1. The in-situ thermal desorption photoionization device for improving the sensitivity of mass spectrometry for detecting drugs comprises a metal heating block (2), a peek material heat preservation shell (3), a radio frequency lamp tetrafluoro sleeve (4), a radio frequency lamp (5), a sample injection metal capillary tube (6), an air inlet pipe (7), a peek material carrier gas inlet (8) and a motor top head (9);

the left side and the right side of the metal heating block (2) are respectively provided with two grooves to form two hollow cavities which are respectively used as an ionization cavity and a thermal desorption cavity, and a through hole is arranged between the two cavities; a peek material heat preservation shell (3) is arranged outside the metal heating block (2);

a through hole for accommodating a radio frequency lamp tetrafluoro sleeve (4) and a radio frequency lamp (5) is formed in the left side of the heat preservation shell (3), the radio frequency lamp (5) is arranged at the opening end of the left side of the ionization cavity, emergent light of the radio frequency lamp (5) is emitted into the ionization cavity towards the ionization cavity, and the radio frequency lamp (5) is sleeved in the tubular radio frequency lamp tetrafluoro sleeve (4) in a penetrating manner;

a through hole for accommodating a motor top head (9) is formed in the right side of the heat preservation shell (3), the motor top head (9) is arranged at the right side opening end of the thermal desorption cavity, and the motor top head (9) can reciprocate left and right at the right side opening end of the thermal desorption cavity through the motor drive;

one open end of the sample injection metal capillary (6) penetrates through the heat preservation shell (3) and extends into the ionization cavity, and a sample obtained by thermal desorption is guided into a detection instrument connected with the other open end of the sample injection metal capillary (6); a through hole is formed in the side wall of the thermal desorption cavity, and one end of the air inlet pipe (7) is hermetically connected with one end, far away from the thermal desorption cavity, of the through hole;

a carrier gas through hole is arranged on the side wall surface of the heat preservation shell (3), a peek material carrier gas inlet (8) joint is accommodated in the opening end of the through hole, which is far away from the metal heating block (2), and the other opening end of the through hole is hermetically connected with the other end of the air inlet pipe (7);

a through hole for inserting and pulling out the sampling cloth (1) is arranged on the side wall surface of the heat preservation shell (3), the sampling cloth (1) can be inserted into the right opening end of the thermal desorption cavity through the through hole and can be abutted against the right opening end of the thermal desorption cavity through a motor top head (9) at the right end of the sampling cloth, and a sample on the sampling cloth is inserted into the in-situ thermal desorption photoionization device through the sampling cloth (1) of the tetrafluoro;

an electric heating element is arranged inside the heating block (2).

2. The apparatus of claim 1, wherein: in the in-situ thermal desorption photoionization device, an electric heating rod is embedded in a stainless steel metal heating block (2) in advance, the surface of the metal block can be heated within 1 minute and is kept at the constant temperature of 180 ℃, a sample on tetrafluoro sampling cloth (1) inserted into the device can be instantaneously desorbed under the action of heat radiation of the metal block, but the traditional open system can cause the fluctuation of the surface temperature of the metal heating block, and the thermal desorption efficiency of the sample is influenced;

the Peek material heat-insulating shell (3) and the Peek material carrier gas inlet (8) are used for reducing heat loss of the device, so that the power consumption of the instrument is reduced; the radio frequency lamp tetrafluoro sleeve (4) is used for protecting a radio frequency lamp (5), fixing the radio frequency lamp and simultaneously preventing a lamp window of the radio frequency lamp from directly contacting a stainless steel metal heating block (2) so as to prevent the ionization efficiency of the radio frequency lamp from being influenced when the temperature changes, the right opening end of the radio frequency lamp tetrafluoro sleeve (4) is abutted with the metal heating block (2) around the left opening end of an ionization cavity, and a gap is reserved between the lamp window of the radio frequency lamp and the metal heating block (2) around the left opening end of the ionization cavity;

the radio frequency lamp is an ionization source loaded with alternating current, can emit photoelectrons with specific energy under normal pressure, can directly photoionize some gaseous neutral molecules, and greatly simplifies the structure of the ionization source device; in the in-situ thermal desorption photoionization device, the light beam of a radio frequency lamp can directly irradiate into a stainless steel metal block to ionize a sample in the stainless steel metal block;

the stainless steel air inlet pipe (7) is connected to the metal heating block (2), so that air or other auxiliary gas (such as nitrogen) can be fed into the metal heating block, the inside of the device can be quickly cleaned, and the residue of the device is reduced; the Peek material inlet (8) is used for reducing heat loss so as to isolate the inner metal material from the outer Peek material;

the sample is loaded on the PTFE sampling cloth (1), when the sampling cloth is inserted into the device, the motor top head (9) moves leftwards under the action of the transmission device to jack the PTFE sampling cloth to contact the stainless steel metal heating block (2), so that high-temperature thermal analysis is started.

