CN115183152A - A kind of pump pumping and sampling ion mobility spectrometer control gas circuit - Google Patents

Abstract

The invention discloses a control gas circuit of a pumping gas injection type ion mobility spectrometer. The invention uses ion migration spectrum technology as basic detection technology, and when the analyzer works continuously, three gas flows of carrier gas, floating gas and chemical dopant are controlled and stabilized by variable diameter gas path pipe technology. The stable gas path system can be provided for the ion mobility spectrometer, and the rapid and high-sensitivity analysis and detection of the target sample can be realized. The gas path control technical method has the advantages of good sealing performance, simple and convenient installation and high reliability, and is suitable for providing a stable gas source for the ion mobility spectrometer.

Description

Control gas circuit of a pump pumping and sampling ion mobility spectrometer

technical field

The invention belongs to the field of research and development of analytical instruments, and in particular relates to a gas path control method for an ion mobility spectrometer analyzer for pumping air and sampling.

Background technique

Ion mobility spectrometry (IMS) is a separation and analysis technique of gas-phase ions in an electric field under atmospheric pressure. The ion transfer tube containing the ionization source is the core component of the IMS, which directly determines the sensitivity and measurable range of the IMS. Due to the potential danger of β-ray radiation from ⁶³ Ni sources in commercial IMS, non-radioactive ionization sources represented by photoionization technology have become a research hotspot in recent years.

New photoionization sources based on VUV lamps, reagent molecule-assisted ionization positive ion sources and negative ion sources are widely used. The developed negative ion mobility spectrum of reagent molecule-assisted photoionization can generate a new reactive reagent ion, which can ionize the target molecule with high efficiency and form characteristic product ion peaks. By changing the direction of gas flow in the ion mobility spectrum, rapid switching of reagent ions can be achieved. Acetone is the most commonly used auxiliary photoionization ion mobility spectrometry reagent molecule. Reagent molecules are usually added to the carrier gas or drift gas and enter the ion transfer tube with the sample.

Analyzers based on ion mobility spectrometry work under atmospheric pressure conditions and require a clean gas source for normal operation. Generally, ion mobility spectrometers include a carrier gas inlet, a drift gas inlet, and a gas outlet. The new generation of ion transfer tube is divided into four through holes to connect the gas pipeline, and the gas flow of each channel needs to be controlled. At least 3 gas flow controllers are required, which are not only expensive, but also relatively large and heavy, adding many difficulties to product structure design, product certification and market application. The present invention solves this technical problem.

The thermal desorption sampler ion mobility spectrum gas circuit (patent number ZL201210508587.8) invented by Cang Huaiwen et al. discloses that the ion mobility spectrum gas circuit circulation system has basic functions such as detection, standby, and backflushing, which can prolong purification agent service life. The ion mobility spectrometer gas circuit has more working states and has a wider range of applications. Although this patent introduces an ion mobility spectrometer gas circuit circulation system. However, the flow of the gas still needs to be controlled by a flow meter, which increases the cost of the product and the stability of the gas flow is not ideal.

An analyzer control gas circuit for ion mobility spectrometer technology invented by Wang Xin et al. (Patent No. ZL201911136713.X), which uses ion mobility During cleaning, the flow and direction of the carrier gas and the rinsing gas are alternately changed in three ways. The final stable carrier gas and drift gas flow and flow control method can reduce system pollution and facilitate accurate and sensitive quantification of target samples. However, the gas flow of the carrier gas and the drift gas still needs to be controlled separately by the flowmeter, which increases the cost and weight, which is not conducive to the requirement of product certification.

SUMMARY OF THE INVENTION

The invention takes the ion mobility spectrometry technology as the basic detection technology. When the analyzer works continuously, the three-way gas flow of the carrier gas, the drift gas and the chemical dopant dopant gas is controlled and stabilized by the variable diameter gas pipe technology; The mobility spectrometer provides a stable gas circuit system, which can achieve rapid and highly sensitive analysis and detection of target samples. The gas circuit control method can reduce the number of gas flow controllers, and the gas circuit is stable and stable; stable reagent ion peak signal It is beneficial to the accurate and sensitive quantification of ion mobility spectrometer. The gas path control technical method of the invention has the advantages of good sealing, simple installation and high reliability, and is suitable for providing a stable gas source for the ion mobility spectrometer

Specifically, the following technical solutions are adopted:

