mass discrimination effect, that is, the number of secondary electrons produced by an ion with a large mass-to-charge ratio and a large volume is different from that of an ion with a small mass-to-charge ratio and a small volume. As a result, the mass spectrum signal intensity generated by the same number of "large ions" and "small ions" is different, resulting in inaccurate quantitative analysis results

[0016] (5) The microchannel plate electron multiplier is a consumable device installed in the time-of-flight mass spectrometer vacuum chamber, which is not only expensive, but also inconvenient to replace

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