JP2007010683A - Detection method and detection system using ion trap mass spectrometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detection system for explosive substances, banned drugs and the like, which operates with less false reports at a high speed, by using a high-speed screening mode and a high-selective detail checking mode at the same time. <P>SOLUTION: In a detection method using a mass spectrometer, the screening is carried out at a high speed by using a step (201) of acquiring a mass spectrum and a step (202) of determining whether or not an intrinsic m/z ion exists, and then an analysis condition is read from a database in accordance with a determination result of the determining step (202), and changing to a step (203) of conducting a tandem mass spectrometry is carried out in order to check details. Then, a step (204) of determining whether or not the intrinsic m/z ion exists, is carried out based on a result obtained by the tandem mass spectrometry. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a technique for detecting explosives and drugs, and more particularly to a detection apparatus using a mass spectrometer.

  As international conflicts become more serious, detection devices for detecting explosives are required to prevent terrorism and maintain security. In detection devices, baggage inspection devices using X-ray transmission are widely used mainly in airports. An X-ray detection apparatus or the like recognizes an object as a lump and discriminates a dangerous substance from information such as a shape, so is called bulk detection. On the other hand, a detection method based on gas analysis is called trace detection, and identifies a substance from chemical analysis information. Trace detection is characterized by the ability to detect trace components attached to bags and the like. As social security is demanded, a device that detects dangerous objects with higher accuracy by combining bulk detection and trace detection is desired.

On the other hand, detection devices are also used by customs to find forbidden drugs brought in by various routes. In customs, bulk detectors and drug detection dogs are mainly used, but trace analysis devices for forbidden drugs that replace drug detection dogs are eagerly desired.
In trace detection, various analysis methods such as ion mobility spectroscopy and gas chromatography have been tried. Research is progressing toward the development of a device that has all the speed, sensitivity, and selectivity that are important as detection devices.

  Under such circumstances, mass spectrometry is basically excellent in speed, sensitivity, and selectivity. For example, a detection technique based on mass spectrometry has been proposed as disclosed in JP-A-7-134970. ing. A conventional detection device based on mass spectrometry will be described with reference to FIG.

The air intake probe 1 is connected to an ion source 3 through an insulating pipe 2, and the ion source 3 is connected to an air exhaust pump 6 through an exhaust port 4 and an insulating pipe 5. The ion source 3 includes a needle electrode 7, a first pore electrode 8, an intermediate pressure portion 9, and a second pore electrode 10, and the needle electrode 7 is connected to a power source 11, and the first pore electrode 8 and the second pore electrode 10 are connected. The hole electrode 10 is connected to an ion acceleration power source 12. The intermediate pressure unit 9 is connected to a vacuum pump through the exhaust port 13. The electrostatic lens 14 is disposed downstream of the intermediate pressure unit, and the mass analyzer 15 and the detector 16 are disposed downstream of the electrostatic lens 14. A detection signal from the detector 16 is supplied from the amplifier 17 to the data processing unit 18. The data processing unit 18 determines a plurality of m / z (ion mass number / ion valence) values indicating a specific drug, and determines whether or not the specific gas is contained in the test gas.
The data processing unit 18 includes a mass determination unit 101, a drug A determination unit 102, a drug B determination unit 103, a drug C determination unit 104, and an alarm driving unit 105. Display units 106, 107, and 108 are arranged on the alarm display unit 19 driven by the alarm driving unit 105.

JP-A-7-134970

The above prior art has the following problems.
In the above apparatus, the drug determination is performed using the m / z value of ions generated by the ion source. Therefore, when there is a chemical substance that generates ions having the same m / z as the drug being detected, there is a high possibility of false alarms such as displaying an alarm despite the absence of the drug.

More specifically, when detecting a stimulant in the baggage, there is a problem that a false alarm is generated in response to a cosmetic component contained in the baggage. This is because the selectivity of the mass spectrometer for analyzing ions is low, and it happens because the ions derived from the stimulant having the same m / z by chance cannot be distinguished from the ions derived from the cosmetics.
Tandem mass spectrometry is known as a method for enhancing selectivity in a mass spectrometer.
Examples of apparatuses for performing tandem mass spectrometry include a triple quadrupole mass spectrometer and a quadrupole ion trap mass spectrometer.
In tandem mass spectrometry, usually
(1) First-stage mass spectrometry mass spectrometry is performed, and m / z of ions generated by the ion source is measured.
(2) Selection An ion having a specific m / z is selected from ions having various m / z.
(3) Dissociation-selected ions (precursor ions) are dissociated by collision with a neutral gas or the like to generate decomposition product ions (fragment ions).
(4) Mass analysis of the second stage mass analysis fragment ions.
The steps are used. 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 analyzing fragment ions, a mass spectrum containing abundant molecular structure information of precursor ions can be obtained. Therefore, even if the m / z of ions generated by the ion source is coincidentally the same, it is possible to determine whether or not an object to be detected is included by examining the mass spectrum of the fragment ions.