An ion mobility spectrometer controlling gas path for pumping and sampling, wherein the ion mobility spectrometer has 4 through holes on the outer wall of its ion migration tube, and one of the through holes is the air outlet of the ion migration tube , the remaining three through holes are gas inlets, that is, the four through holes are the gas outlet of the ion transfer tube, the inlet of the dopant carrier gas, the inlet of the sample carrier gas, and the inlet of the drift gas; the total gas source output from the gas outlet of the ion transfer tube is The sample carrier gas, the dopant carrier gas and the drift gas are collected in three ways;

The air passage terminal of the air outlet of the ion migration tube is pumped by an air pump, and a gas flow controller is connected between the air pump and the air outlet of the ion migration tube to control the total flow of outflow gas;

The gas source is connected with the inlet end of the three-way joint through the gas restrictor valve, and the outlet end of the three-way joint is respectively connected with the two-way joint II and the two-way joint I, and the two-way joint II is connected with the drift gas inlet of the ion transfer tube, so the The two-way joint I is connected to the dopant carrier gas inlet of the ion transfer tube through the dopant cartridge II; the dopant carrier gas and the drift gas are supplied by the ion transfer tube analyzer externally from the clean gas source through the gas restrictor valve to provide total. The gas is divided into two paths of dopant carrier gas and drift gas respectively by the three-way joint. The three-way joint and the two-way joint I, and the three-way joint and the two-way joint II are respectively divided into dopants by connecting pipes with different inner diameters. There are two paths of carrier gas and drift gas; one of the drift gases is connected to the two-way connector II, and enters the ion transfer tube through the drift gas inlet; The dopant carrier gas inlet (2) enters the ion transfer tube. The split ratio of dopant carrier gas and drift gas flow is achieved by changing the length and inner diameter of the gas flow pipe between the two-way joints. The two-way joints are respectively reduced diameter two-way.

The sample carrier gas inlet is sequentially connected to the sampler, the dopant cartridge II, the air purification tube, and the air purification tube is provided with a through hole communicating with the outside world, and a carrier gas source can flow in the through hole.

Based on the above technical solutions, preferably, the control gas path is the pump sampling mode, the pumping flow rate is controlled at 500-1000sccm, and the gas flow controller is used to control the gas flow and voltage stabilization.

Based on the above technical solutions, preferably, the ion transfer tube has good sealing performance and can withstand air pressure up to 0.2MPa.

Based on the above technical solutions, preferably, the sample carrier gas flow is the difference between the pumping flow rate and the sum of the dopant carrier gas and the rinse gas flow.

Based on the above technical solutions, preferably, the gas flow direction in the ion transfer tube is a unidirectional gas flow mode, and the sample carrier gas, dopant carrier gas and drift gas are integrated into one channel, flow in one direction toward the gas outlet, and flow out through the gas outlet. .

Based on the above technical solutions, preferably, the flow rates of the dopant carrier gas and the drift gas are limited by the gas restrictor valve to limit the total gas flow, and then divided into two paths of the dopant carrier gas and the drift gas by the three-way joint, and the dopant carrier gas Connect with the two-way joint I through the gas path connecting pipe I, and the drift gas passes through the gas path connecting pipe II and the two-way joint II. , The length and inner diameter of the gas path connecting pipe II between the three-way joint and the two-way joint II are realized.

Based on the above technical solutions, preferably, the length of the gas path connecting pipe I and the gas path connecting pipe II is 5-20 cm, and the inner diameter is 0.5-3 mm.

Based on the above technical solutions, preferably, the flow rate of the drift gas is 400-600 sccm, the flow rate of the sample carrier gas is 50-400 sccm, and the flow rate of the drift gas is greater than the flow rate of the sample carrier gas.

Based on the above technical solutions, preferably, there are two dopant cartridges, which are respectively connected to the carrier gas path and a separate path, which can increase the ion concentration of the photoionization reagent and enhance the dual effects of ionization and desorption.

Based on the above technical solutions, preferably, all gas paths are purified by molecular sieve and activated carbon.

The ion mobility spectrum analyzer in the present invention controls the gas path method, and the two-path variable-diameter gas path pipe replaces the two mass flow meters, which is simple and easy to implement, has better practical effects and has a wide range of applications.

Advantages of the present invention

(1) The pump pumping and sampling gas path of the analyzer replaces the gentle carrier gas purging and sampling gas path mode, and the thermal desorption efficiency of the detected sample is high, which can improve the detection sensitivity of the target object.

