An open atmospheric pressure ionization source

Abstract

The present application relates to the ionization source in analytical instrument, specifically, an open atmospheric pressure ionization source, including sample stage, the middle part of sample stage is sample placement area, the thermal desorption lamp is arranged above the sample placement area of sample stage, the light outlet of thermal desorption lamp faces sample placement area, and the emitted light is irradiated on sample placement area;More than one VUV ionization lamp is arranged on the outside of sample placement area above sample stage, and the light outlet of VUV ionization lamp faces the upper area of sample placement area, and the emitted light is irradiated on the upper area of sample placement area.The ionization source can be used for analyzing one or more than two samples in gaseous, solid and liquid samples.

Description

Technical Field

[0001] This invention relates to ionization sources in analytical instruments, specifically an open atmospheric pressure ionization source. In particular, it combines a thermal desorption lamp with a VUV lamp, using the thermal desorption lamp to desorb solid and liquid samples to generate sample vapor, overlapping the desorption zone and the ionization zone, achieving efficient sample ionization without the need for a carrier gas, avoiding sample dilution caused by a carrier gas, thereby improving detection sensitivity. Background Technology

[0002] Ionization sources are one of the key technologies in ion-type detection instruments such as mass spectrometry and ion mobility spectrometry. Traditional ion mobility spectrometry commonly uses radioactive ionization sources. 63 Ni ionization source. 63 Ni can emit beta rays with an average energy of 17 keV. After undergoing a series of complex reactions with the carrier gas, it finally forms reagent ions H₃O. + (Positive ion detection mode) and O2 _ (Negative ion detection mode) The reagent ions react with the sample to ionize it. Radioactivity 63 Ni ionization sources are favored by scientists due to their simplicity, stability, and lack of external power supply. However, the safety inspections and special safety measures required due to their radioactivity bring many troubles to their practical application. Additionally... 63 The ion concentration produced by Ni ionization sources is not high enough, resulting in weak ion mobility spectra and a small linear range. Therefore, in recent years, researchers have been actively seeking non-radioactive ionization sources to replace traditional radioactive ones. 63 Ni ionization sources. Several atmospheric pressure ionization sources used for mass spectrometry include APCI, DART, DESI, corona discharge ionization sources, and electrospray ionization sources.

[0003] When the aforementioned ionization source is used to ionize solid and liquid samples, the thermal desorption region and the ionization region are often independent of each other. Therefore, a carrier gas is needed to carry the thermal desorption vapor of the solid and liquid samples into the ionization region. However, the carrier gas dilutes the sample vapor, leading to a decrease in sensitivity. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method that combines a thermal desorption lamp with a VUV lamp, uses the thermal desorption lamp to desorb solid and liquid samples to generate sample vapor, overlaps the desorption zone and the ionization zone, achieves efficient ionization of the sample without the need for a carrier gas, avoids sample dilution caused by the carrier gas, and thus improves detection sensitivity.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An open-type atmospheric pressure ionization source

[0007] It includes a sample stage, with a sample placement area in the middle. A thermal desorption lamp is installed above the sample placement area on the sample stage. The light outlet of the thermal desorption lamp faces the sample placement area, and the emitted light illuminates the sample placement area.

[0008] One or more VUV ionization lamps are installed on the outside of the sample placement area above the sample stage. The light outlet of the VUV ionization lamp faces the area above the sample placement area, and the emitted light illuminates the area above the sample placement area.

[0009] The aforementioned ionization source,

[0010] A pair of parallel, spaced-apart annular electrodes are provided at the light outlet of each VUV ionization lamp. The emitted light from the VUV ionization lamp illuminates the area above the sample placement area through the middle of the annular electrodes. The VUV ionization lamp, annular electrodes A and B constitute a reagent ion generation system. The light outlet of the VUV ionization lamp and the annular electrodes are coaxial and placed sequentially.

[0011] The focal point of the emitted light from the thermal desorption lamp is located in or near the sample placement area; a desorption ionization zone is formed between the thermal desorption lamp and the sample placement area.

[0012] The ionization source is provided with an auxiliary reagent storage container above the sample stage. The auxiliary reagent storage container is provided with a reagent chamber opening. The reagent outlet is located on one side of the area above the sample placement area and below the emission light path of the VUV ionization lamp.

[0013] The ionization source has a reagent chamber opening located below the region between the annular electrodes A and B.

[0014] The ionization source has a groove on the sample stage in the sample placement area, which serves as a sample slot.

[0015] The ionization source, the thermal desorption lamp, is an infrared lamp, a laser, or its triggering radiation is a pulsed heating lamp.

[0016] The ionization source is characterized in that: the annular electrodes A and B are circular or square rings.

[0017] The ionization source can be used to analyze one or more of gaseous, solid, and liquid samples.

[0018] The advantages of this invention are as follows: This invention provides a method that combines a thermal desorption lamp with a VUV lamp, using the thermal desorption lamp to desorb solid and liquid samples to generate sample vapor, overlapping the desorption zone and the ionization zone, achieving efficient ionization of the sample without the need for a carrier gas, avoiding sample dilution caused by the carrier gas, thereby improving detection sensitivity. Attached Figure Description

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0020] Figure 1 Schematic diagram of an open atmospheric pressure ionization source. Sample stage (1), thermal desorption lamp (2), VUV ionization lamp (3), sample tank (4), ring electrode (5) and (6), auxiliary reagent storage container (7), reagent opening (8), desorption ionization zone (9).

