JP4877335B2 - Chemical substance detection apparatus and chemical substance detection method - Google Patents

Description

  The present invention relates to a chemical substance detection technique for environmental substances, harmful chemical substances, narcotics, explosives, and the like, and more particularly to a chemical substance detection apparatus using a mass spectrometer.

  The detection technology for detecting narcotics and explosives includes so-called bulk detection that distinguishes from the shape and density of an object like an X-ray fluoroscopy device, and so-called trace detection that detects a very small amount of chemical substances adhering to the inspection target. It is divided roughly into. Techniques for detecting explosives in trace detection include chemiluminescence, ion mobility, and mass spectrometry.

  In the chemiluminescence method, a collected sample is separated by gas chromatography and reacted with a luminescent reagent to detect luminescence, thereby identifying a chemical substance and detecting an explosive (refer to Patent Document 1: Patent Document 1). . Since the collected substance is separated in advance by a gas chromatograph, it is extremely sensitive to a specific detection target substance and has a high ability to distinguish the substance (hereinafter referred to as selectivity).

  In the ion mobility method, a collected sample is heated and vaporized, and a gaseous sample is ionized with an ion source using radiation. The ions are drifted in the atmosphere by an electric field, and the chemical substance is identified by measuring the mobility, and explosives are detected (refer to Prior Art 2: Patent Document 2).

  In the ion mobility method, the introduction of chlorine or a chlorine compound (hereinafter referred to as chlorine dopant) during ionization causes the explosive molecules to react with the chlorine ions, and the addition of chlorine ions to the explosive molecules. Generate ions. Explosives are detected by detecting these additional ions. (Refer to Prior Art 3: Patent Document 3). In the method of detecting the adduct ion of chlorine ion, since the generation efficiency of the adduct ion is high, the observed signal intensity is high, and the sensitivity at the time of detection is high. In addition, ions obtained by ionizing the detection target substance through the original ionization process are also observed at the same time as the additional ions by chlorine, so that the number of signals increases and the selectivity increases.

  As a detection apparatus using a mass spectrometry method, a method using an atmospheric pressure chemical ionization method is known (refer to Prior Art 4: Patent Document 4). In this method, explosive molecules are ionized by chemical reaction under atmospheric pressure, and mass identification of the generated ions is performed to identify substances and detect explosives. Since the collected material is directly introduced into the atmospheric pressure ion source and mass spectrometry is performed, pretreatment such as concentration and separation is not required, and continuous and speedy detection is possible. Further, the negative atmospheric pressure chemical ionization method has a feature of selectively ionizing a nitro compound having a high electron affinity, and is not easily affected by impurities, and has high sensitivity because of high signal intensity. In addition, since the detection unit uses a mass spectrometer used for fine chemical analysis such as a quadrupole mass spectrometer or an ion trap mass spectrometer, the difference in molecular weight 1 can be discriminated, so that the selectivity is high. For this reason, even in actual operation, it is possible to distinguish between the contaminating component and the substance to be detected.

  Also in the mass spectrometry method, a method for detecting an adduct ion in which a chlorine ion is added to an explosive molecule using a chlorine dopant has been proposed (see Prior Art 5: Non-Patent Document 1).

  In mass spectrometry of organic polar compounds, an organic polar compound containing a hydroxyl group or a carboxyl group is mixed with a halogen compound and used for ionization of the halogen compound (see Prior Art 6: Patent Document 5).

  A method of performing tandem mass spectrometry simultaneously when there are a plurality of molecular species to be measured in monitoring a chemical substance using a mass spectrometry method is disclosed. (See Prior Art 7: Patent Document 6).

US Pat. No. 5,092,155 Japanese Patent Laid-Open No. 5-264505 JP 7-6729 A JP 2000-28579 A Japanese Patent No. 2667576 JP 2000-162189 A

7th International Symposium on Analysis and Detection of Explosives, 2001, Samantha L. Richards et al, The Detection of Explosive Residues from Boarding Passes, PP.60

  In the method of the prior art 1, since a pretreatment for concentrating the collected material or separating the collected material by a gas chromatograph is necessary, it takes time until detection. For this reason, it is not suitable for a large number of inspections such as baggage inspections at airports.

  In the method of Prior Art 2, detection in a short time is possible, but it is difficult to obtain a sufficient signal intensity for the detection target substance, and the sensitivity is low. Moreover, since it is made to drift under atmospheric pressure conditions with many collisions, the separation is poor and the selectivity is low. If the selectivity is low, there is a problem that there are inevitably many false alarms.

  In prior art 3, a low concentration chlorine dopant is introduced in order to solve the problems of sensitivity and selectivity of prior art 2. However, although it can be said that the sensitivity is high in detection in a clean environment, there are many interfering substances other than those to be detected in actual operation, and sufficient sensitivity and selectivity are expected in operation in the environment of the interfering substance. It cannot be said that has been obtained. This interfering component is referred to as a “contaminating component” in the following. For example, considering a bag wiping test, the component derived from the bag (such as the smell of the material of the bag itself), dirt, oil, and cosmetics attached to the surface of the bag To do. In other words, there are many false detections in which a miscellaneous component other than the detection target substance is erroneously determined or a plurality of similar detection target substances are erroneously determined. In addition, since a chlorine compound is used as a dopant raw material, there is a possibility of affecting the human body and the environment. Furthermore, since radioisotopes are used in the ion source, permission is required for use and storage, which is an operational limitation.

  In Prior Art 4, the collected material is directly introduced into the ion source at atmospheric pressure and mass spectrometry is performed. However, further improvement in sensitivity and selectivity has been desired.

  In prior art 5, in order to obtain further sensitivity improvement and selectivity improvement in the mass spectrometry method, as in the prior art 3, a chlorine dopant is introduced to detect a chlorine adduct ion in which a chlorine ion is added to a detection target substance. Have a way to go. However, since chlorine compounds are used, it may affect the human body and the environment.

The prior art 6 is an effective method for detecting halides, but has little effect on nitro compounds containing many explosives.
In the prior art 7, tandem mass spectrometry is effectively used for eliminating contaminant components, but further measures are required for detection of trace components such as explosive detection.

