Chemical substance detection apparatus and chemical substance detection method Number:7,064,323 from the United States Patent and Trademark Office (PTO) owispatent A vacuum ultraviolet lamp ionizes a chemical substance contained in exhaust gas Gs. The chemical substance ionized is trapped in an ion trapping apparatus in which a radio frequency electric field is formed. Energy is applied to an ion group in the ion trapping apparatus with a SWIFT waveform comprising a frequency component excluding a frequency corresponding to an orbital resonance frequency of ions of the chemical substance to remove an impurity. Energy is then applied to the ion group with a TICKLE waveform having a frequency component corresponding to the orbital resonance frequency of the ions of the chemical substance to fragmentate the ions of the chemical substance. A mass of the fragment is then measured with a mass spectrometer to identify the chemical substance.<H detection, substance, Chemical, substa, 7064323.html, Patent, pto, 7064323

Title: Chemical substance detection apparatus and chemical substance detection method

Abstract: A vacuum ultraviolet lamp ionizes a chemical substance contained in exhaust gas Gs. The chemical substance ionized is trapped in an ion trapping apparatus in which a radio frequency electric field is formed. Energy is applied to an ion group in the ion trapping apparatus with a SWIFT waveform comprising a frequency component excluding a frequency corresponding to an orbital resonance frequency of ions of the chemical substance to remove an impurity. Energy is then applied to the ion group with a TICKLE waveform having a frequency component corresponding to the orbital resonance frequency of the ions of the chemical substance to fragmentate the ions of the chemical substance. A mass of the fragment is then measured with a mass spectrometer to identify the chemical substance.

Patent Number: 7,064,323 Issued on 06/20/2006 to Yamakoshi, et al.

Inventors: Yamakoshi; Hideo (Kanagawa, JP); Futami; Hiroshi (Kanagawa, JP); Danno; Minoru (Kanagawa, JP); Tsuruga; Shigenori (Kanagawa, JP); Kuribayashi; Shizuma (Kanagawa, JP)
Assignee: Mitsubishi Heavy Industries, Ltd. (Tokyo, JP)

Appl. No.: 495044

Filed: June 27, 2003

PCT Filed: June 27, 2003

PCT NO: PCT/JP03/08237

371 Date: May 11, 2004

PCT PUB.NO.: WO20/05/001465

PCT PUB. Date: January 06, 2005

Current U.S. Class: 250/293 ; 250/281; 250/282; 250/283; 250/290; 250/291; 250/292; 435/287.2

Current International Class: H01J 49/00 (20060101); B01D 59/44 (20060101); C12M 1/34 (20060101)

Field of Search: 250/281-283,290-292 435/287.2

References Cited [Referenced By]

U.S. Patent Documents


4818869	April 1989	Weber-Grabau
5324939	June 1994	Louris et al.
5396064	March 1995	Wells
5517025	May 1996	Wells et al.
5521380	May 1996	Wells et al.
5528031	June 1996	Franzen
5808299	September 1998	Syage
5843311	December 1998	Richter et al.
5864136	January 1999	Kelley et al.
6649911	November 2003	Kawato
6828549	December 2004	Schweikhard et al.
6847037	January 2005	Umemura
2003/0155505	August 2003	Russ et al.
2005/0009172	January 2005	Yamakoshi et al.
2005/0235678	October 2005	Lee et al.

Foreign Patent Documents


1 291 651	Mar., 2003	EP
1-97350	Apr., 1989	JP
7-14540	Jan., 1995	JP
3032298	Feb., 2000	JP
2001-235406	Aug., 2001	JP
2002-181791	Jun., 2002	JP
2003-203601	Jul., 2003	JP
WO 01/096852	Dec., 2001	WO