[0021] Figure 2 The mass spectrum of ketamine was determined by coupling an open atmospheric pressure ionization source with an ion trap mass spectrometer. Detailed Implementation

[0022] An open-type atmospheric pressure ionization source

[0023] The sample stage 1 is included. The middle part of the sample stage 1 is the sample placement area. A thermal desorption lamp 2 is installed above the sample placement area of ​​the sample stage 1. The thermal desorption lamp 2 is a 75W halogen lamp. The light outlet of the thermal desorption lamp 2 faces the sample placement area, and the emitted light illuminates the sample placement area. The sample placement area is located at the focal point of the halogen lamp.

[0024] One or more VUV ionization lamps 3 are set on the outside of the sample placement area above the sample stage 1. The VUV ionization lamps 3 are low-voltage radio frequency krypton lamps. The light outlet of the VUV ionization lamps 3 faces the area above the sample placement area, and the emitted light illuminates the area above the sample placement area.

[0025] A pair of parallel and spaced annular electrodes are provided at the light outlet of each VUV ionization lamp 3. The emitted light from the VUV ionization lamp 3 illuminates the area above the sample placement area through the middle of the annular electrodes. The VUV ionization lamp 3, the annular electrodes A5 and B6 constitute a reaction reagent ion generation system. The light outlet of the VUV ionization lamp 3 and the annular electrodes are coaxial and placed in sequence.

[0026] The focal point of the emitted light from the thermal desorption lamp 2 is located in or near the sample placement area; a desorption ionization region 9 is formed between the thermal desorption lamp 2 and the sample placement area;

[0027] An auxiliary reagent storage container 7 is provided above the sample stage 1. The auxiliary reagent storage container 7 is provided with a reagent chamber opening 8. The auxiliary reagent is acetone. The reagent outlet is located on one side of the area above the sample placement area and below the light path emitted by the VUV ionization lamp 3.

[0028] The reagent chamber opening 8 is located below the area between the annular electrodes A and B, and the reagent chamber opening 8 is a circular hole with a diameter of 3 mm;

[0029] The sample stage 1 in the sample placement area is provided with a groove that serves as a sample slot 4;

[0030] The thermal desorption lamp is a halogen infrared heating lamp;

[0031] The annular electrodes A and B are circular rings with inner and outer diameters of 10 cm and 20 cm, respectively, and the distance between A and B is 5 mm.

[0032] This invention utilizes an open atmospheric pressure ionization source. The VUV lamp emits photons with an energy of 10.6 eV, the auxiliary reagent storage container 7 is acetone, the thermal desorption lamp 2 is a halogen lamp, and the sample placed in the groove of the sample holder 4 is ketamine. For detailed apparatus, see [link to apparatus description]. Figure 1 .

[0033] The above-described open atmospheric pressure ionization source is coupled with an ion trap mass spectrometer. The sample detection process is as follows: ketamine in the groove of sample cell 4 is heated by a halogen lamp, forming gaseous molecules that volatilize into the desorption ionization region 9. Simultaneously, auxiliary reagents enter the region between the ring electrodes A5 and B6 through reagent opening 8, forming reactive ions under VUV light. These ions then enter the desorption ionization region 9 due to the voltage difference between the ring electrodes A5 and B6. Ketamine collides with the reactive ions, resulting in efficient ionization. The sampling capillary of the ion trap mass spectrometer extracts ions from the desorption ionization region 9 for analysis and detection. Figure 2 Mass spectra of ketamine obtained by coupling an open atmospheric pressure ionization source with an ion trap mass spectrometer are presented.

Claims

1. An open-type atmospheric pressure ionization source, characterized in that: Includes a sample stage (1), the middle of the sample stage (1) is a sample placement area, and a thermal desorption lamp (2) is set above the sample placement area of ​​the sample stage (1). The light outlet of the thermal desorption lamp (2) faces the sample placement area, and the emitted light illuminates the sample placement area. One or more VUV ionization lamps (3) are set on the outside of the sample placement area above the sample stage (1). The light outlet of the VUV ionization lamp (3) faces the area above the sample placement area, and the emitted light illuminates the area above the sample placement area. A pair of parallel and spaced annular electrodes are provided at the light outlet of each VUV ionization lamp (3). The emitted light from the VUV ionization lamp (3) irradiates the area above the sample placement area through the middle of the annular electrodes. The VUV ionization lamp (3), annular electrodes A, B (5) and (6) constitute a reaction reagent ion generation system. The light outlet of the VUV ionization lamp (3) and the annular electrodes are coaxial and placed in sequence. The focal point of the emitted light from the thermal desorption lamp (2) is located in or near the sample placement area; a desorption ionization region (9) is formed between the thermal desorption lamp (2) and the sample placement area.

2. The ionization source according to claim 1, characterized in that: An auxiliary reagent storage container (7) is provided above the sample stage (1). The auxiliary reagent storage container (7) is provided with a reagent chamber opening (8). The reagent outlet is located on one side of the area above the sample placement area and below the emission light path of the VUV ionization lamp (3).

3. The ionization source according to claim 2, characterized in that: The reagent chamber opening (8) is located below the region between the annular electrodes A, B (5) and (6).

4. The ionization source according to claim 1 or 2, characterized in that: The sample stage (1) in the sample placement area is provided with a groove that serves as a sample slot (4).

5. The ionization source according to claim 1, characterized in that: The thermal desorption lamp is an infrared lamp, a laser, or a pulsed heating lamp that is triggered by radiation.

6. The ionization source according to claim 1, characterized in that: The ring electrodes A, B (5) and (6) are circular or square rings.

7. The ionization source according to claim 1 can be used to analyze one or more of gaseous, solid, and liquid samples.

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