  An object of the present invention is to provide a dangerous object detection device excellent in speed, sensitivity, and selectivity. Another object of the present invention is to provide a high-performance detector that does not use substances such as radioisotopes and halides that are likely to affect the human body and the environment.

  The present invention is based on the newly discovered that in a negative atmospheric pressure chemical ionization method, ions in which a substance having a relatively large molecular weight such as an organic acid is added to an explosive molecule represented by a nitro compound are generated. It was done.

  In the chemical substance detection apparatus of the present invention, an organic acid or an organic acid salt (hereinafter, these are all referred to as an organic acid, and an organic acid gas is referred to as an organic acid dopant) is generated from a generator that generates an organic acid gas. Then, it is mixed with a sample gas and introduced into an ion source to perform ionization. This ion is analyzed by a mass spectrometer to obtain a mass spectrum. The data processor compares the mass spectrum with the database of detection. Data processing device detects molecules generated from organic acids into molecules generated from target chemical substances to be detected (organic acids, molecules generated by decomposition of organic acids, organic acids react with other molecules) The presence or absence of detection of an adduct ion (hereinafter referred to as an organic acid adduct ion) added with a generic name of the molecule thus formed, hereinafter referred to as an organic acid molecule) is determined. When an organic acid addition ion having this specific m / z is detected, it is judged that the target chemical substance to be detected exists and an alarm is sounded.

  The chemical substance detection apparatus of the present invention will be described in more detail below.

  The chemical substance detection apparatus of the present invention includes an ion source, an analysis unit, and a data processing device (data processing unit). The sample is ionized by the ion source, and the ion species of the sample is measured by the analysis unit. The data processing apparatus determines whether or not the target chemical substance to be inspected exists in the sample. The data processing apparatus determines the presence or absence of detection of product ions generated by the reaction between the target chemical substance molecule and the organic acid or organic acid salt molecule having a mass number of 40 or more and 400 or less. As a result of this determination, if it is determined that there is, an alarm is sounded.

  The analysis unit analyzes ion species, and is selected from a quadrupole mass spectrometer, an ion trap mass spectrometer, and an ion mobility analyzer. For example, a mass analyzer that acquires a mass spectrum of ions of a sample is used as the analyzer.

  The organic acid or organic acid salt is an organic acid or organic acid salt having a hydroxyl group or a carboxyl group, and typically lactic acid or lactate is used.

  The data processing device (1) determines the presence or absence of detection of the generated ions, or the presence or absence of detection of the generated ions generated by the reaction between the molecule generated from the organic acid or the organic acid salt and the molecule of the target chemical substance, (2) Presence / absence of detection of ions generated from the target chemical substance, presence / absence of detection of the above-mentioned generated ions, and detection of ions generated by reaction of molecules generated from organic acids or organic acid salts with molecules of the target chemical substance The presence / absence of any one or more detections is determined, and the presence / absence of the target chemical substance is determined.

  The chemical substance detection apparatus of the present invention performs tandem mass spectrometry.

  (1) Tandem mass spectrometry is performed on the product ions. The data processing apparatus determines whether or not the decomposition ions of the generated ions are detected, and determines whether or not the target chemical substance is present.

  (2) Tandem mass spectrometry is performed on ions generated by the reaction between molecules generated from organic acids or organic acid salts and molecules of the target chemical substance. The data processing device determines whether or not the decomposition ions of the generated ions are detected, and determines whether or not the target chemical substance is present.

  (3) For any one or more of the ions generated from the target chemical substance, the above-mentioned generated ions, and the ions generated by the reaction of the molecule generated from the organic acid or organic acid salt with the molecule of the target chemical substance Simultaneously perform tandem mass spectrometry. The data processing apparatus determines whether or not the decomposition ions of the ions generated from the target chemical substance are detected and whether or not the decomposition ions of the generated ions are detected, and determines whether or not the target chemical substance exists.

  In the configuration example of the chemical substance detection apparatus of the present invention, the heating unit that generates a sample gas, the gas generator that generates an organic acid or organic acid salt gas having a mass number of 40 to 400, and the heating unit The sample gas is mixed with an organic acid or organic acid salt gas to generate a mixed gas, a mass analyzer for obtaining a mass spectrum of ions of the mixed gas, and an inspection based on the mass spectrum. And a data processing device for determining the presence or absence of the target chemical substance in the sample.

  In another configuration example of the chemical substance detection apparatus of the present invention, a suction unit that sucks a sample gas, a gas generator that generates an organic acid or organic acid salt gas having a mass number of 40 or more and 400 or less, and a suction unit Based on the mass spectrum, a gas mixing unit that generates a mixed gas by mixing a gas of an organic acid or an organic acid salt with the aspirated sample gas, a mass analysis unit that acquires a mass spectrum of ions of the mixed gas, And a data processing device for determining the presence or absence of the target target chemical substance in the sample gas.

  In another configuration example of the chemical substance detection apparatus of the present invention, a wipe member that is impregnated with an organic acid or an organic acid salt having a mass number of 40 or more and 400 or less, collects a sample from an inspection object, and heats the wipe member to sample A heating unit that generates a mixed gas in which a gas of an organic acid or an organic acid salt is mixed, a mass analyzer that acquires a mass spectrum of ions of the mixed gas, and an object to be inspected based on the mass spectrum And a data processing device for determining the presence or absence of the chemical substance in the sample.

  In the above configuration example, the data processing device determines the presence or absence of detection of product ions generated by the reaction between the molecule of the target chemical substance and the molecule of the organic acid or organic acid salt, and the presence or absence of the target chemical substance. Determine.

  In the chemical substance detection method of the present invention, based on the result of ionization of the sample, the step of analyzing the ion species of the sample, and the analysis result of the ion species, the molecule of the target chemical substance and the mass number of 40 or more and 400 or less And a step of determining the presence or absence of detection of a product ion generated by the reaction with an organic acid or organic acid salt molecule, and determining the presence or absence of the target chemical substance.