Therefore, in the conventional detection apparatus shown in FIG. 16, if the mass analyzer 15 is replaced with a triple quadrupole mass spectrometer or a quadrupole ion trap mass spectrometer and tandem mass spectrometry is performed, the selectivity is improved. Improve and reduce false alarms. However, since tandem mass spectrometry takes longer time than ordinary mass spectrometry, there is a problem that the detection speed required for the detection device cannot be achieved.
For the above reasons, a detection device having both high selectivity and high detection speed has been desired.

An object of the present invention is to provide a high-speed detection mode for detecting explosives and forbidden drugs, etc. with a high speed and few false alarms by using both a high-speed screening mode and a high-selectivity scrutiny mode.

The analysis method of the present invention includes a first analysis step for acquiring a mass spectrum, a first determination step for determining whether or not a first intrinsic m / z ion exists, and a determination result of the first determination step. And a second analysis step of performing tandem mass spectrometry according to the analysis conditions. A first analysis step for acquiring an ^n- th order (MS ⁿ ) mass spectrum, a first determination step for determining whether a first intrinsic m / z ion exists, and a first determination step The method includes a step of reading analysis conditions from a database according to the determination result, and a second analysis step of performing ( ^{n + 1} ) ^-th (MS ^{n + 1} ) mass analysis according to the analysis conditions. Furthermore, in the analysis method using a mass spectrometer, the method includes a step of dissociating ions having a wide range of m / z, a step of performing mass analysis, and a determination step of determining whether ions of a specific m / z are present. It is characterized by that.

As described above, according to the present invention, detection with high speed and high selectivity is possible, and the presence or absence of a target substance can be examined without hindering the flow of luggage or people.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram for explaining an algorithm according to an embodiment of the present invention.
In the present embodiment, a first analysis step 201 for acquiring a mass spectrum, a first determination step 202 for determining whether or not a first unique m / z ion exists, and the first determination step 202 A second analysis step 203 for performing tandem mass spectrometry according to the determination result, a second determination step 204 for determining whether or not a second specific m / z ion exists, and the second determination step A notification step 205 for issuing an alarm according to the determination result 204 is provided. The measurement operation at step 201 and step 202 is set as a screening mode, and the measurement operation at step 203 and step 204 is set as a close examination mode.
When performing detection, ions generated from the sample gas are analyzed in step 201, and it is determined in step 202 whether or not ions having m / z corresponding to ions derived from the detection target are detected. For example, when amphetamine, which is a kind of stimulant, is ionized in the positive atmospheric pressure chemical ionization mode, a pseudo-molecular ion (M + H) + (M is a sample molecule and H is a proton) in which a proton is added to an amphetamine molecule is generated. Since m / z of the pseudo molecular ion is 136, it is determined in step 202 whether or not an ion having m / z of 136 is detected. (First judgment)
Here, it goes without saying that the value of m / z determined in step 202 differs depending on the detection target. A plurality of different m / z values may be determined corresponding to various narcotics, stimulants and the like.
When the analysis time in the first analysis step 201 is set to 0.1 second, the step 201 may be repeated, and the measurement results may be accumulated and then the accumulated result may be determined by the step 202. Since the random noise is averaged by the integration, the erroneous determination ratio in step 202 can be reduced.

