JP7364377B2 - Explosives inspection equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to an explosives testing device, and more particularly to cleaning of an explosives testing device.

Explosives inspection equipment is a device that detects and identifies substances that adhere to the surface of baggage, etc., and is used for security measures in places where a large number of unspecified people gather, such as airports and event venues. In explosives inspection equipment, substances adhering to a piece of paper that has been wiped off the surface of baggage, etc. are vaporized by heating the paper piece, further ionized, and then detected and identified using mass spectrometry. Although mass spectrometry is capable of detecting and identifying samples at the 10 ⁻¹⁵ g level, it is easily affected by residual substances, so it is important to remove residual substances by cleaning before analysis.

Patent Document 1 discloses that a desorption gas is selected based on the results of mass spectrometry in order to facilitate cleaning of substances adsorbed on the inner wall of a chemical substance monitoring device. Specifically, it is determined whether the adsorbed substance is a salt or an organic substance, and if it is a salt, water vapor is used as the desorption gas, and if it is an organic substance, cleaning is performed using an organic solvent gas as the desorption gas.

Japanese Patent Application Publication No. 2007-170985

However, in Patent Document 1, the desorption gas is simply selected depending on the type of adsorbed substance, and this may be inappropriate as a cleaning condition. If the cleaning conditions are inappropriate, the analytical accuracy of mass spectrometry may be reduced or cleaning may take a long time.

Therefore, an object of the present invention is to provide an explosives inspection device that can set more appropriate cleaning conditions.

In order to achieve the above object, the present invention is characterized in that heating temperature or gas flow rate is set as a cleaning condition based on the result of mass spectrometry obtained before cleaning, and cleaning is performed according to the set cleaning condition. .

More specifically, a sample heating section that vaporizes the sample to be inserted by heating to generate a vaporized sample, an ionization section that ionizes the vaporized sample to generate an ionized sample, and an ionization section that connects the sample heating section to the ionization section. An explosives testing device comprising: a flow rate adjustment section that adjusts a gas flow rate to the sample; a mass spectrometry section that performs mass spectrometry on the ionized sample; and a control section that controls each section; a mass spectrometry result acquisition unit that acquires the mass spectrometry results from the mass spectrometry unit before the mass spectrometry analysis, and a cleaning condition setting unit that sets the heating temperature of the sample heating unit or the gas flow rate as a cleaning condition based on the results. and cleaning is performed under the cleaning conditions described above.

According to the present invention, it is possible to provide an explosives inspection device that can set more appropriate cleaning conditions.

1 is a diagram showing an example of the configuration of an explosives inspection device according to a first embodiment; FIG. 3 is a diagram showing an example of the configuration of a sample heating section in Example 1. FIG. FIG. 3 is a diagram illustrating a configuration example of main parts of Example 1. FIG. FIG. 3 is a diagram illustrating an example of the flow of processing in the first embodiment. A diagram showing an example of a cleaning condition DB (Data Base). FIG. 3 is a diagram showing differences in changes in residual substances over time due to differences in cleaning conditions.

Preferred embodiments of the explosives testing device according to the present invention will be described below with reference to the accompanying drawings. Explosives inspection equipment is a device that detects and identifies substances that adhere to the surface of baggage, etc. It ionizes the vaporized substance by heating a piece of paper that has been wiped off the surface of baggage, etc., and then analyzes it using mass spectrometry.

An example of the overall configuration of the explosives testing device of this embodiment will be described with reference to FIG. The explosives testing device includes a sample heating section 1, a connection section 2, an ionization section 3, a mass spectrometry section 4, a flow rate adjustment section 5, a suction pump 6, and a control section 7. Each part will be explained below.

The sample heating unit 1 is a device that heats a piece of paper that has been wiped off the surface of baggage or the like, vaporizes a substance attached to the paper piece, and generates a vaporized sample. An example of the configuration of the sample heating section 1 will be explained using FIG. 2. The sample heating section 1 has a paper strip introduction port 21, an optical sensor 22, and a paper strip nipping section 23.