  In the chemical substance detection method of the present invention, a step of generating a sample gas, a step of mixing a gas of an organic acid or an organic acid salt having a mass number of 40 or more and 400 or less into the sample gas, and generating a mixed gas, Determining whether or not to detect the ions produced by the reaction between the ionization of the mixed gas, the mass spectrum of the ions in the mixed gas, and the molecules of the target chemical substance and the organic acid or organic acid salt molecule And a step of determining the presence or absence of the target chemical substance.

  According to the present invention, by adding an organic acid, the detection sensitivity can be increased with less consumption than conventional chlorine dopants. In addition, organic acids tend to be negative ions and easily generate additional ions with explosive molecules, making them suitable for explosives detection devices. Further, since the organic acid addition ion is detected at a mass number higher than that of the chlorine addition ion, it can be easily distinguished from the molecular ion generated from the detection target substance, and the selectivity is improved. As a result, erroneous detection can be prevented.

The figure which shows the structural example of the explosives detection apparatus of Example 1 of this invention. It is a figure which shows an example of the ion source and analysis part in Example 1 of this invention. The figure which shows an example of the mass spectrum of a chlorine addition ion obtained with the conventional explosives detection apparatus. The figure which shows an example of the mass spectrum of the organic acid addition ion obtained by the explosives detection apparatus of the Example of this invention. The figure which shows the mass spectrum of only the explosive RDX obtained in the explosives detection apparatus by the conventional mass spectrometer. The figure which shows the mass spectrum of explosive RDX obtained when lactic acid is used as an organic acid dopant in Example 1 of this invention. The figure which shows an example of the explosive detection flowchart in the explosive detection apparatus of Example 1 of this invention. The figure which shows the change of the signal intensity | strength of the chlorine addition ion with respect to a chlorine concentration at the time of using a chlorine dopant in the explosive substance detection apparatus of Example 1 of this invention. The figure which shows the change of the signal strength of the lactic acid addition ion with respect to a lactic acid density | concentration at the time of using a lactic acid dopant in the explosives detection apparatus of Example 1 of this invention. In Example 2 of this invention, the figure which shows the fragment mass spectrum by tandem mass spectrometry of RDX lactic acid addition ion. The figure which shows the structural example of the explosives detection apparatus of Example 4 of this invention. The figure which shows the structural example of the explosives detection apparatus of Example 5 of this invention. In Example 6 of this invention, the figure which shows the mass spectrum of explosive RDX obtained when succinic acid is used as a dopant. The figure which shows the mass spectrum of explosive RDX obtained when butyric acid is used as a dopant in Example 6 of this invention. The figure which shows the mass spectrum of explosive RDX obtained when using sodium lactate as a dopant in Example 6 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  3, 4, 5, 6, 10, 13, 14, and 15 described below, the horizontal axis represents m / z, and the vertical axis represents signal intensity.

  The chemical substance detection apparatus of the present invention can detect environmental substances, harmful chemical substances, narcotics, and explosives by detecting ions generated by reaction with molecules generated from organic acids or organic acid salts. Is possible.

  In the following description, an explosive detection device will be described as an example of a chemical substance detection device. Although RDX was used as an example of an explosive, it is not limited to this.

  First, as a comparison with the present invention, a mass spectrum obtained by a conventional method using a chlorine dopant will be described for reference.

A mass spectrum when a chlorine dopant is introduced will be described with reference to FIG. Usually, when no chlorine dopant is introduced, the ion peak of the molecular ion ((M) ⁻ ) of the detection target substance, and the specific specific molecule desorption ion ((M ₁ ) ⁻ ) or specific molecule generated from the detection target substance Additional ions ((M ₂ ) ⁻ ) are detected. By introducing a chlorine dopant, an ion peak of chlorine ions ((Cl) ⁻ ) is detected. Further, a chlorine addition ion ((M + Cl) ⁻ ) in which a chlorine ion is added to the detection target substance is detected. When an appropriate amount of chlorine dopant is introduced, a chlorine adduct ion is efficiently generated. Therefore, a specific ion peak generated from a substance to be detected when chlorine is not introduced, that is, (M) ⁻ , (M ₁ ) ⁻ and (M ₂₎ ^- stronger than the intensity of chlorine adduct ion than the signal strength of the. In other words, even if the amount of the detection target substance is small, the signal of the ion peak of the chlorine addition ion is strongly observed, so that the sensitivity becomes high and even a very small amount of sample can be detected. Moreover, since the ion peak of the chlorine addition ion is detected at a position having a mass number higher than that of chlorine (mass numbers 35 and 37) together with the ion peak of the detection target substance, detection and determination are performed with a plurality of ion peaks. And the selectivity is improved.
FIG. 4 is a diagram showing an example of a mass spectrum of an organic acid addition ion obtained by the explosive detection device of the embodiment of the present invention.
A mass spectrum obtained when the organic acid dopant of the present invention is used will be described with reference to FIG. Usually, when an organic acid dopant is not introduced, an ion peak of a molecular ion ((M) ⁻ ) generated from the detection target substance, a specific molecular desorption ion ((M ₁ ) where a specific molecule is desorbed from the detection target substance) ^- ), Or the added specific molecule addition ion ((M ₂ ) ^- ) is detected. By introducing the organic acid dopant, ions ((D) ⁻ ) generated from the organic acid molecule are detected. Further, an organic acid addition ion ((M + D) ⁻ ) added with an organic acid molecular ion is detected.
Depending on the organic acid and the type of explosive to be detected, hydrogen desorbed (M + D−H) ⁻ or hydrogen added (M + D + H) ⁻ may be detected. In addition, since a plurality of types of ions generated from the organic acid may be obtained, a plurality of types of organic acid addition ions may be obtained. There are various types of explosives to be detected, and the addition reaction between explosives and ions generated from organic acids is complicated, so it is difficult to predict in advance what kind of additional ions will be obtained. Therefore, it is important to acquire a detection database based on experiments, and the presence or absence of the target substance is determined based on the detection database stored in the data processing apparatus.