Other References

S Kuribayashi et al., "Real-Time Detection System for Trace-Level Chlorinated Organic Compounds", Mitsubishi Heavy Industries Technical Review, vol. 38, No. 5, Sep. 30, 2001, pp. 262-265 and 286 (English translation, pp. 1-10). cited by other .
X. Jin et al., "On-Line Capillary Electrophoresis/Microelectrospray Ionization-Tandem Mass Spectrometry Using an Ion Trap Storage Time-of-Flight Mass Spectrometer with SWIFT Technology", Analytical Chemistry, vol. 71, No. 16, Aug. 15, 1999, pp. 3591-3597. cited by other .
U. Schuhle et al., "Sensitive Mass Spectrometry of Molecular Adsorbates by Stimulated Desorption and Single-Photon Ionization", J. Am. Chem. Soc., vol. 110, 1988, pp. 2323-2324. cited by other .
L. He et al., "Development of Capillary High-performance Liquid Chromatography Tandem Mass Spectrometry System Using SWIFT Technology in an Ion Trap/Reflectron Time-of-flight Mass Spectrometer", Rapid Communications in Mass Spectrometry, vol. 11, 1997, pp. 1739-1748. cited by other .
Y. Hori et al., "Analysis of Chlorophenol Monitored by an On-line Monitoring System for Dioxin Precursor in Flue Gas", Analysis II-Poster, Organohalogen Compounds, vol. 50, 2001, pp. 217-220. cited by other .
M. Yamada et al., "An Online System for Monitoring Dioxin Precursor in Flue Gas", Analysis-Poster, Organohalogen Compounds, vol. 45, 2000, pp. 149-151. cited by other.

Primary Examiner: Lee; John R.
Assistant Examiner: Souw; Bernard E.
Attorney, Agent or Firm: Foley & Lardner LLP

Claims

The invention claimed is:

1. A chemical substance detection apparatus, comprising: an ion trapping unit that traps, using any one of an electric field and a magnetic field, an ion group comprising ions of a chemical substance formed by ionization; an arbitrary waveform generation unit that generates a SWIFT waveform having a first voltage amplitude in a first frequency band corresponding to an orbital resonance frequency of a first impurity present in a concentration, a second voltage amplitude in a second frequency band corresponding to an orbital resonance frequency of a second impurity present in the concentration, and zero voltage amplitude in a third frequency band corresponding to an orbital resonance frequency of the chemical substance, wherein signal intensities corresponding to the first impurity and the second impurity are a predetermined signal intensity or larger, and wherein the first voltage amplitude is larger than the second voltage amplitude; and a mass analyzer that applies the SWIFT waveform generated in the arbitrary waveform generation unit to the ion group trapped by the ion trapping unit to remove the impurities, and then measures a mass of the chemical substance or a fragment thereof.

2. The chemical substance detection apparatus according to claim 1, further comprising an ionization unit that applies to the chemical substance energy higher than an ionization potential of the chemical substance and lower than a sum of the ionization potential and dissociation energy of ions of the chemical substance to ionize the chemical substance.

3. The chemical substance detection apparatus according to claim 2, wherein the ionization unit applies to the chemical substance energy higher than the ionization potential and equal to or smaller than a value of a sum of the ionization potential and 4 electron volts.

4. A chemical substance detection apparatus, comprising: an ion trapping unit that traps, using any one of an electric field and a magnetic field, an ion group comprising ions of a chemical substance formed by ionization; an arbitrary waveform generation unit that generates a SWIFT waveform in which a voltage amplitude is reduced as a frequency is increased; and a mass analyzer that applies the SWIFT waveform to the ion group trapped by the ion trapping unit to remove the impurity, and then measures a mass of the chemical substance or a fragment thereof.

5. The chemical substance detection apparatus according to claim 4, further comprising an ionization unit that applies to the chemical substance energy higher than an ionization potential of the chemical substance and lower than a sum of the ionization potential and dissociation energy of ions of the chemical substance to ionize the chemical substance.

6. The chemical substance detection apparatus according to claim 5, wherein the ionization unit applies to the chemical substance energy higher than the ionization potential and equal to or smaller than a value of a sum of the ionization potential and 4 electron volts.