(2) In the ion mobility spectrometer of the present invention, the dopant carrier gas and the drift gas flow do not use a gas flow controller to control the gas flow, and the total gas flow is controlled by the split flow according to the split ratio. The specific implementation method is changed by changing the dopant The length and inner diameter of the carrier and drift gas lines are achieved.

(3) In the ion mobility spectrometer of the present invention, the dopant gas is added to the two gas paths, which is not only conducive to stably controlling the ion signal intensity of the photoionization reagent, but also helps to improve the ionization efficiency of the sample in the ionization zone.

Description of drawings

Fig. 1 is the schematic diagram of gas circuit control of ion mobility spectrometer in the present invention;

Fig. 2 is the air reagent ion peak that gas circuit obtains according to embodiment 1 in the present invention;

Among them: 1 is the gas outlet of the ion transfer tube, 2 is the dopant carrier gas inlet, 3 is the sample carrier gas inlet, 4 is the gas flow controller, 5 is the air pump, 6 is the sampler device, and 7 is the dopant Tubes I and 8 are air purification pipes, 9 is a gas restrictor valve, 10 is a three-way joint, 11 is a dopant tube II, 12 is a two-way joint I, 13 is a two-way joint II, and 14 is a float inlet.

Fig. 3 is the ion mobility spectrogram of propofol in 5ng/μL blood detected by the gas path of the ion mobility spectrometer in the present invention;

Figure 4 shows the ion mobility spectrum of propofol in 5ng/μL blood detected by the carrier gas purging gas path.

Detailed ways

The ion mobility spectrometry device in the present invention mainly includes the following parts: a sampler device, an ion transfer tube, two chemical dopant devices (a dopant cartridge I7 and a dopant cartridge II11), a gas source device and a gas source device. Road connecting pipe and signal receiving and processing system. The control gas path connection method in the present invention is shown in Figure 1 .

An ion mobility spectrometer for pumping and sampling is provided to control the gas path. The ion mobility spectrometer has 4 through holes on the outer wall of the ion migration tube, and one of the through holes is the air outlet of the ion migration tube. The remaining three through holes are all gas inlets, that is, the four through holes are the ion transfer tube gas outlet 1, the dopant carrier gas inlet 2, the sample carrier gas inlet 3, and the drift gas inlet 14; the ion transfer tube gas outlet 1 outputs The total gas source is composed of sample carrier gas, dopant carrier gas and drift gas;

The air passage terminal of the air outlet of the ion transfer tube is pumped by an air pump, and a gas flow controller 4 is connected between the air pump 5 and the air outlet 1 of the ion transfer tube to control the total flow of outflow gas;

The dopant carrier gas and the drift gas are supplied by the ion mobility spectrometer externally to the clean gas source through the gas restrictor valve 9 to provide the total gas, and then split into two paths of the dopant carrier gas and the drift gas by the three-way joint 10 respectively. The joint 10 and the two-way joint I12, the three-way joint 10 and the two-way joint II13 are respectively divided into two gas paths of the dopant carrier gas and the drift gas through the gas path connecting pipes with different inner diameters; The gas inlet 14 enters the ion transfer tube; the other dopant carrier gas is connected to the two-way joint 12, connected to the dopant cartridge II11, and then enters the ion transfer tube. The split ratio of dopant carrier gas and drift gas flow is achieved by changing the length and inner diameter of the gas flow pipe between the two-way joints. The two-way joint I12 and the two-way joint II13 are respectively diameter reducing two-way.

The sample carrier gas inlet 3 is connected to the sample injector 6, the dopant cartridge 17, the air purification pipe 8, and the air purification pipe 8 in sequence, and is provided with a through hole communicating with the outside world, and a carrier gas source can flow in the through hole.

The control gas circuit is the pump sampling and sampling mode, the gas flow rate is controlled at 500-1000sccm, and the gas flow controller (4) controls the gas flow and the voltage stabilization.

The ion transfer tube has good sealing performance and can withstand air pressure up to 0.2MPa.

Inject carrier gas flow, the difference between the flow rate of the pumped gas and the sum of the dopant carrier gas and the rinse gas flow.

The gas flow in the ion transfer tube is a unidirectional gas flow mode. The sample carrier gas, the dopant carrier gas and the drift gas are integrated into one channel, which flows in one direction towards the gas outlet and flows out through the gas outlet.