  FIG. 1 is a diagram illustrating a configuration example of an explosive detection device according to a first embodiment of the present invention. The chemical substance detection apparatus according to the first embodiment has a wipe-type apparatus configuration using an organic acid gas generator.

  As shown in FIG. 1, the apparatus comprises a suction unit 1 (upper heater) and a heater 2 having a lower heater, an organic acid gas generator 3, an ion source 4, a mass analyzer 5, and a data processor 6. Composed. The organic acid gas generator 3 is charged with about 400 μL (microliter) of lactic acid, which is an example of an organic acid, and heated to about 40 ° C. by the generator heater 9 to generate lactic acid vapor. Further, it is introduced into the ion source 4 at a flow rate of about 0.1 L (liter) / min by the extrusion pump 7 and the extrusion mass flow controller 8. In that case, the extrusion flow rate should just be a flow rate which does not flow backward to the suction part 1 side.

  Gas is drawn into the ion source 4 at a flow rate of about 0.5 L / min by the intake pump 10 and the intake mass flow controller 11 in order to suck vapor or fine particles from the suction unit 1. In the ion source 4, the sample is ionized. Ions generated by the ion source 4 are taken into the mass analyzer 5 evacuated to a vacuum through pores having an inner diameter of about 0.2 mm. Since the gas is drawn from the pores to the mass analysis unit 5 side at about 0.5 L / min, the flow rate of the sample gas sucked from the suction unit 1 is about 0.9 L / min.

  In the inspection, baggage and the like are wiped off with a wipe 12, and a very small amount of explosive component is collected. This wipe material 12 is inserted into a heater 2 composed of a suction unit 1 (upper heater) and a lower heater. The suction part 1 (upper heater) and the heater 2 only need to be held at a temperature at which the collected sample evaporates. This time, both were heated at 210 ° C.

When the wipe material 12 is inserted, the heater 2 rises, and the wipe material 12 is sandwiched and heated to evaporate the explosive sample. The evaporated sample passes through a heated filter 13 (for example, heated at 210 ° C.) and a pipe 14 (for example, heated at 180 ° C.) heated by a pipe heater 15, and then an organic acid. The lactic acid vapor generated in the gas generator 3 is mixed in the mixing unit 16 and introduced into the ion source 4. The filter 13 is provided to prevent dust and the like from being sucked. The ion source 4 ionizes the mixed gas, and the mass analyzer 5 performs mass analysis.
Next, details of the ion source and mass spectrometry will be described.
FIG. 2 is a diagram illustrating an example of an ion source and an analysis unit in the chemical substance detection apparatus according to the first embodiment of the present invention.

Any ion source may be used as long as it can generate the ion species of the sample. For example, a radiation source, electron beam, light, laser, corona discharge, or the like can be used. The analysis unit is not limited as long as it can analyze the ion species, and may be an ion mobility method, for example.
FIG. 2 shows a configuration in which an atmospheric pressure ionization method is used for the ion source and an ion trap mass spectrometer is used for analyzing the ion species. In this ion source, primary ions are generated using corona discharge in the atmosphere, and sample molecules are ionized using a chemical reaction between the primary ions and sample molecules. The needle electrode 17 is disposed in the ion source, a high voltage is applied between the counter electrode 18 and a corona discharge is generated near the tip of the needle electrode. By this corona discharge, nitrogen, oxygen, water vapor, etc. in the air are ionized to become primary ions.

  The generated primary ions move to the pored electrode (first pore) 19 side by an electric field. The vapor or fine particles of the sample containing the substance to be detected sucked through the pipe flows into the needle electrode 17 side through the opening of the counter electrode 18. In that case, vapor | steam or microparticles | fine-particles are ionized by reacting with a primary ion. In the negative ionization mode in which a negative high voltage is applied to the needle electrode 17 to generate negative ions, the primary ions are often oxygen molecular ions. A typical negative ionization reaction in the sample molecule (M) is shown below.

M + (O2) − → M− + O2
Since the generated sample molecular ions have a potential difference of about 1 kV between the counter electrode 18 and the electrode with pores (first pore) 19, they move to the electrode side with pores (first pore) 19, The differential exhaust part 21 is entered through the one pore 20. In the differential exhaust part 21, adiabatic expansion occurs, and clustering in which solvent molecules adhere to ions occurs. In order to reduce this clustering, it is desirable to heat the electrode with pores (first pore) 19 with a heater or the like.

  When the ion source having the structure shown in FIG. 2 is used, primary ions generated by corona discharge move from the counter electrode 18 toward the electrode with pores (first pore) 19. On the other hand, vapor or particulate gas containing sample molecules is supplied between the counter electrode 18 and the electrode with pores (first pore) 19 to cause an ionization reaction with primary ions. At this time, neutral molecules that inhibit the ionization reaction such as neutral nitric oxide (NO) generated by corona discharge flow in the direction from the counter electrode 18 to the needle electrode 17, so that the primary molecules and the primary molecules are primary. Ions are removed from the region where the ionization reaction occurs. Since the primary ion generation region by corona discharge and the ionization reaction region between the primary ions and the sample molecules are thus separated, nitric oxide (NO) generated by the discharge and nitric oxide (NO) derived from the sample Can now be identified.

  The generated sample molecular ions are the first pore 20 opened in the electrode with pores (first pore) 19, the differential exhaust part 21 exhausted by the first exhaust system 24, the electrode with pores (first electrode). It is introduced into the vacuum part 26 evacuated by the second exhaust system 25 through the second pore 23 opened in the second pore 22.

  A voltage called a drift voltage is applied between the electrode with pores (first pore) 19 and the electrode with pores (second pore) 22. The drift voltage has the effect of improving the ion transmittance of the second pore 23 by drifting the ions taken into the differential exhaust portion 21 in the direction of the second pore 23, and the differential exhaust portion 21. There is an effect of desorbing solvent molecules such as water adhering to ions by collision with the remaining gas molecules.