7. A chemical substance detection method, comprising: an ion trapping step of trapping, using any one of an electric field and a magnetic field, an ion group comprising ions of a chemical substance formed by ionization; an arbitrary waveform generation step of generating a SWIFT waveform having a first voltage amplitude in a first frequency band corresponding to an orbital resonance frequency of a first impurity present in a concentration, a second voltage amplitude in a second frequency band corresponding to an orbital resonance frequency of a second impurity present in the concentration, and zero voltage amplitude in a third frequency band corresponding to an orbital resonance frequency of the chemical substance, wherein signal intensities corresponding to the first impurity and the second impurity are a predetermined signal intensity or larger, and wherein the first voltage amplitude is larger than the second voltage amplitude; and a mass analyzing step of applying the SWIFT waveform generated in the arbitrary waveform generation step to the ion group trapped in the ion trapping step to remove the impurities, and then measuring a mass of the chemical substance or a fragment thereof.

8. The chemical substance detection method according to claim 7, wherein the mass analyzing step includes measuring at least two members among isotopes of fragments formed from the chemical substance.

9. The chemical substance detection method according to claim 7, further comprising an ionization step of applying, before executing the ionization trap step, to the chemical substance energy higher than an ionization potential of the chemical substance and lower than a sum of the ionization potential and dissociation energy of ions of the chemical substance to ionize the chemical substance.

10. The chemical substance detection method according to claim 9, wherein the ionization step includes applying to the chemical substance energy higher than the ionization potential and equal to or smaller than a value of a sum of the ionization potential and 4 electron volts.

11. A chemical substance detection method, comprising: an ion trapping step of trapping, using any one of an electric field and a magnetic field, an ion group comprising ions of a chemical substance formed by ionization; an impurity removing step of applying a SWIFT waveform in which a voltage amplitude is reduced as a frequency is increased to remove an impurity from the chemical substance; and a mass analyzing step of measuring a mass of the chemical substance or a fragment thereof.

12. The chemical substance detection method according to claim 11, wherein the mass analyzing step includes measuring at least two members among isotopes of fragments formed from the chemical substance.

13. The chemical substance detection method according to claim 11, further comprising an ionization step of applying, before executing the ionization trap step, to the chemical substance energy higher than an ionization potential of the chemical substance and lower than a sum of the ionization potential and dissociation energy of ions of the chemical substance to ionize the chemical substance.

14. The chemical substance detection method according to claim 13, wherein the ionization step includes applying to the chemical substance energy higher than the ionization potential and equal to or smaller than a value of a sum of the ionization potential and 4 electron volts.

15. A chemical substance detection method, comprising: an ion tapping step of trapping, using any one of an electric field and a magnetic field, an ion group comprising ions of a plurality of chemical substances having different masses formed by ionization; a step of applying to the ion group a SWIFT waveform which gives no voltage amplitude in a plurality of frequency bands corresponding to mass numbers of a plurality of chemical substances to remove an impurity while leaving the chemical substances; a fragmentation step of fragmenting the chemical substance in an order of from a chemical substance having a smaller mass number to a chemical substance having a larger mass number; and a mass analyzing step of measuring masses of the chemical substances or the fragments thereof.

16. The chemical substance detection method according to claim 15, wherein the mass analyzing step includes measuring at least two members among isotopes of fragments formed from the chemical substance.

17. The chemical substance detection method according to claim 15, further comprising an ionization step of applying, before executing the ionization trap step, to the chemical substance energy higher than an ionization potential of the chemical substance and lower than a sum of the ionization potential and dissociation energy of ions of the chemical substance to ionize the chemical substance.

18. The chemical substance detection method according to claim 17, wherein the ionization step includes applying to the chemical substance energy higher than the ionization potential and equal to or smaller than a value of a sum of the ionization potential and 4 electron volts.