The paper strip inlet 21 is an opening into which a paper strip to which a substance to be analyzed is attached is inserted. The optical sensor 22 is a sensor that detects that a piece of paper has been inserted into the sample heating section 1. The paper piece nipping section 23 is a part that vertically sandwiches and heats the paper piece. The heating temperature of the paper piece sandwiching part 23 is set to a temperature at which the substance to be analyzed is vaporized, for example, 250°C. That is, when a piece of paper inserted from the paper piece introduction port 21 is detected by the optical sensor 22, the paper piece nipping section 23 pinches the piece of paper from above and below and heats it. Due to this operation, the substance attached to the paper piece is vaporized and a vaporized sample is generated.

Returning to the explanation of FIG. The connecting part 2 is a pipe that connects the sample heating part 1 and the ionizing part 3. The vaporized sample generated in the sample heating section 1 is supplied to the ionization section 3 via the connection section 2 . In order to prevent adsorption and recondensation of the vaporized sample, the connecting portion 2 is maintained at a predetermined temperature, for example 200°C.

The ionization unit 3 is a device that ionizes a vaporized sample to generate an ionized sample. APCI (Atmospheric Pressure Chemical Ionization) method, EI (Electron Ionization) method, etc. are used to ionize the vaporized sample. The ionized sample is supplied to the mass spectrometer 4.

The mass spectrometer 4 is a device that performs mass spectrometry on an ionized sample. Ionized samples are separated by mass/charge ratio, so-called m/z, and then detected individually. The separated and detected results for each m/z are transmitted to the control unit 7.

The suction pump 6 is a pump that sucks the inside of the ionization section 3 so that the vaporized sample generated in the sample heating section 1 is supplied to the ionization section 3 . The suction capacity of the suction pump 6 is, for example, 2.0 L/min.

The flow rate adjustment unit 5 is a valve installed between the ionization unit 3 and the suction pump 6, and is used to adjust the flow rate of gas sucked from the ionization unit 3. The gas flow rate is adjusted by the flow rate adjustment unit 5 to, for example, 0.6 L/min or 1.0 L/min.

The control unit 7 is a device that controls each part of the explosives testing device, and is configured by, for example, a computer. Further, the control unit 7 generates a mass spectrum in which the number of counts for each m/z is plotted, based on the detection results transmitted from the mass spectrometer 4. Since mass spectra differ depending on the substance, substances, especially explosives such as TNT (TriNitroToluene), can be identified from the obtained mass spectra. Note that a mass spectrum obtained by mass spectrometry of a known substance may be used to identify the substance. That is, a plurality of mass spectra of known substances may be recorded, and the substance may be identified by comparing the results of mass spectrometry of the substance to be analyzed with the recorded data group. The generated mass spectra and substance identification results are displayed on a display device such as a liquid crystal display.

Although it is possible to identify substances on the 10 ⁻¹⁵ g level by mass spectrometry, in order to maintain analysis accuracy, it is necessary to remove the substance to be analyzed and trace amounts of foreign matter by cleaning in advance. Furthermore, if the cleaning conditions are inappropriate, residual substances may reduce analysis accuracy or require a long time to remove residual substances. Therefore, in this embodiment, cleaning is performed by setting appropriate cleaning conditions based on the mass spectrometry results obtained from the mass spectrometry section 4 by starting each section before the sample is inserted into the sample heating section 1. do. Note that the cleaning conditions include the heating temperature of the sample heating section 1 and the gas flow rate adjusted by the flow rate adjustment section 5.

A configuration example of the main parts of this embodiment will be explained using FIG. 3. Note that these main parts may be configured with dedicated hardware or with software that operates on the control unit 7. In the following explanation, a case will be explained in which the main part of this embodiment is configured by software. This embodiment includes a mass spectrometry result acquisition section 31, a cleaning condition DB (Data Base) 32, and a cleaning condition setting section 33. Each part will be explained below.