3. The apparatus of claim 1, wherein:

the stainless steel metal heating block (2) is internally provided with two cylindrical hollow cavities which are respectively positioned on the left side and the right side of the heating block and respectively serve as an ionization cavity and a thermal desorption cavity. A section of metal with a through hole is arranged between the two cavities at intervals, the diameter of the through hole is 2mm, and the thickness of the through hole is 1 mm. The ionization cavity on the left side is a hollow cylindrical cavity with the diameter of 6mm and the depth of 4mm, the thermal desorption cavity on the right side is also a cylindrical hollow cavity with the diameter of 5mm and the depth of 3mm, and the two cavities are connected through a through hole;

the outer surface of the left side of the metal heating block is contacted with a tetrafluoro sleeve (4) of the radio frequency lamp; when the motor top head (9) moves leftwards, the tetrafluoro sampling cloth inserted into the device is jacked up, so that one surface of the tetrafluoro sampling cloth is contacted with the outer surface of the right side of the stainless steel metal heating block.

4. The apparatus of claim 1, wherein:

the peek material heat-insulating shell (3) and the peek material carrier gas inlet (8) are used for reducing heat loss of the device, so that temperature fluctuation of the surface of the metal block is reduced; the Peek material carrier gas inlet can introduce air, other auxiliary reagent gases or gas to be detected into the device, the inner diameter of the Peek material gas inlet is 3mm, and the Peek material is in non-contact with the stainless steel gas inlet pipe (7), so that the heat loss inside the device is further reduced, and the thermal analysis and detection of a sample are facilitated.

5. The apparatus of claim 1, wherein:

the radio frequency lamp is an ionization source loaded with alternating current, can emit photoelectrons with specific energy under normal pressure, can directly photoionize gasified neutral molecules, and greatly simplifies the structure of the ionization source device; in the in-situ thermal desorption photoionization device, the light beam of a radio frequency lamp can directly irradiate into an ionization cavity at the left side of a stainless steel heating block (2), so that a gaseous sample in the ionization cavity is ionized; the diameter of an optical window of the radio frequency lamp is 11mm, and the outer surface of the optical window is contacted with a tetrafluoro sleeve (4) of the radio frequency lamp.

6. The apparatus of claim 1, wherein:

the stainless steel air inlet pipe (7) is a through-hole screw with the inner diameter of 2mm and the outer surface of M3 threads, and can be directly screwed on the stainless steel metal heating block (2); the gas entering from the peek material carrier gas inlet (8) can be further sent into the thermal desorption cavity on the right side of the stainless steel metal heating block (2) through a stainless steel gas inlet pipe (7).

7. The apparatus of claim 1 or 3, wherein:

the sample injection metal capillary (6) is a metal capillary with the inner diameter of 0.02 inch and the outer diameter of 1/16 inches; the sample injection metal capillary (6) extends into the metal heating block and is used for sending ions in the ionization cavity on the left side of the stainless steel metal heating block (2) into a detection instrument at the rear end, and one end of the metal capillary is tangent to the side surface of the ionization cavity; because the metal capillary tube extends into the stainless steel metal heating block, the metal capillary tube can also maintain a certain high temperature, thereby being beneficial to reducing the loss of samples.

8. The apparatus of claim 1, wherein:

the working sequence of the device is that a sample is loaded on a tetrafluoro sampling cloth (1) firstly, when the sampling cloth is inserted into the device, a motor top head (9) moves leftwards under the action of a transmission device to jack the tetrafluoro sampling cloth and contacts a stainless steel metal heating block (2), the sample is heated instantaneously to be analyzed into gas, and high-temperature gas is diffused into an ionization cavity on the left side of the stainless steel metal heating block from a thermal desorption pool immediately; because the inside of the device is always kept at a constant high temperature, the sample is hardly remained to cause loss, the sample in the ionization cavity is ionized into ions under the irradiation of the radio frequency lamp and stays in the ionization cavity for a short time, and at the moment, a detection instrument at the rear end can extract the ions in the ionization cavity for analysis and detection. After the analysis and detection are finished, the peek material carrier gas inlet (8) can be introduced into the clean gas cleaning device, so that the residue is further reduced.