19. A chemical substance detection method, comprising: an ion trapping step of trapping, using any one of an electric field and a magnetic field, an ion group comprising ions of a plurality of chemical substances having different masses formed by ionization; a step of applying to the ion group a SWIFT waveform which gives no voltage amplitude in a plurality of frequency bands corresponding to mass numbers of a plurality of chemical substances to remove an impurity while leaving the chemical substances; and a fragmentation step of applying energy to at least two isotopes of the chemical substances by means of a TICKLE waveform comprising frequency components corresponding to the two isotopes to fragmentate the two isotopes; and a mass analyzing step of measuring masses of the chemical substances or the fragments thereof.

20. The chemical substance detection method according to claim 19, wherein the mass analyzing step includes measuring at least two members among isotopes of fragments formed from the chemical substance.

21. The chemical substance detection method according to claim 19, further comprising an ionization step of applying, before executing the ionization trap step, to the chemical substance energy higher than an ionization potential of the chemical substance and lower than a sum of the ionization potential and dissociation energy of ions of the chemical substance to ionize the chemical substance.

22. The chemical substance detection method according to claim 21, wherein the ionization step includes applying to the chemical substance energy higher than the ionization potential and equal to or smaller than a value of a sum of the ionization potential and 4 electron volts.

Description

TECHNICAL FIELD

The present invention relates to a chemical substance detection apparatus and a method for measuring a chemical substance concentration, and more particularly to a chemical substance detection apparatus and a chemical substance detection method, which are used for detecting, with high accuracy, a dioxin or a precursor thereof contained in a very slight amount in the exhaust gas from, for example, a refuse incineration system.

BACKGROUND ART

Recently, for reducing dioxins contained in the exhaust gas from a refuse incineration system, attempts are being made to measure in real time dioxins or precursors thereof contained in the exhaust gas and use the measurement values for controlling combustion of the incineration furnace. The dioxins may be measured with high-resolution GC/MS (gas chromatography/mass spectrometer). However, this method requires cumbersome pretreatment and, currently, a time of from sampling to obtaining a result needs several weeks so that it is not practical to use this method where real-timeness is required. An on-line monitor is known in which dioxins or precursors thereof contained in exhaust gas are ionized by an atmospheric pressure chemical ionization method and the resultant ions are measured by means of a three-dimensional tetrode mass spectrometer. The on-line monitor has been described in detail in Abstracts of the 11th Conference 2000 of Japan Society of Waste Management Experts, and see the literature if necessary.

However, the atmospheric pressure chemical ionization method has the following problems. First, the sensitivity for measurement of molecules which are hardly changed to negative ions is low due to its measurement principle, and therefore the method is difficult to apply to control with high precision. The ionization probability of a chemical substance to be measured is largely affected by the gas composition of an atmosphere. Thus, for determining a concentration of the chemical substance from the measured electric signal intensity by making calculation, it is necessary to use a chemical substance containing an expensive C isotope as an internal standard sample, increasing the cost for the measurement.

In the atmospheric pressure chemical ionization method, generally, a phenol is detected wherein there is a correlation between a phenol and a dioxin with respect to the concentration and a phenol has relatively high sensitivity of measurement. However, the phenol is likely to be deposited on a pipe and therefore the memory effect is remarkable, and, for achieving a measurement with high sensitivity, piping is required to be improved with some contrivances. In addition, even in cleaned exhaust gas, a phenol is disadvantageously detected due to the memory effect, thereby lowering the accuracy of the measurement. Further, when a substance which is more easily ionized than the precursor to be measured is present in the exhaust gas, such a substance is first ionized, thus making it difficult to accurately measure the substance to be measured.

A certain precursor (e.g., trichlorophenol), which is an optimal index substance of the dioxin concentration for one furnace, is not always an optimal index substance for another furnace since there may be a difference between the one furnace and another with respect to the type of furnace or the conditions for combustion, and thus, the method which can measure a single precursor has only poor general-purpose properties. In other words, a method having improved general-purpose properties advantageously can detect various types of chemical substances simultaneously if possible.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to solve at least the problems in the conventional technology.