In step 202, if it is determined that there is an ion having a first inherent m / z that is set in advance, a second analysis that performs tandem mass spectrometry (hereinafter referred to as MS / MS) Step 203 is executed. Step 203 includes selection of precursor ions, dissociation of precursor ions, and mass analysis of fragment ions. In order to improve the accuracy of analysis, it is better to spend a longer time in step 203 than in step 201.
In step 203, a mass spectrum rich in molecular structure information is obtained. This mass spectrum is determined in step 204 (second determination), and it is determined whether or not an ion having m / z peculiar to the detection target exists. If present, an alarm is activated and notified in step 205.
When the determination is made in step 204, a mass spectrum obtained by tandem mass spectrometry of the detection target object is measured in advance and used as a database, and a highly accurate determination can be made by referring to this database.
More specifically, the detection method using the algorithm shown in FIG. 1 is as follows. During detection, a screening mode (that is, measurement in step 201 and determination in step 202) is first executed, and this is repeated. When the time required for step 201 is set to 0.1 seconds, and the measurement results obtained by accumulating 10 measurements are determined in step 202, the total detection time is about 1 second. If it is suspected that the detection target exists by the determination in step 202, the mode is shifted to the scrutiny mode. If the time required for step 203 is 0.5 seconds and the measurement results of 10 times are added and then determined in step 204, the total detection time is about 6 seconds including the screening mode starting from step 201.

In the case of a baggage inspection accompanying a security gate or the like, it is usually necessary to carry out the inspection in several seconds including carrying in the baggage into the detection device, detecting the baggage from the detection device, and taking out the baggage from the detection device. Therefore, although the actual time that can be spent for detection is 1 to 2 seconds, it is assumed that there is no detection object in most baggage, so the detection can be completed in about 1 second by the screening mode. I can do it. Therefore, by using the algorithm shown in Fig. 1, the average time required for detection can be reduced to about 1 to 2 seconds per bag even if it takes a long time to reach the scrutiny mode. , Baggage can be inspected at the security gate without significantly obstructing the flow of luggage. Moreover, since the determination based on the tandem mass spectrometry is finally performed in the scrutiny mode, the selectivity is high and the false alarm can be reduced.
As described above, since it takes time to scrutinize by tandem mass spectrometry, when the process proceeds to step 203 as a result of the determination in step 202, that is, when the screening mode is switched to the scrutinization mode, a warning lamp is turned on at this stage. It is preferable to output a signal that is easy for the operator to recognize, such as lighting.

  FIG. 2 is a diagram showing a specific apparatus configuration for carrying out the present invention. An example in which a quadrupole ion trap mass spectrometer (hereinafter referred to as an ion trap mass spectrometer) is used for the mass analyzer is shown. A gas introduction pipe 21 and exhaust pipes 22 a and 22 b are coupled to the ion source 20. The gas from the sample gas collection port is sucked by a pump coupled to the exhaust pipes 22 a and 22 b and introduced into the ion source 20 through the gas introduction pipe 21. A part of the components contained in the gas introduced into the ion source is ionized. The ions generated by the ion source and a part of the gas introduced into the ion source are transferred to the vacuum unit 27 exhausted by the vacuum pump 26 through the first pore 23, the second pore 24, and the third pore 25. It is captured. These pores have a diameter of about 0.3 mm, and the electrode in which the pores are opened is heated from about 100 ° C. to about 300 ° C. by a heater (not shown). The gas that has not been taken in from the first pores 23 is exhausted from the exhaust pipes 22a and 22b to the outside of the apparatus via a pump.

Between the electrodes in which the pores 23, 24, and 25 are opened, differential exhaust portions 28 and 29 are exhausted by the roughing pump 30. As the roughing pump 30, a rotary pump, a scroll pump, a mechanical booster pump, or the like is usually used. However, a turbo molecular pump can be used for exhaust in this region. In addition, a voltage can be applied to the electrodes in which the pores 23, 24, and 25 are opened, and at the same time, the ion permeability is improved, and at the same time, the cluster ions generated by adiabatic expansion are collided with the remaining molecules. Perform cleavage.
In FIG. 2, a scroll pump having a pumping speed of 900 liters / minute is used as the roughing pump 30, and a turbo molecular pump is used as the vacuum pump 26 evacuating the vacuum part 27. The roughing pump 30 is also used as a pump for exhausting the back pressure side of the turbo molecular pump. The pressure between the second pore 24 and the third pore 25 is about 1 Torr. It is also possible to remove the electrode opened by the second pore 24 and to make a differential exhaust part composed of two pores, the first pore 24 and the third pore 25. However, since the amount of gas flowing in increases as compared with the above case, it is necessary to devise measures such as increasing the exhaust speed of the vacuum pump to be used and increasing the distance between the pores. Also in this case, it is important to apply a voltage between both pores.
The generated ions are converged by the converging lens 31 after passing through the third pore 25. As the converging lens 31, an Einzel lens usually composed of three electrodes is used. The ions further pass through the slit electrode 32. A structure in which ions that have passed through the third pore 25 converge and pass through the opening of the slit electrode 32 by the converging lens 31, but neutral particles that are not converged collide with the slit portion and do not easily reach the mass analysis unit side. It has become. The ions that have passed through the slit electrode 32 are deflected and converged by a double cylindrical deflector 35 including an inner cylinder electrode 33 and an outer cylinder electrode 34 having a large number of openings. The double cylindrical deflector 35 deflects and converges using the electric field of the outer cylinder electrode that has oozed out from the opening of the inner cylinder electrode. Details of this have already been disclosed in JP-A-7-85834.