Background

The analysis method of in situ thermal desorption is approved, is widely applied to real-time monitoring of easily degradable substances in soil or other complex matrixes, and is favorable for accurately obtaining required field data. The thermal analysis sample has the advantages of high speed, simple structure, high efficiency and the like, and is the most common method before the atmospheric pressure ionization source ionizes the gaseous sample at present. This is because the gaseous sample molecules have higher ionization efficiency than the solvation in the solid and liquid states, which has a great intermolecular interaction, and are suitable for various atmospheric pressure chemical ionization sources developed at present, but it is greatly affected by the thermal desorption temperature and the temperature rise rate, and it is difficult to detect the volatile sample when the temperature is insufficient. Hou Coroyong et al use special refrigeration to enrich volatile organic compounds in the atmosphere in the adsorption tube, directly heat the adsorption tube for rapid thermal analysis, and then directly enter a gas chromatograph with carrier gas for separation and analysis without a secondary cold trap or a secondary concentration patent (201711252056.6). VINEGAR HAROLD et al utilize an in situ thermal desorption method to remove or reduce contamination within the soil, heat being transferred to the soil by bare metal heater elements heated by electrical resistance. The heater element is disposed directly within the soil. (us. patent 6632047) Kunkel et al used a specially designed heat trap to heat the soil in situ to 500 c to remove the hard volatile contaminants and heavy metal elements such as mercury from the soil.

The drugs have various types, and the difference of molecular weight and polarity causes the difference of volatility, for example, the boiling point of fentanyl type new psychoactive drugs is generally over 500 ℃, and the boiling point of methamphetamine, K powder, heroin and the like is about 300 ℃. At present, the components of emerging psychotropic drugs and plant samples are very complex, the number of the emerging psychotropic drugs controlled by China is as much as 170, and the detection sensitivity is lower when the traditional continuous purging and metal contact type temperature rising thermal analysis are used for analyzing the hard-to-volatilize and volatile drug mixed samples. The main reasons are: 1) the low-content drug components are often missed to be detected due to the low signal-to-noise ratio of the instrument, and due to the low duty ratio, part of the sample can be brought out of an ionization region by continuously blown gas and cannot be detected; 2) the low-volatility drugs have low vaporization efficiency and poorer detection sensitivity when the temperature rise speed is not high enough or the temperature is not high enough due to low saturated vapor pressure; 3) loss of gaseous drug sample during sample transport.

In current mass spectrometer instrument designs, the thermal analysis region and the ionization region are not together to avoid residual contamination of the thermal analysis sample, and the transport of a carrier gas is required for the sample to enter the ionization chamber from the thermal analysis region. Continuous purging has certain diffusion effect and delay effect when passing through a channel with a large pipe diameter, so that the detection signal is reduced, the sample is remained, and the peak broadening is aggravated.

Therefore, the invention designs an in-situ thermal desorption photoionization device for improving the on-site detection sensitivity of drugs. The drugs are rapidly heated and volatilized from the room temperature, and high-temperature gas can be immediately diffused into the ionization cavity on the left side of the stainless steel metal heating block from the thermal desorption pool. Because the inside of the device is always kept at a constant high temperature, the sample is hardly remained to cause loss, the sample in the ionization cavity is ionized into ions under the irradiation of the radio frequency lamp and stays in the ionization cavity for a short time, and at the moment, a detection instrument at the rear end can extract the ions in the ionization cavity for analysis and detection. After the analysis and detection are finished, the peek material carrier gas inlet (8) can be introduced into the clean gas cleaning device, so that the residue is further reduced. The advantage of structure like this has reduced the sample detection loss that causes because instrument SNR is low etc. under the sampling mode of sweeping in succession to improve the sample utilization ratio, the signal intensity of sample is compared with the intensity that sweeps the accumulation in succession of the same time and has been improved an order of magnitude.

Disclosure of Invention

The invention aims to provide an analysis device for solving the problem of high-sensitivity detection of drugs.

In order to achieve the purpose, the invention adopts the technical scheme that:

the main structural parts of the in-situ thermal desorption photoionization device comprise a stainless steel metal heating block, a peek material heat preservation shell, a radio frequency lamp tetrafluoro sleeve, a radio frequency lamp, a stainless steel air inlet pipe, a peek material carrier gas inlet and a motor top, wherein a sample is inserted into the device through a tetrafluoro sampling cloth, and the thermally-desorbed sample is introduced into a rear-end detection instrument through a sample injection metal capillary.