A chemical substance detection apparatus according to an aspect of the present invention includes an ionization unit that applies to a chemical substance energy higher than an ionization potential of the chemical substance and lower than a sum of the ionization potential and dissociation energy of ions of the chemical substance to ionize the chemical substance; an ion trapping unit that traps, using any one of an electric field and a magnetic field, an ion group comprising the ions of the chemical substance formed by ionization by the ionization unit; an impurity removing unit that applies energy to the ion group by means of a SWIFT waveform comprising a frequency component excluding a frequency corresponding to an orbital resonance frequency of the ions of the chemical substance to remove an impurity from the chemical substance; and a mass analyzer that measures a mass of the chemical substance.

In the chemical substance detection apparatus according to the above-mentioned aspect, in ionization of a detection object chemical substance, energy higher than an ionization potential of the detection object chemical substance and lower than a sum of the ionization potential and dissociation energy of ions of the detection object chemical substance is applied to the detection object chemical substance. Therefore, the chemical substance to be detected can be ionized without being broken, making it possible to improve the ionization efficiency.

Further, a SWIFT waveform is merely applied for removing an impurity and hence, the impurity can be quickly removed. In the ionization according to the present invention, the energy required for ionization is appropriately adjusted, and hence various molecules do not unnecessarily suffer dissociation or ionization. Therefore, only a very few fragments are generated and the amount of impurities to be removed in the step of removing an impurity is extremely small, so that the SWIFT voltage can be lowered to allow the chemical substance to be detected to be left to remain unbroken, making it possible to improve the detection sensitivity of the mass analyzer. In addition, there is no need to prepare an excessively high power source and the production cost for the apparatus can be suppressed. Further, in the chemical substance detection apparatus according to the present invention, generation of excessive fragment ions can be considerably suppressed, thus making it possible to suppress a lowering of the trapping efficiency caused by an excess amount of ions present in the ion trap. As the mass analyzer, it is especially preferred to use one of a time-of-flight measurement mode since the time for measurement can be shortened. In the ion trapping unit, a unit that traps ions in the unit using an electric field, a magnetic field, or another electromagnetic force can be used. An electric field, a magnetic field, and other unit may be used individually or a plurality of these may be used in combination appropriately. As such an ion trapping unit, an ion trap in which a radio frequency electric field is formed is known, and this is preferred because the handling is relatively easy (this applies to the following).

The term "detection object chemical substance" here means a precursor of a dioxin or a dioxin contained in the exhaust gas from, for example, an incineration furnace. In the chemical substance detection apparatus according to the present invention, a dioxin concentration of the exhaust gas can be presumed by detecting a precursor having a good correlation with a dioxin. Alternatively, a dioxin contained in the exhaust gas can be directly detected to determine the dioxin concentration. The latter can be used for detecting a presumed value by a precursor. Dioxins generally include dioxins, furans, and molecules called coplanar PCB. The precursors include benzenes, such as trichlorobenzene, dichlorobenzene, and monochlorobenzene, and phenols, such as trichlorophenol.

In addition, SWIFT represents "Stored Waveform Inverse Fourier Transform". See "Development of a Capillary High-Performance Liquid Chromatography Tandem Mass Spectrometry System Using SWIFT Technology in an Ion Trap/Reflectron Time-of-flight Mass Spectrometer", Rapid Communication in mass spectrometry, vol. 11 1739 1748 (1997), for details.

A chemical substance detection apparatus according to another aspect of the present invention includes an ionization unit that applies to a chemical substance energy higher than an ionization potential of the chemical substance and lower than a sum of the ionization potential and dissociation energy of ions of the chemical substance to ionize the chemical substance; an ion trapping unit that traps, using any one of an electric field and a magnetic field, an ion group comprising the ions of the chemical substance formed by ionization by the ionization unit; an impurity removing unit that applies energy to the ion group by means of a SWIFT waveform comprising a frequency component excluding a frequency corresponding to an orbital resonance frequency of the ions of the chemical substance to remove an impurity from the chemical substance; a fragmentation unit that applies energy to the ion group by means of a TICKLE waveform comprising a frequency component corresponding to the orbital resonance frequency of the ions of the chemical substance to fragmentate the ions of the chemical substance; and a mass analyzer that measures a mass of a fragment of the chemical substance.