  Further, an acceleration voltage is applied to the electrode with pores (second pore) 22 to introduce sample molecular ions into an ion trap part composed of the end cap electrodes 27 and 28 and the ring electrode 29. At this time, since the incident energy to the ion trap changes depending on the acceleration voltage, the ion confinement efficiency in the ion trap changes. Therefore, the acceleration voltage is set so as to increase the confinement efficiency.

  The ions introduced into the vacuum unit 26 are converged by the ion focusing lens 30 and then introduced into the ion trap unit. The ion trap part is composed of end cap electrodes 27, 28, a ring electrode 29, and a quartz ring 31, and a collision gas such as helium is introduced from a gas supply device 32 through a gas introduction pipe 33. The quartz ring 31 maintains electrical insulation between the end cap electrodes 27 and 28 and the ring electrode 29. The gate electrode 34 serves to control that ions are not newly introduced into the ion trap from the outside at the timing of analyzing the ions trapped in the ion trap portion.

  The ions introduced into the ion trap have a smaller orbit due to collision with a collision gas such as helium, and then scanned with a high-frequency voltage applied between the end cap electrodes 27 and 28 and the ring electrode 29, whereby the mass number Every time, ions are discharged out of the ion trap. The discharged ions are detected by a detection unit including the conversion electrode 34, the scintillator 35, and the photomultiplier 36. The ions collide with the conversion electrode 34 to which an accelerating voltage is applied, and charged particles are released from the surface. The charged particles are detected by the scintillator 35 and amplified by the photomultiplier 36. The detected signal is sent to the data processing unit 37. Details of the mass spectrum obtained by the data processing unit 37 will be described below.

  FIG. 5 is a diagram showing a mass spectrum of explosive RDX obtained using a conventional explosive detection device using a mass spectrometer. RDX is an explosive often used as a main component of plastic explosives.

As shown in FIG. 5, at m / z = 46, 267, an intrinsic m / z molecular ion (RDX-derived ion) generated from the explosive RDX is detected as an ion peak. It is estimated that m / z = 267 is (M + NO ₂ ) ⁻ and 46 is (NO ₂ ) ⁻ . In the conventional explosive detection device, detection is carried out using the ion peak of a specific molecular ion of m / z generated from this explosive as a detection target.

  FIG. 6 is a diagram showing a mass spectrum of explosive RDX obtained when lactic acid is used as the organic acid dopant in Example 1 of the present invention.

As shown in FIG. 6, a molecular ion (lactic acid-derived ion) generated from lactic acid as a dopant is detected as an ion peak at m / z = 89. It is estimated that m / z = 89 is an ion from which hydrogen is eliminated from lactic acid. Similar to FIG. 5, an intrinsic m / z molecular ion (ion derived from RDX) generated from the explosive RDX is detected as an ion peak at m / z = 46,267.
In addition to the intrinsic m / z ion peak generated from the explosive RDX, the ion peak of a molecular ion (RDX lactic acid-derived adduct ion) in which a molecule generated from lactic acid is added to the explosive RDX at m / z = 310. Is detected. In this case, lactic acid molecules (mass number 89) are added to explosive RDX (mass number 222), and hydrogen (mass number 1) is desorbed. Therefore, RDX can be detected by detecting a specific m / z ion peak (310 in the case of RDX) in which a molecule generated from lactic acid is added to the explosive molecule.

  FIG. 7 is a diagram illustrating an example of an explosive detection flowchart in the explosive detection apparatus according to the first embodiment of the present invention.

  As shown in FIG. 7, the inspection is started, the mass spectrum is measured, and sent to the data processing unit of FIG. From the mass spectrum sent to the data processing unit in FIG. 1, it is determined whether or not there is an inherent m / z ion peak generated from the detection target substance to be detected, and an alarm is sounded if detected. . Furthermore, even if a specific m / z ion peak generated from the substance to be detected is not detected, it is detected by determining the presence or absence of a specific m / z ion peak added by a molecule generated from lactic acid. If an alarm occurs, an alarm will sound.

  That is, when either an m / z ion peak of a molecule generated from a detection target substance or a specific m / z ion peak obtained by adding a molecule generated from lactic acid to the detection target substance is detected, An alarm may be sounded. By repeating these operations, it functions as an explosive detection device.

  In addition, as in the case where both an intrinsic m / z ion peak generated from the detection target substance and an intrinsic m / z ion peak to which molecules generated from the detection target lactic acid are added are detected, When the determination is made based on the presence or absence of a plurality of ion peaks, there is an effect that the certainty is higher than the determination by a single ion peak, and the false alarm can be reduced. As described above, since the organic acid dopant is used, two or more types of ions, that is, a signal derived from the original explosive and an additional ion obtained by adding an ion generated from the organic acid to the explosive molecule, are selected for detection. Improves.

  Data processing is performed in advance on the specific m / z ion peak generated from the detection target substance used for detection or the specific m / z ion peak added by the molecule generated from lactic acid to the detection target substance. The explosives other than this RDX are registered in the database in the department or outside, and the specific m / z ion peak generated from the detection target substance or the molecule generated from lactic acid in the detection target substance The added information on the specific m / z ion peak is registered in the database to increase the number of substances to be detected.

  FIG. 8 is a diagram showing a change in the signal intensity (vertical axis) of the chlorine-added ion with respect to the chlorine concentration (horizontal axis) when a chlorine dopant is used in the explosive substance detection apparatus of Example 1 of the present invention.

  FIG. 9 is a diagram showing a change in the signal intensity (vertical axis) of lactic acid addition ions with respect to the lactic acid concentration (horizontal axis) when a lactic acid dopant is used in the explosive detection device of Example 1 of the present invention. Lactic acid dopant means lactic acid introduced into the apparatus.

  As shown in FIG. 8, when a chlorine dopant is introduced into the apparatus, a chlorine concentration of 100 ppm is required to obtain a signal intensity of chlorine addition ions (RDX + Cl) of 1.0E + 7Counts or more.