The ions that have passed through the double cylindrical deflector 35 are introduced into an ion trap mass spectrometer composed of a ring electrode 36 and end cap electrodes 37a and 37b. The gate electrode 38 is provided for controlling the timing of ion incidence to the mass spectrometer. The collar electrodes 39a and 39b are provided to prevent ions from reaching the quartz rings 40a and 40b holding the ring electrode 36 and the end cap electrodes 37a and 37b and charging the quartz rings 40a and 40b.
Inside the ion trap mass spectrometer, helium is supplied from a helium gas supply pipe (not shown) and maintained at a pressure of about 10 −3 Torr. The ion trap mass spectrometer is controlled by a mass spectrometer controller (not shown). Ions introduced into the mass spectrometer collide with helium gas, lose energy, and are captured by an alternating electric field. The trapped ions are ejected out of the ion trap mass spectrometer according to the ion m / z by scanning the high frequency voltage applied to the ring electrode 36 and the end cap electrodes 37a and 37b, and the ion extraction lens. It is detected by the detector 42 via 41. The detected signal is amplified by the amplifier 43 and then processed by the data processing device 44.
Since the ion trap mass spectrometer has a characteristic of trapping ions inside (a space surrounded by the ring electrode 36 and the end cap electrodes 37a and 37b), when the concentration of the detection target substance is low and the amount of ions generated is small However, it can be detected by increasing the ion introduction time.
Therefore, even when the sample concentration is low, the ion can be concentrated at high magnification in the ion trap mass spectrometer, and the sample pretreatment (concentration, etc.) can be greatly simplified.

  FIG. 3 is an enlarged view of the ion source portion of the apparatus shown in FIG. The gas introduced through the sample gas introduction pipe 21 is once introduced into the ion drift portion 45. The ion drift portion 45 is almost at atmospheric pressure. A part of the sample gas introduced into the ion drift part 45 is introduced into the corona discharge part 46, and the rest is discharged out of the ion source through the exhaust pipe 22b. The sample gas introduced into the corona discharge part 46 is introduced into the corona discharge region 48 generated near the tip of the needle electrode 47 by applying a high voltage to the needle electrode 47 and ionized. At this time, in the corona discharge region 48, the sample gas is introduced in a direction substantially opposite to the flow of ions drifting from the needle electrode 47 toward the counter electrode 49. The generated ions are introduced into the ion drift portion 2 through the opening 50 of the counter electrode 49 by an electric field. At this time, by applying a voltage between the counter electrode 49 and the electrode in which the first pore 23 opens, ions can be drifted and efficiently guided to the first pore 23. The ions introduced from the first pores 23 are introduced into the vacuum part 27 through the second pores 24 and the third pores 25.

The flow rate of the gas flowing into the corona discharge part 46 is important for detecting with high sensitivity and stability.
For this reason, it is good to provide the flow control part 51 in the exhaust pipe 22a. Moreover, the drift part 45, the corona discharge part 46, the gas introduction tube 21 and the like are preferably heated by a heater (not shown) or the like from the viewpoint of preventing the adsorption of the sample. The flow rate of gas passing through the gas introduction pipe 21 and the exhaust pipe 22b can be determined by the capacity of the suction pump 52 such as a diaphragm pump and the conductance of the pipe, but the gas introduction pipe 21 and the exhaust pipe 22b are also shown in FIG. A control device such as the flow rate control unit 51 shown in FIG. By providing the suction pump 52 downstream of the ion generation unit (that is, the corona discharge unit 46 in the illustrated configuration) when viewed from the gas flow, the influence of contamination (such as sample adsorption) inside the suction pump 52 is reduced. Become.

