CN101216459A - New Infrared Laser Desorption/Vacuum Ultraviolet Single Photon Ionization Mass Spectrometry Device - Google Patents

Abstract

The invention relates to a novel infrared laser desorption/vacuum ultraviolet single-photon ionization mass spectrometry device for analyzing and detecting biological samples. The method solves the disadvantage that the prior art must use a matrix and cannot analyze some low polarity, small molecular weight and complex mixtures. The structural feature is that a photoionization chamber is provided on one side of the time-of-flight mass spectrometer, an ion introduction hole is provided on the side wall of the photoionization chamber, and an ion introduction device and a sample target are arranged in the chamber; Laser; the other side is equipped with a vacuum ultraviolet light source. The present invention combines infrared laser desorption and vacuum ultraviolet photoionization mass spectrometry technology. It is not necessary to select different substrates according to the samples during testing and analysis, and it is not necessary to carry out complicated sample pretreatment and separation. interference. The invention is especially suitable for the analysis of thermally unstable and non-volatile organic compounds and biomolecules.

Description

New Infrared Laser Desorption/Vacuum Ultraviolet Single Photon Ionization Mass Spectrometry Device

technical field

The invention relates to an analysis and detection device for organic substances, medicines, complex natural products and biological samples, in particular to a photoionization mass spectrometry analysis device.

Background technique

Mass spectrometry is an important method for identifying molecular structures. According to the structure and properties of the analyte, there are various kinds of mass spectrometry sampling, separation systems, ionization techniques and mass analyzers. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS) is a technology that ingeniously combines matrix-assisted laser desorption/ionization and time-of-flight mass spectrometry (TOF). an important direction.

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS) first requires that the sample solution and a specific matrix solution are fully mixed, and after the solvent evaporates, it becomes a semi-crystalline or crystalline state. The matrix can effectively absorb the energy of the 337nm wavelength laser and undergo complex electronic transitions. The matrix ions formed in this process then interact with the sample to be ionized and detected by time-of-flight mass spectrometry. This method not only solves the ionization of highly polar and thermally unstable proteins and polypeptide molecules and the determination of large molecular weight substances, but also its high sensitivity and high quality detection range enable the detection of relative molecular masses up to fmol or even low concentrations of amol Biomacromolecules of hundreds of thousands of daltons become possible, which promotes the wide application and development of mass spectrometry in the field of life sciences. Koichi Tanaka, a scientist from Shimadzu Corporation, Japan, won the 2002 Nobel Prize in Chemistry for his revolutionary contribution to the analysis of proteins, DNA, carbohydrates and sugars by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS).

Although domestic and foreign scientific and technological workers have carried out a lot of fruitful work around matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS), matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS) technology also has some defects: such as the traditional matrix Laser-assisted desorption/ionization mass spectrometry (MALDI-TOFMS) technology needs to select the corresponding matrix according to the different samples. For the same sample, different matrices will give different results. This process is not only time-consuming, but the matrix itself will also bring mass spectrometry background noise. Therefore, samples with small molecular weight cannot be analyzed; matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS) uses a beam of 337nm laser to irradiate the matrix to achieve the purpose of desorption and ionization, but this wavelength of laser will inevitably bring Some fragment ions; matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS) requires relatively high sample preparation, and due to the limitation of the matrix, some samples with low polarity cannot be effectively analyzed and detected. In addition, since the laser only interacts with the matrix, it is not selective for the analyte.

Contents of the invention

In order to solve the shortcomings that the existing matrix-assisted laser desorption/ionization mass spectrometry device must use a matrix, which is prone to fragment ion interference and cannot realize the analysis of some low polarity, small molecular weight and complex organic mixtures, the present invention provides an infrared desorption laser A novel infrared laser desorption/vacuum ultraviolet single-photon ionization mass spectrometry device that is separated from vacuum ultraviolet ionization light in time and space without using a substrate.

The specific structural design scheme is as follows:

A new infrared laser desorption/vacuum ultraviolet single photon ionization mass spectrometry device, mainly including a vacuum system, a sampling system, a vacuum ultraviolet light source, a laser, and a time-of-flight mass spectrometer; the sampling system includes a sample target; the time-of-flight mass spectrometer is equipped with ion acceleration Electrode, ion extracting electrode, ion focusing mirror, ion reflector and microchannel plate; It is characterized in that:

A photoionization chamber is provided on one side of the time-of-flight mass spectrometer, and an ion introduction hole is provided on the side wall of the photoionization chamber corresponding to the gap between the ion acceleration electrode and the ion extraction electrode. The photoionization chamber corresponding to the hole is provided with an ion guider, and the other end of the ion guider is correspondingly provided with a sample target, and a convex lens is provided on the side wall of the photoionization chamber corresponding to the sample target, and a laser is provided outside the convex lens; A window is provided on the side wall of the corresponding photoionization chamber on the other side, and a vacuum ultraviolet light source is provided outside the window;

A vacuum port is provided on one side of the photoionization chamber.

Beneficial technical effect of the present invention is embodied in following several aspects:

1. The present invention combines infrared laser desorption and vacuum ultraviolet photoionization mass spectrometry technology. When testing and analyzing, the sample to be tested is directly deposited on the sample target, and there is no need to select different substrates according to the sample, and there is no need for complicated sample pretreatment and separation. . This not only makes the entire analysis process efficient and fast, but also avoids the interference of the matrix on the mass spectrometry signal.

