CN212517113U

CN212517113U - Radio frequency discharge excited methylene dichloride induced proton transfer reaction ion source

Info

Publication number: CN212517113U
Application number: CN202022039613.XU
Authority: CN
Inventors: 束继年; 黄靖云; 杨波
Original assignee: University of Chinese Academy of Sciences
Current assignee: University of Chinese Academy of Sciences
Priority date: 2020-09-17
Filing date: 2020-09-17
Publication date: 2021-02-09
Anticipated expiration: 2030-09-17

Abstract

The invention provides a radio-frequency discharge excited methylene dichloride induced proton transfer reaction ion source which comprises an air inlet, a reaction area and an ion outlet, wherein a discharge electrode I, a PEEK insulating ring I, a radio-frequency electrode, a PEEK insulating ring II and a discharge electrode II are coaxially distributed and are sequentially connected, the ionization area and the ion outlet are positioned on the same axis, the discharge electrode I is connected with the front part of an ionizer, the discharge electrode II is connected with the rear part of the ionizer, the air inlet is positioned at the front part of the ionizer, and the ion outlet is positioned at the rear part of the ionizer. Dichloromethane and a detected object enter the cavity of the ionizer through the air inlet, the dichloromethane is excited by radio frequency discharge, the generated excited dichloromethane induces water molecules and the object to be detected to perform proton transfer reaction in an ionization region to generate an ionized detected object, and the ions of the object to be detected are output from the ion outlet of the ionizer along with carrier gas. The invention uses radio frequency to excite the dichloromethane, has low cost and simple structure, and does not have the intensity continuous attenuation phenomenon common in the vacuum ultraviolet excitation method.

Description

Radio frequency discharge excited methylene dichloride induced proton transfer reaction ion source

Technical Field

The invention relates to a radio frequency discharge excited methylene dichloride induced proton transfer reaction ion source, and provides a novel ionization device for mass spectrum detection of organic matters containing oxygen, nitrogen, sulfur and the like.

Background

Mass spectrometry is a traditional materializationA method of chemical component analysis which uses the mass to charge ratio and the fragmentation pattern of ions to provide information on the molecular structure of a substance. Ionization technology is an indispensable core part in a mass spectrometry technology system, and the ionization mode and the ionization efficiency of the ionization technology are main factors determining the mass spectrometry capacity and the detection sensitivity. At present, the ionization techniques used by ion sources of mass spectrometers are mainly electron impact ionization, single photon ionization, Penning ionization and chemical ionization. The traditional ionization technology has low ionization efficiency and sensitivity because of operating under the condition of high vacuum. The literature reports an ionization efficiency of 10 for electron impact ionization^-6~10^-4The corresponding instrument sensitivity is in the order of ppbv. Conventional single photon ionization sources typically have lower ionization efficiency than electron impact ionization sources due to the high vacuum level. The low-pressure photoionization is a photoionization technology developed in recent years, the retention time of an object to be detected in a photoionization region is prolonged due to the increase of the air pressure in an ion source, the ionization efficiency is greatly improved compared with that of an ionization source for single photon ionization, and the detection sensitivity of an instrument reaches the order of sub-pptv. In recent years, penning ionization reaction is utilized to directly ionize volatile and semi-volatile organic gases, and the ionization efficiency reaches 10^-3. Chemical ionization charges molecules of an analyte through ion-molecule reaction, and the ionization efficiency of a typical chemical ionization ion source is about 10^-5As a typical chemical ionization mass spectrometer, a proton transfer reaction mass spectrometer has a detection sensitivity of several hundred cps pptv^-1。

The excited methylene dichloride induced proton transfer technology is an ionization method which is newly discovered in our laboratory and can efficiently generate organic ions containing oxygen, nitrogen, sulfur and the like. Taking methylene chloride as an example of the reactant, CH₂Cl₂Firstly, vacuum ultraviolet light is absorbed to generate [ CH ] in ion pair state₂Cl⁺-Cl^-]It is associated with trace H in carrier gas₂O and some polar organic matters interact to generate reaction compound and initiate recombination of compound molecules, and finally, the light energy and the recombination energy are simultaneously released to drive H₂The O molecule transfers the proton to the analyte A to generate an equivalent amount of AH⁺And Cl^-. The reaction process is as follows:

CH₂Cl₂ + hυ→ [CH₂Cl⁺-Cl^-]* (1)

[CH₂Cl⁺-Cl^- ]* + H₂O → [H₂O-CH₂Cl⁺-Cl^-] (2)

[H₂O-CH₂Cl⁺-Cl^-] + A → AH⁺ + CH₂O + HCl + Cl^- (3)

the excited methylene dichloride induced proton transfer technology is a soft ionization technology, the mass spectrum characteristics are similar to those of vacuum ultraviolet ionization, and the obtained mass spectrum is simple and clear. The ionization efficiency of the ionization technology to the common oxygen-containing volatile organic compounds can reach 10^-3~10^-2And the ionization efficiency of some polar organic matters with strong electrophilic or hydrophilic groups reaches 10^-1For example, the ionization efficiency of the paranitroaromatic hydrocarbon is 28%, and the detection sensitivity reaches thousands of cps pptv^-1. Currently, the proton transfer technology induced by the excited dichloromethane utilizes vacuum ultraviolet light to excite the dichloromethane, but the generation efficiency of the vacuum ultraviolet light is very low, the service life of the magnesium fluoride window is limited, and the concentration of the excited dichloromethane and the service time of an ion source are limited. The radio frequency can form discharge under the condition of low pressure so as to excite gas, the device has the advantages of low cost and simple structure, and the radio frequency discharge is utilized to excite dichloromethane to generate an excited state dichloromethane to induce the generation of proton transfer reaction, so that a novel ionization device is provided for mass spectrum detection of organic matters containing oxygen, nitrogen, sulfur and the like.