FIG. 4 is a diagram showing an example of a sample gas sampling unit of the apparatus according to the present invention. The detection device is roughly divided into a main body 53, a gas suction unit 54, a housing 55, and a data processing device 44.
The gas inlet tube 21 connected to the probe 56 is used as the gas suction unit 54, and the probe 56 is brought close to the baggage or the like to suck the air around the baggage into the main body 53 and perform detection.
For reference, in order to explain the operation of the ion trap mass spectrometer in one embodiment of the present invention, FIGS. 5 and 6 show timings of voltages applied to the ring electrode and the end cap electrode. FIG. 5 shows the operation in step 201 in FIG. 1, and FIG. 6 shows the operation in step 203.

  In step 201, at the time of ion confinement 302, a high frequency is applied to the ring electrode to generate an electric field for trapping ions in the mass spectrometer. In addition, the voltage applied to the gate electrode is adjusted so that ions pass through the gate electrode and are introduced into the mass spectrometer. Next, at the time of mass spectrometry 303, the voltage applied to the gate electrode is adjusted in order to prevent further inflow of ions. By manipulating the amplitude of the high frequency applied to the ring electrode and end cap electrode, ions with different m / z are sequentially discharged out of the mass spectrometer from the ions trapped inside by the electric field and detected by the detector. A mass spectrum is obtained. Next, a residual ion removal time 301 is provided, and ions remaining in the mass spectrometer are removed by turning off the voltage applied to the ring electrode.

  Typically, the ion confinement time 302 is 0.04 seconds, the mass analysis time 303 is 0.05 seconds, the residual ion removal time 301 is 0.01 seconds, and a mass spectrum is acquired once in 0.1 seconds. I can do it. If the sample concentration is low and high sensitivity is required, the ion confinement time 302 may be further increased.

  Next, the operation in step 202 will be described with reference to FIG. The operations at the time of ion confinement 302 and at the time of mass analysis 303 are the same as in step 201. In the selection time 304, an operation is performed in which ions having a predetermined m / z are left out of various ions confined in the ion confinement time 203 and other ions are excluded. In this selection time 304, for example, a filtered noise field disclosed in Rapid Communications in Mass Spectrometry, Vol. 7, page 1086 (1993) can be used. In the dissociation time 305, energy is given to the ions having the determined m / z selected in the selection time 304, and collides with helium gas or the like in the mass spectrometer to generate fragment ions. To energize the ions, a high frequency is applied between the end cap electrodes and the ions are accelerated in the mass spectrometer. The accelerated ions collide with a gas such as helium, but at that time, part of the kinetic energy of the ions is converted into the internal energy of the ions, and the internal energy accumulates as the collision repeats, and the chemistry in the ions The weak part of the bond is cut and dissociation occurs.

  In tandem mass spectrometry, ions are lost during selection and dissociation, so that a sufficient amount of ions must be confined at the time of ion confinement 302 in order to obtain a good mass spectrum of fragment ions. Therefore, typically, the ion confinement time 302 is 0.40 seconds, the mass analysis time 303 is 0.05 seconds, the selection time 304 is 0.03 seconds, the dissociation time 305 is 0.01 seconds, and the residual ion removal time. 301 is set to 0.01 seconds, and a mass spectrum is acquired once in 0.5 seconds.

In the analytical field, mass spectrometry is used for various applications. However, when mass spectrometry is used for the detection device, the situation differs from that of normal analysis.
First, while an ordinary analysis targets a very large number of components, the detection device targets a very limited substance. For example, since a bomb is created by mixing various explosives, it is possible to find a bomb by selecting and detecting several main explosives. Further, in normal analysis, the concentration of a substance is quantified, but it is sufficient that the presence or absence of an object can be determined at the time of detection.