2. The present invention uses infrared lasers to achieve sample desorption, which is a physical process that does not involve the chemical interaction between the sample and the target, and is suitable for molecules that are not easily volatile and thermally unstable. In the case of keeping the laser power relatively low, neutral molecules can be desorbed without generating fragment ions.

3. Since the desorption laser and ionization light are separated in time and space, they can be optimized separately to obtain better signal-to-noise ratio and sensitivity.

4. The present invention adopts vacuum ultraviolet single photon ionization as the ionization technology. Vacuum ultraviolet single photon ionization technology has no discrimination effect on the measured molecules, and can ionize molecules with different polarities and different structures. The vacuum ultraviolet light source can be a vacuum ultraviolet lamp, which is small in size and cheap in price. The photon energy can cover most organic molecules and the photon intensity is high. It is an ideal light source; as an advanced light source, synchrotron radiation has high brightness and high accuracy. With the advantages of straightness, continuously adjustable wavelength, and high resolution, it can not only achieve near-threshold ionization of all organic and biological samples to be tested, but also obtain the ionization energy of each substance to be tested by changing the photon energy and scanning the photoionization efficiency spectrum. This not only makes it easy to analyze complex mixtures, but also distinguishes isomers by differences in ionization energy. Other light sources that can generate vacuum ultraviolet bands, such as lasers, can also be used as ionization sources.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the present invention,

Detailed ways

The present invention will be further described through the embodiments below in conjunction with the accompanying drawings.

Example:

The new infrared laser desorption/vacuum ultraviolet single-photon ionization mass spectrometry device mainly includes a vacuum system, a sampling system, a vacuum ultraviolet light source 12, a laser 4 and a time-of-flight mass spectrometer 10; the sampling system includes a sample target 2; the time-of-flight mass spectrometer 10 An ion accelerating electrode 8 , an ion extracting electrode 9 , an ion focusing mirror 14 , an ion reflector 7 and a microchannel plate 6 are provided.

One side of the time-of-flight mass spectrometer 10 is provided with a photoionization chamber 1, and an ion introduction hole is opened on the side wall of the photoionization chamber corresponding to the gap between the ion acceleration electrode 8 and the ion extraction electrode 9, and a vacuum valve is installed on one side of the ion introduction hole 15. An ion guider 5 is installed in the photoionization chamber corresponding to the ion introduction hole, and the sample target 2 is correspondingly arranged at the other end of the ion guider 5, and a convex lens 3 is installed on the side wall of the photoionization chamber corresponding to the sample target 2 A laser 4 is installed inside the photoionization chamber corresponding to the convex lens 3; a window 13 is installed on the side wall of the photoionization chamber on the other side corresponding to the sample target 2, and a vacuum ultraviolet ray is installed on the outside of the photoionization chamber corresponding to the window 13 light source 12;

One side of the time-of-flight mass spectrometer 10 is provided with a vacuum port 11;

One side of the photoionization chamber is provided with a vacuum port 11 .

The working principle of this device is as follows:

Firstly, the sample to be tested is deposited on the surface of the sample target 2, and the sample target 2 is introduced into the photoionization chamber 1 by a suitable sample introduction method. The pulsed infrared light emitted by the laser 4 is focused by the convex lens 3 from one side of the photoionization chamber 1 and then incident on the target carrying the sample to desorb the sample to be tested; the second beam of ionized light emitted by the vacuum ultraviolet light source 12 is emitted from the other side Pass through the photoionization chamber window 13, incident on the sample target 4 several millimeters above, then the desorbed neutral sample molecules are "softly" ionized into molecular ions through the vacuum ultraviolet radiation region (if using a synchrotron radiation light source, it can also be ionized by Change the photon energy to control the generation of fragment ions). These ions are transported by ion guide 5 to time-of-flight mass spectrometer 10 . The ions entering the mass spectrometer enter the ion accelerating electrode 8 driven by the pulsed electric field of the ion extracting electrode 9, and the accelerated ions enter the field-free area to drift freely, and then are focused by the ion lens 14 and reflected by the ion reflecting electrode 7 before being reflected by the microchannel plate 6 Receive and record. The pulse timing of the laser 4 and the mass spectrometry ion extraction electrode 9 is controlled by a pulse delay generator, as shown in FIG. 1 .

Claims (1)

1. A new infrared laser desorption/vacuum ultraviolet single photon ionization mass spectrometry device, mainly including a vacuum system, a sampling system, a vacuum ultraviolet light source, a laser, and a time-of-flight mass spectrometer; the sampling system includes a sample target; the time-of-flight mass spectrometer is equipped with An ion accelerating electrode, an ion extracting electrode, an ion focusing mirror, an ion reflector and a microchannel plate; it is characterized in that: A photoionization chamber is provided on one side of the time-of-flight mass spectrometer, and an ion introduction hole is provided on the side wall of the photoionization chamber corresponding to the gap between the ion acceleration electrode and the ion extraction electrode. The photoionization chamber corresponding to the hole is provided with an ion guider, and the other end of the ion guider is correspondingly provided with a sample target, and a convex lens is provided on the side wall of the photoionization chamber corresponding to the sample target, and a laser is provided outside the convex lens; A window is provided on the side wall of the corresponding photoionization chamber on the other side, and a vacuum ultraviolet light source is provided outside the window; A vacuum port is provided on one side of the photoionization chamber.

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