The flow rate of the dopant carrier gas and the bleed gas is limited by the gas restrictor valve 9 to limit the total flow, and then divided into two paths by the tee joint (10) into the dopant carrier gas and the bleed gas, and the dopant carrier gas is connected through the gas path The pipe I is connected with the two-way joint I12, and the floating gas passes through the gas path connecting pipe II and the two-way joint II13. The split ratio of the gas flow is changed by changing the gas path connecting pipe I, the three-way connection between the three-way joint 10 and the two-way joint I12. The length and inner diameter of the gas path connecting pipe II between the joint 10 and the two-way joint II13 are realized.

The length of the gas path connecting pipe I and the gas path connecting pipe II is 5-20cm, and the inner diameter is 0.5-3mm.

The flow rate of the drift gas is 400-600 sccm, the flow rate of the sample carrier gas is 50-400 sccm, and the flow rate of the drift gas is greater than the flow rate of the carrier gas.

There are 2 dopant cartridges, which are respectively connected to the carrier gas path and a separate path, which can increase the ion concentration of the photoionization reagent and enhance the dual effects of ionization and desorption.

All gas paths are purified by molecular sieve and activated carbon.

Example 1

The ion mobility spectrometer is set with uniform parameters: the temperature of the migration tube is 100 ℃, the sampler is 150 ℃; the gas source is the purified air source, the control flow rate of the drift gas is 600sccm, the control flow rate of the dopant carrier gas is 50sccm, and the pump The pumping control flow rate is 1000sccm, the air connection pipe I is a φ2 (inner diameter 1mm), 10cm long air transmission pipe, and the air connection pipe II is a φ4 (inner diameter 2.5mm), 10cm long air transmission pipe, the air source passes through The 10-point tee joint is divided into two gas paths of dopant carrier gas and drift gas; the ion gate opening time is 50μs, and the average number of times is 20; two channels of acetone are used as dopant reagent ions, and the acetone dopant gas is connected to the carrier gas and a separate channel respectively. in the air path.

Connect each component of the instrument according to the control gas circuit in Figure 1 of the present invention, and record the negative high pressure mode acetone air reagent ion peak as shown in Figure 2. The signal intensity of acetone air reagent ion peak (CO ₄ ^- ) reached 5000mv.

Example 2

The ion mobility spectrometer is set with uniform parameters: the temperature of the migration tube is 100 ℃, the sampler is 150 ℃; the gas source is the purified air source, the control flow rate of the drift gas is 600sccm, the control flow rate of the dopant carrier gas is 50sccm, and the pump The pumping control flow rate is 1000sccm, the air connection pipe I is a φ2 (inner diameter 1mm), 10cm long air transmission pipe, and the air connection pipe II is a φ4 (inner diameter 2.5mm), 10cm long air transmission pipe, the air source passes through The 10-point tee joint is divided into two gas paths of dopant carrier gas and drift gas; the ion gate opening time is 50μs, and the average number of times is 20; two channels of acetone are used as dopant reagent ions, and the acetone dopant gas is connected to the carrier gas and a separate channel respectively. in the air path.

Connect each component of the instrument according to the control gas circuit in Figure 1 of the present invention, take a 10 μL, 5ng/μL blood propofol sample, record the thermal desorption curve of propofol, and the ion mobility spectrum peaks are shown in Figure 3. A single analysis The detection time was 2 min, and the thermal desorption curve signal was stable.

Change the gas path to non-pump pumping, carrier gas purging and sampling mode (invention patent No. ZL201911136713.X, an ion mobility spectrum control gas path), the drift gas control flow rate is 600sccm, the dopant carrier gas control flow rate is 50sccm, and the sample The carrier gas was 350 sccm, 10 μL and 5 ng/μL blood propofol samples were taken, and the thermal desorption ion mobility spectrum peaks of propofol were recorded. No propofol was detected as shown in Figure 4. It is obvious that the gas path mode is different, and under the same gas flow rate, the pumping and sampling method enhances the detection sensitivity of propofol.

Example 3

The selected air source is the purified air source, the restrictor valve controls the total air flow of 1000sccm, and when the air pressure is regulated to 0.1MPa, the air path connecting pipe I and the air path connecting pipe II after the three-way split are all made of φ4 (inner diameter 2.5mm). ), 5cm long air pipe, measure the output air pressure of air connection pipe I and air connection pipe II to be equal and unchanged, and the air flow is divided into two equal paths of 500sccm each. If the air connection pipe I and the air connection pipe II after the three-way shunt are both made of φ4 (inner diameter 2.5mm) and 20cm long air pipes, measure the output air pressures of the air connection pipe I and the air connection pipe II are equal and not equal to each other. Change, the air flow is divided into two equal paths of 500sccm each.