In the chemical substance detection apparatus according to the above-mentioned aspect, fragmentation of the detection object chemical substance is performed by means of a fragmentation unit that applies a TICKLE waveform. Therefore, even when an impurity is present in a frequency band corresponding to the mass number of the detection object chemical substance, the effect of the impurity can be removed to achieve an accurate measurement. In addition, only a very few fragments are generated in the ionization and therefore, in the fragmentation of the detection object chemical substance, the desired detection object chemical substance can be efficiently subjected to fragmentation. Accordingly, almost all the fragments of the detection object chemical substance can be subjected to measurement of the mass analyzer, and therefore the detection sensitivity of the mass analyzer can be improved and the combustion can be controlled with higher precision. The TICKLE is an operation for subjecting a detection object chemical substance to fragmentation and separating the detection object chemical substance from an impurity having a mass number close to that of the detection object chemical substance. See "Development of a Capillary High-Performance Liquid Chromatography Tandem Mass Spectrometry System Using SWIFT Technology in an Ion Trap/Reflectron Time-of-flight Mass Spectrometer", Rapid Communication in mass spectrometry, vol. 11 1739 1748 (1997), for details.

In the chemical substance detection apparatus, the ionization unit applies to the chemical substance energy higher than the ionization potential and equal to or smaller than a value of a sum of the ionization potential and 4 electron volts. Furthermore, the ionization unit is a light generation unit that generates light having a wavelength of 50 to 200 nanometers. Moreover, the ionization unit is a vacuum ultraviolet lamp.

It is preferable that the energy applied to the detection object chemical substance by the ionization unit is higher than the ionization potential and equal to or smaller than a value of a sum of the ionization potential and 4 electron volts. When the detection object chemical substance is ionized by energy of light, the wavelength of the light is 50 to 200 nanometers. Such a light is preferred since it can be easily obtained using a vacuum ultraviolet lamp.

A chemical substance detection apparatus according to still another aspect of the present invention includes an ion trapping unit that traps, using any one of an electric field and a magnetic field, an ion group comprising ions of a chemical substance formed by ionization; an arbitrary waveform generation unit that generates a SWIFT waveform having a voltage amplitude in a frequency corresponding to an orbital resonance frequency of an impurity present in a concentration such that it exhibits a signal intensity higher than a predetermined signal intensity, wherein the voltage amplitude is larger than a voltage amplitude in a frequency band corresponding to an orbital resonance frequency of the impurity present in a concentration such that it exhibits a signal intensity lower than a predetermined signal intensity; and a mass analyzer that applies the SWIFT waveform generated in the arbitrary waveform generation unit to the ion group trapped by the ion trapping unit to remove the impurity, and then measures a mass of the chemical substance or a fragment thereof.

In the chemical substance detection apparatus according to the above-mentioned aspect, an impurity in an especially high concentration can be selectively removed by using a SWIFT waveform in which the voltage amplitude in a frequency corresponding to the mass number of an impurity present in a concentration higher than a specific signal intensity is increased and the voltage amplitude in a frequency corresponding to the mass number of an impurity present in a lower concentration is lowered. Thus, an impurity can be selectively removed and therefore only small energy is required for SWIFT. In addition, a power source apparatus can be reduced in size, and there is no need to use an excessively high power source and this is advantageous from an economical point of view. It is preferred that the impurity for which the voltage amplitude of a SWIFT waveform is increased is an impurity present in such a concentration that it exhibits at least a signal intensity substantially equivalent to the signal intensity of the detection object chemical substance. The impurity may be an impurity present in a further smaller mass number, but larger energy is required for SWIFT in such a case, and therefore it is preferred that the impurity is an impurity having a signal intensity 50 percent or more of the signal intensity of the detection object chemical substance.