Before the sample is inserted into the sample heating section 1, the mass spectrometry result acquisition section 31 transmits data to the sample heating section 1 and the ionization section 3 based on the mass spectrum generated by the detection results transmitted from the mass spectrometry section 4. Identify residual substances. The analysis for identifying residual substances in the sample heating section 1 and the ionization section 3 is also called background analysis. The results of the background analysis are sent to the cleaning condition setting section 33.

The cleaning condition setting unit 33 sets cleaning conditions based on the results of the background analysis. That is, the heating temperature of the sample heating section 1 and the gas flow rate adjusted by the flow rate adjustment section 5 are set as cleaning conditions suitable for removing residual substances identified as a result of the background analysis. When setting the heating temperature and gas flow rate, the cleaning condition setting unit 33 may check the results of the background analysis against the cleaning condition DB 32 that stores target components and cleaning conditions in association with each other.

An example of the processing flow of this embodiment will be explained using FIG. 4.

(S401)
The control unit 7 starts up each part of the explosion part inspection device, sets the sample heating part 1 to 250°C, the connection part 2 to 200°C, and adjusts the gas flow rate to 0.6L/ Adjust to min. Background analysis can be performed by bringing each part under normal measurement conditions before a sample is inserted into the sample heating part 1.

(S402)
When the control unit 7 causes the background analysis to be performed, the mass spectrometry result acquisition unit 31 acquires the results of the background analysis.

(S403)
The mass spectrometry result acquisition unit 31 determines whether the background analysis result exceeds a threshold value. The threshold value is acquired for each determination m/z value from the cleaning condition DB illustrated in FIG. 5, and is compared with the background analysis result. That is, if the background analysis result exceeds any threshold included in the cleaning condition DB, the process proceeds to S404, and if it does not, the process proceeds to S406.

For example, if the signal intensity of m/z=265 exceeds the threshold value 17000 in the mass spectrum generated based on the detection result in the mass spectrometer 4, from the cleaning condition DB in FIG. The substance remaining in the ionization section 3 is No. 1 explosive A is identified. Further, if the signal strength of m/z=62 exceeds the threshold value 20000, No. Explosive B of No. 2 is identified as residual material.

Note that even if the target component corresponding to the cleaning condition DB is not registered, if the signal strength exceeds a predetermined threshold value, for example 50,000, the residual substance may be determined to be an unknown component and the process may proceed to S404. . When a residual substance is identified as an unknown component, it is classified into either low boiling point or high boiling point, as shown in No. 4 and No. 5 in Figure 5, according to the m/z value that indicates the peak in the mass spectrum. Also good.

(S404)
The cleaning condition setting section 33 sets cleaning conditions. The cleaning conditions are set based on the identification result in S403. That is, the heating temperature of the sample heating section 1 and the gas flow rate adjusted by the flow rate adjustment section 5 are set as cleaning conditions suitable for removing residual substances in the sample heating section 1 and the ionization section 3. Specifically, the cleaning conditions are set by comparing the identification results in S403 with the cleaning condition DB illustrated in FIG. 5. For example, if explosive A is identified in S403, a heating temperature of 270° C. or a gas flow rate of 0.6 L/min is set.

The heating temperature is set to a temperature slightly higher than the boiling point Tb of the target component, for example, Tb+30. By setting the heating temperature to a temperature slightly higher than the boiling point Tb, the target component is sufficiently vaporized and removed by suction by the suction pump 6, and the time required for cooling after the temperature is raised can be shortened. In addition, when the boiling point is low like explosive B, since it is sufficiently vaporized even at the heating temperature of 250° C. under the normal measurement conditions, the same heating temperature as the normal measurement conditions may be set. However, in order to shorten the cleaning time, a gas flow rate larger than the normal measurement conditions may be set. Further, when the boiling point is high like explosive C, the same gas flow rate as the normal measurement conditions may be set in order to shorten the time required to raise the temperature.