Disclosure of Invention

For further developing the proton transfer reaction technology induced by the excited state dichloromethane, the utility model provides a radio frequency discharge excited dichloromethane induced proton transfer reaction ion source.

The utility model discloses a technical scheme who adopts is: the radio frequency discharge excited methylene dichloride induced proton transfer reaction ion source comprises an air inlet, a reaction area and an ion outlet, wherein the reaction area comprises a discharge electrode I, a PEEK insulating ring I, a radio frequency electrode, a PEEK insulating ring II, a discharge electrode II and an ionization area.

The radio-frequency discharge excited methylene dichloride induced proton transfer reaction ion source comprises a discharge electrode I, a PEEK insulating ring I, a radio-frequency electrode and a PEEK insulating ring II, wherein the discharge electrode II, an ionization region and an ion outlet are located on the same axis, the PEEK insulating ring I is arranged between the discharge electrode I and the radio-frequency electrode, and the PEEK insulating ring II is arranged between the discharge electrode II and the radio-frequency electrode.

According to the radio-frequency discharge excited methylene chloride induced proton transfer reaction ion source, the discharge electrode I is connected with the front part of the ionizer, the discharge electrode II is connected with the rear part of the ionizer, the air inlet is positioned at the front part of the ionizer, and the ion outlet is positioned at the rear part of the ionizer.

According to the radio-frequency discharge excited methylene chloride induced proton transfer reaction ion source, methylene chloride and a detected object enter the cavity of the ionizer through the sample inlet, methylene chloride is excited by radio-frequency discharge to generate excited methylene chloride, the excited methylene chloride induces proton transfer reaction between water molecules and the object to be detected in the ionization region to generate ionized object to be detected, and the object ions to be detected are output from the ion outlet of the ionizer along with carrier gas.

According to the radio-frequency discharge excited dichloromethane-induced proton transfer reaction ion source, excited dichloromethane is generated by radio-frequency discharge excited dichloromethane, and ions of the object to be detected are generated by excited dichloromethane-induced proton transfer reaction.

The invention has the advantages of low cost, simple structure and no continuous attenuation phenomenon of the light intensity of the vacuum ultraviolet light source when the radio frequency discharge is used for exciting the dichloromethane.

Drawings

FIG. 1 is a schematic diagram of a radio frequency discharge excited methylene chloride induced proton transfer reaction ion source. The ionization device comprises a gas inlet 1, a gas inlet 2, an ionizer front 3, a discharge electrode I, 4, a PEEK insulating ring I, 5, a radio frequency electrode 6, a PEEK insulating ring II, 7, a discharge electrode II, 8, an ionization region 9, an ionizer rear 10, a baffle plate 11 and an ion outlet.

Detailed Description

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings: the embodiments are carried out on the premise of the technical scheme of the invention, and the protection scope of the invention is not limited by the following embodiments.

Step 1: dichloromethane and a detected object enter the cavity of the ionizer through the air inlet (1);

step 2: exciting dichloromethane by radio frequency discharge to generate excited dichloromethane;

and step 3: the excited methylene dichloride induces the water molecules and the object to be detected to generate proton transfer reaction in the ionization region (8) to generate an ionized object to be detected;

and 4, step 4: the ions of the object to be detected are output along with the carrier gas from the ion outlet (11), and the output ions are detected and analyzed by the mass analysis device.

Claims

1. Radio frequency discharges and arouses proton transfer reaction ion source of dichloromethane induction, and the device of its realization comprises air inlet (1), ionizer front portion (2), discharge electrode I (3), PEEK insulating ring I (4), radio frequency electrode (5), PEEK insulating ring II (6), discharge electrode II (7), ionization region (8), ionizer rear portion (9), baffle (10) and ion outlet (11).

2. The radio frequency discharge excited methylene chloride induced proton transfer reaction ion source of claim 1, wherein: dichloromethane and an object to be detected enter the ionizer through the air inlet (1), the dichloromethane is excited by radio frequency discharge to generate excited dichloromethane, the excited dichloromethane induces water molecules and the object to be detected to generate proton transfer reaction in the ionization region (8) to generate ionized object to be detected, generated ions are output along with carrier gas from the ion outlet (11), and the output ions are detected and analyzed by the mass analyzer.

3. The radio frequency discharge excited methylene chloride induced proton transfer reaction ion source of claim 1, wherein: the discharging electrode I (3), the PEEK insulating ring I (4), the radio frequency electrode (5), the PEEK insulating ring II (6), the discharging electrode II (7), the ionization region (8) and the ion outlet (11) are located on the same axis.

4. The radio frequency discharge excited methylene chloride induced proton transfer reaction ion source of claim 1, wherein: the excited dichloromethane is generated by exciting dichloromethane by radio frequency discharge.

5. The radio frequency discharge excited methylene chloride induced proton transfer reaction ion source of claim 1, wherein: the molecules of the substance to be detected are ionized by proton transfer reaction induced by exciting dichloromethane.