  Therefore, an operation method of the mass spectrometer particularly effective in the detection device will be described with reference to FIG. In the ion trap mass spectrometer, when the trapped ions are extracted to the outside, the extraction efficiency varies depending on the speed of mass scanning. That is, if the increase rate of the amplitude applied to the ring electrode is increased at the analysis time 303 in FIG. 5 and the analysis time 303 is set to end in a short time, it is taken out of the mass spectrometer and reaches the detector. Since the amount of ions increases, there is an advantage that sensitivity is improved. However, if the amplification factor of the amplitude applied to the ring electrode at the analysis time 303 is increased, the mass resolution is lowered, or ions are not ejected at a predetermined timing, so that the measured m / z deviates from the correct value. was there. Therefore, as shown in FIG. 7, when the ion trap mass spectrometer is operated, the ion confinement step 206 (corresponding to the ion confinement time 302) and the ion discharge step 208 (corresponding to the analysis time 303) are performed. Step 207 (corresponding to selection time 307) for selecting specific ions was provided. That is, it is important to compensate for the reduction in resolution caused by mass scanning at high speed by limiting the m / z of ions remaining in the mass spectrometer in advance. Specifically, when detecting amphetamine, the first thing to check is a positive ion whose m / z is 136. Therefore, the ions generated in the ion source are confined in the mass spectrometer in step 206, and then in step 207, ions having a value other than 136 are excluded, and ions having m / z of 136 are selectively selected. To remain. Next, mass scanning is performed at a high speed in step 208 of ion ejection, and ions remaining in the mass spectrometer are efficiently drawn out of the mass spectrometer. By doing so, it is clear that the m / z of ions reaching the detector is 136, so that it is not necessary to perform precise mass selection in step 208, and the analysis time can be shortened and the sensitivity is good. Detection becomes possible. This method is effective not only at the time of screening but also when scrutinizing by tandem mass spectrometry. As shown in FIG. 8, a step 210 for selecting m / z of ions remaining in the mass spectrometer can be provided between the step 209 for performing dissociation and the step 208 for discharging ions.

  Furthermore, since the types of objects to be detected are limited, it is very effective to construct a database related to the objects on the data processing apparatus and perform the detection while referring to this database. More specifically, when performing tandem mass spectrometry, the optimum values such as the length of the dissociation time and the amplitude of the high frequency applied to the end cap electrode in order to give energy to the ions during the dissociation vary depending on the target chemical substance. Therefore, as shown in FIG. 9, the optimal analysis conditions for each component to be detected are examined in advance and made into a database, and when the presence of a specific substance is suspected in the high-speed mode, when moving to the scrutinization mode A step 211 for reading the optimum analysis conditions for the substance with reference to the database is provided. By doing in this way, the favorable mass spectrum of a fragment ion is obtained and it can determine with a sufficient precision. For example, for various forbidden drugs such as amphetamine and cocaine, the optimal analysis conditions for each of these drugs are investigated and a database is created. In such a case, it is better to call the analysis conditions for cocaine and analyze it.

  As described above, the method of ionizing the detection target substance and screening based on the ion m / z has been described. However, the screening can be performed without necessarily specifying the ion m / z by mass separation. A second embodiment of the present invention in which screening is performed based on ion current values will be described with reference to FIGS. FIG. 10 shows the timing of the high frequency applied to the ring electrode and end cap electrode. As shown in FIG. 6, an ion confinement time 302 and an ion selection time 304 may be provided in this order, but in FIG. 10, confinement / selection times 302 and 304 for simultaneously performing ion confinement and selection are provided. FIG. 11 shows the frequency of the high frequency applied to the end cap electrode at the confinement / selection times 302 and 304. Ions trapped inside the ion trap mass spectrometer have a frequency that tends to resonate according to their m / z. Therefore, if a signal that does not include frequencies (f1, f2, and f3) corresponding to m / z of ions of the substance to be detected and includes other frequency components is applied, the confinement / selection times 302 and 304 are focused. Only ions with m / z to be trapped. Next, an ion discharge time 306 is provided, and ions remaining in the mass spectrometer are discharged and detected by a detector. Here, when any signal is obtained, it is only necessary to issue an alarm and shift to a more detailed examination mode. In this method, time required for mass spectrometry is not required, so that screening can be performed at a higher speed. Next, a third embodiment of the present invention effective for detecting explosives will be described with reference to FIGS. This is a screening method using ions derived from nitro groups obtained by dissociating explosives. Nitro compounds tend to decompose when energy is applied, and the nitro group tends to dissociate. Therefore, as shown in FIG. 12, confinement / dissociation times 302 and 305 for simultaneously performing ion confinement and dissociation are provided. FIG. 13 shows the frequency of the high frequency applied to the end cap electrode during the confinement / dissociation times 302 and 305. While the signal includes frequencies (f1, f2, f3) corresponding to m / z of ions of the substance to be detected and does not include the frequency (f4) corresponding to m / z of ions derived from the nitro group to be detected. Applied to the end cap electrode. When ions of explosives to be detected are confined, they resonate due to the high frequency applied to the end cap electrode, and are given energy to collide with a gas such as helium. Since the nitro group is dissociated at this time, the screening can be performed by detecting the ion derived from the dissociated nitro group, for example, NO2− at the analysis time 303. The advantage of this method is that even if a nitro compound other than the substance to be detected is included, the dissociated nitro group is detected, so that it can be discovered.