(S405)
The control unit 7 cleans the explosive part inspection device according to the cleaning conditions set in S404. In particular, the sample heating section 1 and the ionization section 3, to which various substances tend to adhere when a sample is inserted, are cleaned. After the cleaning is performed, background analysis in S402 and threshold value determination in S403 are performed. That is, cleaning is repeated until the background analysis result becomes less than or equal to the threshold value.

(S406)
A piece of paper on which the surface of baggage or the like has been wiped is inserted into the sample heating section 1, and the control section 7 sets each section under normal measurement conditions, whereby substances contained in the paper piece are subjected to mass spectrometry. The mass spectrometry results are displayed on a display device. When a new sample is subjected to mass spectrometry, the analyzed sample is removed from the sample heating section 1, and then the process returns to S402.

According to the process flow described above, it is possible to perform mass spectrometry on a sample while the explosion part inspection device is sufficiently cleaned, so that high analysis accuracy can be achieved. Further, since the heating temperature of the sample heating section 1 and the gas flow rate adjusted by the flow rate adjustment section 5 are set based on the results of the background analysis, more appropriate cleaning conditions can be set. Since more appropriate cleaning conditions can be set, cleaning can be completed in a shorter time.

Differences in changes in residual substances over time due to differences in cleaning conditions will be explained using FIG. 6. As an example of residual substances, FIG. 6 shows the change over time of a highly volatile component, which is a fragrance-derived component having a peak at m/z=152, that is, a target component with a low boiling point. Since m/z=152 and less than 250, No. Cleaning conditions No. 4, namely, a heating temperature of 250° C. and a gas flow rate of 1.0 L/min, are set, and are shown by a solid line in FIG. As a comparison condition, the broken line shows the change over time when the normal measurement conditions were set to a heating temperature of 250° C. and a gas flow rate of 0.6 L/min.

In FIG. 6, it took 14 seconds for the signal strength of m/z=152 to fall below the threshold value of 50,000 on the broken line, whereas it took 8 seconds on the solid line. In other words, it was shown that by setting more appropriate cleaning conditions, cleaning can be completed in a shorter time.

The embodiments of the present invention have been described above. The present invention is not limited to the above-described embodiments, and the constituent elements may be modified without departing from the gist of the invention. Further, a plurality of components disclosed in the above embodiments may be combined as appropriate. Furthermore, some components may be deleted from all the components shown in the above embodiments.

1: Sample heating section, 2: Connection section, 3: Ionization section, 4: Mass spectrometry section, 5: Flow rate adjustment section, 6: Suction pump, 7: Control section, 21: Paper strip introduction port, 22: Optical sensor, 23 : Paper piece sandwiching part, 31: Mass spectrometry result acquisition part, 32: Cleaning condition DB, 33: Cleaning condition setting part

Claims (4)

a sample heating section that vaporizes the inserted sample by heating to generate a vaporized sample;
an ionization unit that ionizes the vaporized sample to generate an ionized sample;
a flow rate adjustment unit that adjusts the gas flow rate from the sample heating unit to the ionization unit;
a mass spectrometer that performs mass spectrometry on the ionized sample;
An explosives inspection device comprising a control unit that controls each part,
The control unit includes a mass spectrometry result acquisition unit that acquires a mass spectrometry result from the mass spectrometry unit before the sample is inserted, and a cleaning unit that cleans the heating temperature of the sample heating unit or the gas flow rate based on the result. a cleaning condition setting section for setting conditions, and cleaning according to the cleaning conditions ;
When the heating temperature is lower than the temperature at which the sample heating section heats the sample, the cleaning condition setting section increases the gas flow rate when mass spectrometry is performed on the ionized sample. Inspection equipment. The explosives inspection device according to claim 1,
The explosives testing device is characterized in that the cleaning condition setting unit sets the cleaning conditions by collating the results in a cleaning condition DB that stores target components and cleaning conditions in association with each other. The explosives inspection device according to claim 1,
An explosives testing device characterized in that the heating temperature is higher than the boiling point of the target component. The explosives inspection device according to claim 1,
An explosives testing device characterized in that cleaning is repeated until the signal strength of the target component included in the result becomes equal to or less than a threshold value.

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