  As shown in FIG. 9, in the case of a lactic acid dopant, a signal intensity of lactic acid adduct ion (RDX + La) is 1.0E + 7Counts or more at a lactic acid concentration of 10 ppm. Accordingly, the lactic acid dopant is more effective than the chlorine dopant. Accordingly, the lactic acid dopant consumes less and requires less work such as replenishment of the dopant agent. In addition, the lactic acid dopant is less likely to affect the environment and the human body than the chlorine dopant.

In addition, the molecular number (mass number 89) generated from lactic acid is larger than the mass number of chlorine ions (mass numbers 35 and 37), and is a specific molecule that is easy to add to explosives (NO ₂ ) ^- (mass number 46) and (NO ₃₎ - ^(for mass number than the mass number 62) is large, when added to the explosive, the additional ion peak was detected at a higher mass number than other additional easily identify molecules The This is because the separation of the ion peak added by a specific molecule and the lactate-added ion peak is easier than the chlorine-added ion peak, so even if a detection method with low selectivity such as the ion mobility method is used. There is an advantage that detection is reduced.

  In the second embodiment, an explosive detection device that detects tandem mass spectrometry of explosive lactic acid adduct ions and detects dissociated specific fragment ions will be described.

  Tandem mass spectrometry is known as a method for enhancing selectivity in a mass spectrometer. As a device for performing this tandem mass spectrometry, there are a triple quadrupole mass spectrometer, a quadrupole ion trap mass spectrometer, and the like. In tandem analysis, mass spectrometry is performed in two stages. As the first-stage mass analysis, m / z of ions generated by the ion source is measured. An ion having a specific m / z is selected from ions having various m / z.

  The selected ions (precursor ions) are dissociated by collision with a neutral gas or the like to generate decomposition product ions (fragment ions). Mass analysis of fragment ions is performed as the second stage mass analysis. When the precursor ion is dissociated, which part of the molecule is cut depends on the strength of the chemical bond for each part. Therefore, when the fragment ion is analyzed, a mass spectrum including information on the molecular structure of the precursor ion can be obtained.

  That is, even if the m / z of the ions generated by the ion source is coincidentally the same, it can be determined whether or not an object to be detected is included by examining the mass spectrum of the fragment ions. Tandem mass spectrometry using a triple quadrupole mass spectrometer or a quadrupole ion trap mass spectrometer is widely known and will not be described in detail.

  Details of tandem mass spectrometry performed on RDX, which is a type of typical explosive, will be described. An RDX lactic acid addition ion of m / z = 310 is selected as a precursor ion to exclude other ions. Furthermore, energy is applied to the precursor ions to dissociate them, and a mass spectrum of fragment ions is obtained.

  FIG. 10 is a diagram showing a fragment mass spectrum of RDX lactic acid adduct ion by tandem mass spectrometry in Example 2 of the present invention. FIG. 10 is a diagram showing an example of a fragment mass spectrum obtained by performing tandem mass spectrometry on the precursor ion of the explosive RDX lactic acid addition ion (m / z = 310) when a lactic acid dopant is introduced into the apparatus.

  Specific fragment ions generated by dissociation and decomposition from the explosive RDX are detected as ion peaks at m / z = 46 and 92. These are fragment ions generated by decomposing from RDX (fragment ions derived from RDX).

Furthermore, an ion peak is detected at m / z = 89,135 as fragment ions. These are fragment ions generated from lactic acid (fragment ions derived from lactic acid). By operating the fragment ion shown in FIG. 10 as a detection target and monitoring it, it operates as an explosive detection device.
Also, tandem mass spectrometry can be performed on ions generated only from explosives such as m / z = 267, combined with the results of tandem mass spectrometry of lactate-added ions, and judgment can be further improved. good.
Also, depending on the explosives, when lactic acid addition ions are subjected to tandem mass spectrometry, both intrinsic fragment ions generated from lactic acid and fragment ions generated from explosives may be obtained strongly. It is preferable to use the generated fragment ions as the detection target because the molecular structure of the explosive is well expressed. Alternatively, both a fragment ion of a molecule generated from lactic acid and a fragment ion of a molecule generated from an explosive may be detected.

  In Example 3, an ion generated from an explosive and an ion obtained by adding a molecule generated from lactic acid to the explosive are simultaneously dissociated and decomposed by tandem mass spectrometry to obtain a fragment ion of the explosive or a molecule generated from lactic acid. The explosive detection device to be detected will be described.

  In the case of normal tandem mass spectrometry, analysis is performed on one precursor ion. In Example 3, tandem mass spectrometry was performed on two or more precursor ions at the same time. Ions generated from the explosive are detected as a plurality of ion peaks. Similarly, a plurality of ion peaks in which molecules generated from lactic acid are added to the explosive may be detected. Some of these many ion peaks are selected as precursor ions and dissociated. This method may generate the same fragment ion with an ion generated from an explosive and a lactate-added ion, and is particularly effective in such a case. When fragment ions dissociated from a plurality of ion peaks have the same m / z, when tandem mass spectrometry is performed on all of the plurality of ion peaks at the same time, the m / z of the detected fragment ions is the same, so integration is performed. Detected as an ion peak. That is, the signal intensity is higher than when tandem mass spectrometry is performed alone, and the detection sensitivity is improved.

  The case of RDX will be described. In the case of RDX, m / z = 267 is an ion generated from the explosive. When this is subjected to tandem mass spectrometry, fragment ions are detected at m / z = 46 and 92. In addition, when tandem mass spectrometry is performed on m / z = 310 as a lactic acid addition ion, fragment ions generated from explosives at m / z = 46 and 92, and lactic acid at m / z = 89 and 135, The generated fragment ions are detected. If tandem mass spectrometry is performed simultaneously with m / z = 267 and m / z = 310, the fragment ions of m / z = 46 and 92 generated from the explosives are ions that are accumulated when performed independently. Detected as a peak signal. That is, the signal intensity is higher than when tandem mass spectrometry is performed alone, and the detection sensitivity is improved.

  The fragment mass spectrum (not shown) obtained in Example 3 has the same pattern as the fragment mass spectrum shown in FIG. 10, but the signal intensities at m / z = 46 and 92 were high.