  In the method described above, in order to further improve the selectivity, higher-order mass spectrometry may be performed as shown in FIG. That is, there is provided a step 212 (which is called MS / MS / MS or MS3) for selecting an ion having a specific m / z from fragment ions and mass-analyzing the ion obtained by dissociating the ion. Also good. Such processes of selection, dissociation, and mass spectrometry can be repeated until selectivity is satisfied (generally referred to as MSn).

  In the present invention, the time required for detection differs between high-speed screening and detailed examination. Therefore, as shown in FIG. 15, the detection device according to the present invention may be used in combination with the baggage transport device 57. The transport device 57, the transport device control device 58, and the detection device main body 53 are connected by signal lines 59a and 59b. At the time of screening, the conveyance is performed at a constant speed. However, when the main body 53 is switched to the scrutinizing mode and detection is performed over a period of several seconds, it is preferable to perform control such as reducing the conveyance speed of the conveyance device 57.

It is a figure which shows the algorithm of one Example of this invention. It is a figure which shows an example of the apparatus structure for implementing this invention. It is a figure which shows an example of a structure of the ion source part for implementing this invention. It is a figure which shows an example of a structure of the vapor | steam extraction part for implementing this invention. It is a figure which shows the timing of the voltage application in one Example of this invention. It is a figure which shows the procedure of MS / MS analysis in one Example of this invention. It is a figure which shows the procedure of the analysis in one Example of this invention. It is a flowchart figure which shows a tandem mass spectrometry. It is a figure which shows the algorithm of one Example of this invention. It is a figure which shows the timing of the high frequency voltage applied to a ring electrode and an end cap electrode. It is a figure which shows the frequency of the voltage with which the end cap electrode was applied in the confinement selection time. It is a figure which shows the condition where ion confinement and dissociation advance simultaneously in one Example of this invention. It is a figure which shows the frequency of the high frequency voltage applied to the end gap electrode when ion confinement and dissociation advance simultaneously in one Example of this invention. It is a figure which shows the algorithm of one Example of this invention. It is a figure which shows the apparatus structure of one Example of this invention. It is a figure which shows the structure of the conventional mass spectrometer used for a dangerous material detection.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 20 ... Ion source, 21 ... Gas introduction pipe, 22 ... Exhaust pipe, 23 ... 1st pore, 24 ... 2nd pore, 25 ... 3rd pore, 26 ... Vacuum pump, 27 ... Vacuum part, 28/29 DESCRIPTION OF SYMBOLS ... Differential exhaust part, 30 ... Roughing pump, 31 ... Converging lens, 32 ... Slit electrode, 33 ... Inner cylinder electrode, 34 ... Outer cylinder electrode, 35 ... Double circular deflector, 36 ... Ring electrode, 37 ... End cap electrode, 38 ... Gate electrode, 39 ... Tub electrode, 40 ... Quartz ring, 41 ... Lens, 42 ... Detector, 43 ... Amplifier, 44 ... Data processing device, 45 ... Ion drift part, 46 ... Corona discharge part, 47 ... Needle electrode, 48 ... Corona discharge region, 49 ... Counter electrode, 50 ... Opening, 51 ... Flow control unit, 52 ... Suction pump, 53 ... Main body, 54 ... Gas suction unit, 55 ... Housing, 56 ... Probe , 57 ... conveying device, 58 ... conveying device control device 59 ... signal line

Claims (3)

A first analysis step for obtaining a mass spectrum;
A first determination step of determining whether a first unique m / z ion is present;
Reading analysis conditions from a database according to the determination result of the first determination step;
A second analysis step of performing tandem mass spectrometry according to the analysis conditions. a first analysis step for obtaining an ⁿ th (MS ⁿ ) mass spectrum;
A first determination step of determining whether a first unique m / z ion is present;
Reading analysis conditions from a database according to the determination result of the first determination step;
And a second analysis step of performing ( ^{n + 1} ) ^-th order (MS ^{n + 1} ) mass analysis according to the analysis conditions.   In an analysis method using a mass spectrometer, the method includes dissociating ions having a wide range of m / z, performing mass analysis, and determining whether there is an ion having a specific m / z. Characteristic analysis method.

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