In the in-situ thermal desorption photoionization device, a stainless steel metal heating block is a special-shaped metal block which is machined through a series of machines, a heating rod is embedded in the stainless steel metal heating block in advance, the stainless steel metal heating block can be heated in a short time and is kept at the constant temperature of 180 ℃, and a sample on tetrafluoro sampling cloth inserted into the device can be instantly analyzed under the action of heat radiation of the metal block. The Peek material heat preservation shell and the Peek material carrier gas inlet are used for reducing heat loss of the device, so that the power consumption of the instrument is reduced. .

The radio frequency lamp is an ionization source loaded with alternating current, can emit photoelectrons with specific energy under normal pressure, can directly photoionize some gaseous neutral molecules, and greatly simplifies the structure of the ionization source device. In an in situ thermal desorption photoionization device, a beam of a radio frequency lamp may be directed into a stainless steel metal block to ionize a sample therein.

Stainless steel intake-tube connection can send air or other supplementary gas into metal heating piece on the metal heating piece, can be used for quick cleaning device's inside, reduces the residue of device. The use of the Peek material air inlets is to reduce heat loss, thereby isolating the inner metal material from the outer Peek material.

The sample is loaded on the PTFE sampling cloth, when the sampling cloth is inserted into the device, the motor top head moves leftwards under the action of the transmission device to jack the PTFE sampling cloth to contact the stainless steel metal heating block, so that high-temperature thermal analysis is started.

Two cylindrical hollow cavities are arranged in the stainless steel metal heating block and are respectively positioned on the left side and the right side of the heating block, and the stainless steel metal heating block and the heating block are respectively used as an ionization cavity and a thermal desorption cavity. A section of metal with a through hole and a certain thickness is arranged between the two cavities

The Peek material carrier gas inlet can introduce air, other auxiliary reagent gases or gas to be detected into the device, and the Peek material is not in contact with the stainless steel gas inlet pipe, so that the internal heat loss is further reduced, and the thermal analysis and detection of the sample are facilitated.

The stainless steel air inlet pipe can be directly screwed on the stainless steel metal heating block. The gas entering from the peek material carrier gas inlet can be further sent into the thermal desorption cavity on the right side of the stainless steel metal heating block through the stainless steel gas inlet pipe.

The sample injection metal capillary tube extends into the metal heating block and is used for sending ions in the ionization cavity on the left side of the stainless steel metal heating block into a detection instrument at the rear end. Because the metal capillary tube extends into the stainless steel metal heating block, the metal capillary tube can also maintain a certain high temperature, thereby being beneficial to reducing the loss of samples.

The working time sequence of the device is that a sample is loaded on the tetrafluoro sampling cloth firstly, when the sampling cloth is inserted into the device, the motor top head moves leftwards under the action of the transmission device to jack the tetrafluoro sampling cloth up to contact with the stainless steel metal heating block, the sample is instantaneously heated and analyzed into gas, and the high-temperature gas can be immediately diffused into the ionization cavity on the left side of the stainless steel metal heating block from the thermal desorption pool. Because the inside of the device is always kept at a constant high temperature, the sample is hardly remained to cause loss, the sample in the ionization cavity is ionized into ions under the irradiation of the radio frequency lamp and stays in the ionization cavity for a short time, and at the moment, a detection instrument at the rear end can extract the ions in the ionization cavity for analysis and detection. After the analysis and detection are finished, the carrier gas inlet of the peek material can be introduced into the clean gas cleaning device, so that the residue is further reduced;

the types of drugs are numerous, the difference of boiling points is large, and common smuggling drugs have various drugs which are difficult to volatilize and easy to volatilize, so that the sensitivity of an instrument taking a vapor phase as a detection object is seriously influenced by the temperature of thermal desorption, the heating rate and the sample transmission efficiency, and therefore, the in-situ thermal desorption photoionization source device is designed to improve the drug detection sensitivity of mass spectrometry. The main principle of the device is that the sample subjected to thermal desorption is directly sucked into the mass analyzer by utilizing the vacuum of the mass spectrum, so that the loss in the transmission process in a sample space is reduced, meanwhile, the in-situ thermal desorption is realized, the space density of the desorption sample is improved, the high temperature of the desorption pool is also improved, the thermal desorption pool is rapidly heated to heat the drugs, the sample can be heated to more than 150 ℃ within 2s, and more ions can be ionized under the action of the radio frequency lamp. The in-situ thermal desorption photoionization source device is used, the temperature rising speed is high, sample residue is small, the device is greatly simplified compared with the traditional desorption and sample introduction split type structure, the gas consumption is reduced, the heating power consumption of the device is small, and the requirement of a field portable analysis device is met.