  In Example 4, an explosive detection device using a wipe material impregnated with lactic acid will be described.

  FIG. 11 is a diagram illustrating a configuration example of the explosives detection apparatus according to the fourth embodiment of the present invention. In the apparatus shown in FIG. 11, an impregnated wipe material was used.

  As shown in FIG. 11, the apparatus includes a suction unit 1 (upper heater) and a heater 2 including a lower heater, an ion source 4, a mass analyzer 5, and a data processor 6. In the ion source 4, approximately 0.5 L / min is sucked by the suction pump 10 and the suction mass flow controller 11 in order to suck the vapor or fine particles of the sample introduced from the suction unit 1.

  For example, 0.1 μg of lactic acid is included in the impregnated wipe material 38 in advance. The amount of lactic acid may be an amount that can generate sufficient lactic acid gas to detect lactic acid addition ions. Further, a wiping material containing lactic acid may be used without impregnating lactic acid. For example, since natural cellulose is used for cotton or the like, it contains a small amount of lactic acid. You may utilize the lactic acid contained in the raw material of these wipe materials.

  Even when a wipe material that does not contain lactic acid at all is used, a small amount of lactic acid attached to the baggage may be wiped off when the baggage is wiped off. This is because lactic acid is often used in many cosmetics, and the components of this cosmetic and the lactic acid component from the human body adhere to the baggage and are wiped off with a wipe material, which is transferred to the wipe material and impregnated with lactic acid. It will be the same as the state you let it.

  In the inspection, the baggage is wiped with the impregnated wipe 38 and a very small amount of explosive component is collected. The impregnated wipe material 38 is inserted into the heater 2 including the suction unit 1 (upper heater) and the lower heater. The upper heater and the lower heater are only required to be maintained at a temperature at which the collected sample evaporates. For example, both the upper and lower heaters were heated at 210 ° C. When the wipe material 12 is inserted, the lower heater is raised, and the wipe material 12 is heated to evaporate the explosive sample. At that time, lactic acid contained in the impregnated wipe material is gasified, mixed with the sample gas, and becomes a mixed gas. The mixed gas passes through the heated filter 13 (for example, heated at 210 ° C.) and the pipe 14 (for example, heated at 180 ° C.) heated by the pipe heater 15, and then the ion source 4. To be introduced. In the ion source 4, the mixed gas is ionized and the mass analysis unit 5 performs mass analysis.

  The obtained mass spectrum is sent to the data processing unit 6 to determine the presence or absence of a specific m / z ion peak generated from the detection target substance to be detected, and if detected, an alarm is sounded. . Furthermore, even if a specific m / z ion peak generated from the substance to be detected is not detected, it is detected by determining the presence or absence of a specific m / z ion peak added by a molecule generated from lactic acid. If an alarm occurs, an alarm will sound.

  That is, when either an m / z ion peak of a molecule generated from a detection target substance or a specific m / z ion peak obtained by adding a molecule generated from lactic acid to the detection target substance is detected, An alarm may be sounded. By repeating these operations, it functions as an explosive detection device.

  In the fifth embodiment, an explosive detection device using a suction method using an organic acid gas generator will be described.

  FIG. 12 is a diagram illustrating a configuration example of the explosives detection apparatus according to the fifth embodiment of the present invention. In the apparatus shown in FIG. 12, a sample was collected by a suction method and an organic acid gas generator was used.

  As shown in FIG. 12, the apparatus includes a suction port 39, an organic acid gas generator 3, an ion source 4, a mass analyzer 5, and a data processor 6. About 400 μL of lactic acid, which is an example of an organic acid, is placed in the organic acid gas generator 3 and heated to about 40 ° C. by the generator heater 9 to generate lactic acid vapor. Further, it is introduced into the ion source 4 at a flow rate of about 0.1 L / min by the extrusion pump 7 and the extrusion mass flow controller 8. In that case, the extrusion flow rate should just be a flow rate which does not flow backward to the suction part side. In the ion source 4, about 0.5 L / min is exhausted by the intake pump 10 and the intake mass flow controller 11 in order to suck the vapor or fine particles of the sample inserted from the suction port 39. Since there are pores through which ions pass between the ion source 4 and the mass analysis unit 5 and the gas is exhausted by the vacuum pump of the mass analysis unit 5 at about 0.5 L / min, the sample gas sucked into the suction unit 1 Is sucked at about 0.9 L / min.

  In the inspection, fine particles or vapor of explosive adhering to a human body or baggage is sucked from the suction port 39. At this time, explosive fine particles and vapor may be sucked by a blown gas such as air. In addition, the suction port may be provided with a concentrator such as a filter, and may be provided with a mechanism that once captures fine particles and vapor of the explosive and heats and evaporates them. Aside from the intake pump 10, the suction port concentrator may be provided with a large-capacity pump and a mechanism for capturing explosive fine particles and vapor at a time.

  The suction port 39 only needs to be maintained at a temperature at which the collected sample evaporates, and is heated at 210 ° C., for example. In addition, a mechanism is provided to maintain a distance so that the heating unit does not directly contact a human body or baggage. The sucked sample passes through a heated filter 13 (for example, heated at 210 ° C.) and a pipe 14 (for example, heated at 180 ° C.) heated by a pipe heater 15, and is then treated with an organic acid. The lactic acid vapor generated in the gas generator 3 is mixed with the mixing unit 16 and introduced into the ion source 4. In the ion source 4, the mixed gas is ionized and the mass analysis unit 5 performs mass analysis.

  The obtained mass spectrum is sent to the data processing unit 6 to determine the presence or absence of a specific m / z ion peak generated from the detection target substance to be detected, and if detected, an alarm is issued. Sound. Furthermore, even if a specific m / z ion peak generated from the substance to be detected is not detected, it is detected by determining the presence or absence of a specific m / z ion peak added by a molecule generated from lactic acid. If an alarm occurs, an alarm will sound.