Example 4

The selected air source is the purified air source, the restrictor valve controls the total airflow of 1000sccm, and when the air pressure is regulated to 0.2MPa, the air path connecting pipe I after the three-way shunt is φ1 (inner diameter 1mm), 20cm long air path pipe , the gas path connecting pipe II is φ4 (inner diameter 2.5mm), 20cm long gas path pipe, measure the gas path connecting pipe I output stable airflow 50sccm, the gas path connecting pipe II output stable airflow 950sccm.

Claims (9)

1. A pump pumping and sampling ion mobility spectrometer control gas path, it is characterized in that: described ion mobility spectrometer, the outer wall surface of its ion migration tube is provided with ion migration tube air outlet (1), mixed with The dopant carrier gas inlet (2), the sample carrier gas inlet (3), and the bleach gas inlet (14); the ion transfer tube gas outlet (1) outputs the total gas source from the sample carrier gas, the dopant carrier gas and the bleach gas. a collection of roads; The air path terminal of the air outlet of the ion transfer tube is pumped by an air pump, and a gas flow controller (4) is connected between the air pump (5) and the air outlet (1) of the ion transfer tube, for controlling the total flow of the outflow gas; The gas source is connected to the inlet end of the tee joint (10) through the gas restrictor valve (9), and the outlet end of the tee joint (10) is respectively connected to the two-way joint II (13) and the two-way joint I (12), so The two-way joint II (13) is connected to the drift gas inlet (14) of the ion transfer tube, and the two-way joint I (12) passes through the dopant cartridge II (11) and the dopant carrier gas inlet (14) of the ion transfer tube. 2) Connection; the gas source is divided into two paths of dopant carrier gas and drift gas through the gas restrictor valve (9) and the tee joint (10), and the drift gas path passes through the two-way joint II (13) and the drift gas inlet. (14) entering the ion transfer tube; the dopant carrier gas gas path enters the ion transfer tube through the two-way joint I (12), the dopant barrel II (11), and the dopant carrier gas inlet (2); The sample carrier gas inlet (3) is connected to the sample injector (6), the dopant cartridge 1 (7), and the air purification pipe (8) in turn, and the air purification pipe (8) is provided with a through hole communicating with the outside world, A carrier gas source can flow through the through hole. 2 . The control air circuit according to claim 1 , wherein the control air circuit is a pump pumping and sampling mode, and the pumping flow rate is controlled at 500-1000 sccm. 3 . 3. The control gas circuit according to claim 1 or 2, wherein the air pressure resistance of the ion transfer tube can reach 0.2MPa. 4 . The control gas circuit according to claim 1 , wherein the sample carrier gas flow is the difference between the pumping gas flow rate and the sum of the dopant carrier gas and the drift gas flow. 5 . 5. The control gas circuit according to claim 1 is characterized in that: the gas flow direction in the ion transfer tube is a unidirectional gas flow mode, and the three paths of sample carrier gas, dopant carrier gas and drift gas are integrated into one, and the direction of the gas outlet is from the direction of the gas outlet. outflow. 6. The control gas circuit according to claim 1 is characterized in that: the flow rate of the dopant carrier gas and the drift gas is limited by the gas restrictor valve (9) to limit the total gas flow, and then divided by the three-way joint (10) into a mixed gas flow. The dopant carrier gas and the bleed gas have two paths, and the split ratio of the gas flow of the dopant carrier gas and the bleed gas is changed by changing the gas path connecting pipes I, 3 The length and inner diameter of the gas path connecting pipe II between the through joint (10) and the two-way joint II (13) are realized. 7. The control gas path according to claim 6, wherein the length of the gas path connecting pipe I and the gas path connecting pipe II is 5-20cm, and the inner diameter is 0.5-3mm. 8 . The control gas circuit according to claim 1 , wherein the flow rate of the drift gas is 400-600 sccm, the flow rate of the sample carrier gas is 50-400 sccm, and the flow rate of the drift gas is greater than the flow rate of the sample carrier gas. 9 . 9 . The control gas circuit according to claim 1 , wherein the gas in all the gas circuits is purified by molecular sieve and activated carbon before use, and the relative humidity of the gas is less than 1%. 10 .

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