The invention has the advantages that:

the invention reduces the loss of the sample from thermal analysis to sample introduction, improves the sensitivity of the instrument for detecting the sample by using thermal analysis, and has simple structure and drug detection sensitivity reaching 10 pg.

Drawings

FIG. 1 is a cross-sectional view of an in-situ thermal desorption apparatus.

FIG. 2 is a mass spectrum of 100pg papaverine and 100pg AM-2201(CAS NO:335161-24-5) detected using an in situ thermal desorption apparatus.

Detailed Description

As shown in fig. 1, the main structural parts of the in-situ thermal desorption photoionization device comprise a stainless steel metal heating block, a peek material heat preservation shell, a radio frequency lamp tetrafluoro sleeve, a radio frequency lamp, a stainless steel air inlet pipe, a peek material carrier gas inlet and a motor top, wherein a sample is inserted into the device through a tetrafluoro sampling cloth, and the sample subjected to thermal desorption is introduced into a rear-end detection instrument through a sample introduction metal capillary.

In the in-situ thermal desorption photoionization device, a stainless steel metal heating block is a special-shaped metal block which is machined through a series of machines, a heating rod is embedded in the stainless steel metal heating block in advance, the stainless steel metal heating block can be heated in a short time and is kept at the constant temperature of 180 ℃, and a sample on tetrafluoro sampling cloth inserted into the device can be instantly analyzed under the action of heat radiation of the metal block. The radio frequency lamp is an ionization source loaded with alternating current, can emit photoelectrons with specific energy under normal pressure, can directly photoionize some gaseous neutral molecules, and greatly simplifies the structure of the ionization source device. In an in situ thermal desorption photoionization device, a beam of a radio frequency lamp may be directed into a stainless steel metal block to ionize a sample therein.

Stainless steel intake-tube connection can send air or other supplementary gas into metal heating piece on the metal heating piece, can be used for quick cleaning device's inside, reduces the residue of device.

The sample is loaded on the PTFE sampling cloth, when the sampling cloth is inserted into the device, the motor top head moves leftwards under the action of the transmission device to jack the PTFE sampling cloth to contact the stainless steel metal heating block, so that high-temperature thermal analysis is started.

The Peek material carrier gas inlet may introduce air, other auxiliary reagent gases, or gases to be detected into the device. The gas entering from the peek material carrier gas inlet can be further sent into the thermal desorption cavity on the right side of the stainless steel metal heating block through the stainless steel gas inlet pipe.

The sample injection metal capillary tube extends into the metal heating block and is used for sending ions in the ionization cavity on the left side of the stainless steel metal heating block into a detection instrument at the rear end.

The working time sequence of the device is that a sample is loaded on the tetrafluoro sampling cloth firstly, when the sampling cloth is inserted into the device, the motor top head moves leftwards under the action of the transmission device to jack the tetrafluoro sampling cloth up to contact with the stainless steel metal heating block, the sample is instantaneously heated and analyzed into gas, and the high-temperature gas can be immediately diffused into the ionization cavity on the left side of the stainless steel metal heating block from the thermal desorption pool. Because the inside of the device is always kept at a constant high temperature, the sample is hardly remained to cause loss, the sample in the ionization cavity is ionized into ions under the irradiation of the radio frequency lamp and stays in the ionization cavity for a short time, and at the moment, a detection instrument at the rear end can extract the ions in the ionization cavity for analysis and detection. After the analysis and detection are finished, the peek material carrier gas inlet can be introduced into the clean gas cleaning device, so that the residue is further reduced.

Fig. 2 is a comparison of the results of two drugs detected by an in-situ thermal desorption photoionization device and a split detection device.

Papaverine has a boiling point of about 200 deg.C, and is a volatile drug. FIG. 2 (top spectrum) shows a mass spectrum with 0.1ng papaverine as the upper line and obtained using the in situ thermal desorption photoionization device of the present invention. 340 is the peak of the molecular ion plus proton of methamphetamine.

The boiling point of indole drugs is generally about 500 ℃, and the indole drugs belong to drugs which are difficult to volatilize. FIG. 2 (lower spectrum) is a mass spectrum of an indole drug with 0.1ng AM-2201 on the top line obtained by using the in situ thermal desorption photoionization device of the invention.