  That is, when either an m / z ion peak of a molecule generated from a detection target substance or a specific m / z ion peak obtained by adding a molecule generated from lactic acid to the detection target substance is detected, An alarm may be sounded. By repeating these operations, it functions as an explosive detection device.

  In each of the above examples, lactic acid was used as the organic acid dopant, but in Example 6, the results of using another organic acid or organic acid salt as the dopant will be described.

  First, an example using succinic acid as an organic acid dopant will be described.

  FIG. 13 is a diagram showing a mass spectrum of explosive RDX obtained when succinic acid is introduced as a dopant into the apparatus in Example 6 of the present invention.

  Succinic acid is an organic acid containing a hydroxyl group and a carboxyl group similar to lactic acid. Furthermore, there is a feature that the mass number of succinic acid (mass number 118) is larger than lactic acid (mass number 90). About 400 μL of succinic acid was placed in the organic acid gas generator 3 to generate succinic acid gas. Explosive RDX 50 ng was dropped onto the wipe material and inserted into the heater 2. A unique molecular ion (succinic acid-derived ion) generated from succinic acid was detected at m / z = 117. This is presumed to be a hydrogen desorption ion of succinic acid.

  Furthermore, a succinic acid addition ion (an RDX succinic acid-derived additional ion) added by a molecule generated from succinic acid to RDX is detected at m / z = 338. This m / z = 338 is set as a detection target. Therefore, an organic acid addition ion is generated even in an organic acid having a mass number larger than that of lactic acid. Moreover, since the mass number of main explosives is about 400 or less, it is better to use the organic acid having a mass number of about 40 to 400. This is because when the molecular weight of the organic acid is too large, the vapor pressure is lowered and it is difficult to generate gas, and too large molecular ions are difficult to generate additional ions with the explosive.

  Next, examples using butyric acid as an organic acid dopant will be described.

  FIG. 14 is a diagram showing a mass spectrum of explosive RDX obtained when butyric acid is introduced into the apparatus as a dopant in Example 6 of the present invention.

  Butyric acid is an organic acid containing a hydroxyl group and a carboxyl group in the same manner as lactic acid. The mass numbers of lactic acid (mass number 90) and butyric acid (mass number 89) are substantially the same. About 400 μL of butyric acid was added to the organic acid gas generator 3 to generate butyric acid gas. Explosive RDX 50 ng was dropped onto the wipe material and inserted into the heater 2. A unique molecular ion (butyric acid-derived ion) generated from butyric acid was detected at m / z = 89. Furthermore, butyric acid adduct ions (RDX butyric acid-derived adduct ions) in which molecules generated from butyric acid are added to RDX are detected at m / z = 310. This m / z = 310 is set as a detection target.

  Next, an example using sodium lactate in which lactic acid is converted to a salt as an example of an organic acid salt will be described.

  FIG. 15 is a diagram showing a mass spectrum of explosive RDX obtained when sodium lactate is introduced into the apparatus as a dopant in Example 6 of the present invention.

  The mass number of sodium lactate is 112, which is larger than lactic acid (mass number 90). About 400 μL of sodium lactate was placed in the organic acid gas generator 3 to generate sodium lactate gas. Explosive RDX 50 ng was dropped onto the wipe material and inserted into the heater 2. A unique molecular ion (sodium lactate-derived ion) generated from sodium lactate was detected at m / z = 89.

  Further, this sodium lactate addition ion (addition ion derived from RDX sodium lactate) in which a molecule generated from sodium lactate is added to RDX is detected at m / z = 310. This m / z = 310 is set as a detection target. This may be due to the fact that sodium lactate is thermally decomposed by heating into lactic acid gas. Therefore, even when an organic acid or organic acid salt having a molecular weight of 40 to 400 is used, the organic acid or organic acid salt is thermally decomposed, and the organic acid molecule generates an additional ion of the detection target substance.

  According to the chemical substance detection apparatus of the present invention, environmental substances, harmful chemical substances, narcotics, and explosives are detected by detecting ions generated by reaction with molecules generated from organic acids or organic acid salts. Is possible

DESCRIPTION OF SYMBOLS 1 ... Suction part (upper heater), 2 ... Heater, 3 ... Organic acid gas generator, 4 ... Ion source, 5 ... Mass analysis part, 6 ... Data processing part, 7 ... Extrusion pump, 8 ... Extrusion mass flow controller DESCRIPTION OF SYMBOLS 9 ... Generator heater, 10 ... Intake pump, 11 ... Intake mass flow controller, 12 ... Wipe material, 13 ... Filter, 14 ... Pipe, 15 ... Pipe heater, 16 ... Mixing part, 17 ... Needle electrode, 18 ... Counter electrode 19 ... Electrode with pores (first pore), 20 ... First pore, 21 ... Differential exhaust part, 22 ... Electrode with pores (second pore), 23 ... Second pore, 24 ... 1st exhaust system, 25 ... 2nd exhaust system, 26 ... vacuum part, 27 ... end cap electrode a, 28 ... end cap electrode b, 29 ... ring electrode, 30 ... ion focusing lens, 31 ... quartz ring, 32 ... gas Feeder 33 ... gas introduction pipe 34 ... conversion electrode 3 ... scintillator, 36 ... photomultiplier 37 ... data processing unit, 38 ... impregnated wipes, 39 ... suction port.

Claims (3)

A heating unit for generating a sample gas;
An organic acid source having an organic acid or an organic acid salt having a mass number of 40 or more and 400 or less;
A gas generator for generating a gas of the organic acid or organic acid salt from the organic acid source;
A gas mixing unit that mixes the gas of the organic acid or the organic acid salt with the gas of the sample generated in the heating unit to generate a mixed gas;
An ion source characterized in that, from the mixed gas, ions obtained by adding ions derived from the organic acid or ions derived from the organic acid salt to molecules of the sample are generated.   The ion source according to claim 1, wherein the organic acid or the organic acid salt is an organic acid or organic acid salt having a hydroxyl group or a carboxyl group, or lactic acid or a lactate.   The ion source according to claim 1, wherein the organic acid source is a wiping member impregnated with the organic acid or organic acid salt.

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