A chemical substance detection apparatus according to still another aspect of the present invention includes an ion trapping unit that traps, using any one of an electric field and a magnetic field, an ion group comprising ions of a chemical substance formed by ionization; an arbitrary waveform generation unit that generates a SWIFT waveform in which a voltage amplitude is reduced as a frequency is increased; and a mass analyzer that applies the SWIFT waveform to the ion group trapped by the ion trapping unit to remove the impurity, and then measures a mass of the chemical substance or a fragment thereof.

In the chemical substance detection apparatus according to the above-mentioned aspect, the energy applied to an impurity having a larger mass number is higher than the energy applied to an impurity having a smaller mass number. Generally, the orbital resonance frequency in an ion trap is a function of a mass number, and, the larger the mass number, the smaller the frequency, or the smaller the frequency interval corresponding to the mass number interval 1. On the other hand, in the formation of a SWIFT waveform generally conducted in, for example, the literature, "Development of a Capillary High-Performance Liquid Chromatography Tandem Mass Spectrometry System Using SWIFT Technology in an Ion Trap/Reflectron Time-of-flight Mass Spectrometer". Rapid Communication in mass spectrometry, vol. 11 1739 1748 (1997), a SWIFT waveform is formed by subjecting a frequency spectrum having a fixed voltage amplitude to inverse Fourier transform to convert it to a time region. In this case, a waveform synthesized from waveforms having a fixed voltage amplitude at fixed frequency intervals is formed. Therefore, in this case, the larger the mass number, the smaller the number of the sinusoidal wave per mass number interval 1, and hence energy per mass number interval 1 is small. In other words, the energy applied to a molecule having a larger mass number becomes relatively small.

By contrast, in the chemical substance detection apparatus according to the above-mentioned aspect, the voltage amplitude of the sinusoidal wave is increased for making up for the reduced number of the sinusoidal wave, and therefore satisfactory energy can be also applied to ions having large mass numbers, so that even such impurities can be surely removed. In addition, energy in a required and satisfactory range can be applied to ions having small mass numbers and therefore the use efficiency of the energy can be improved. Further, an excessively high power source apparatus is not required, and hence the cost for the apparatus can be suppressed.

A chemical substance detection apparatus according to still another aspect of the present invention includes an ion trapping unit that traps, using any one of an electric field and a magnetic field, an ion group comprising ions of a chemical substance formed by ionization; an arbitrary waveform generation unit that generates a SWIFT waveform in which a voltage amplitude has a fixed distribution, irrespective of a mass number of a molecule to be removed by SWIFT; and a mass analyzer that applies the SWIFT waveform to the ion group trapped by the ion trapping unit to remove an impurity, and then measures a mass of the chemical substance or a fragment thereof.

The chemical substance detection apparatus according to the above-mentioned aspect is such that, when the frequency spectrum of a SWIFT waveform in which the voltage amplitude is increased as the frequency is smaller is converted so that the mass number is taken as an abscissa, the voltage amplitude per unit mass number is a substantially fixed value. Thus, substantially the same energy can be applied to molecules having any masses to be removed by SWIFT. Therefore, satisfactory energy can be also applied to ions having large mass numbers, and hence even such impurities can be surely removed. Further, an excessively high power source apparatus is not required, and hence the cost for the apparatus can be suppressed.

A chemical substance detection apparatus according to still another aspect of the present invention includes an ion trapping unit that traps, using any one of an electric field and a magnetic field, an ion group comprising ions of a chemical substance formed by ionization; an arbitrary waveform generation unit that generates a SWIFT waveform which gives no voltage amplitude in a plurality of frequency bands corresponding to mass numbers of a plurality of chemical substances, and which gives a voltage amplitude in a frequency band corresponding to a mass number of an impurity; a fragmentation unit that applies energy to the ion group by means of a TICKLE waveform having a plurality of frequency components corresponding to orbital resonance frequencies of the chemical substances to fragmentate the ions of the chemical substances; and a mass analyzer that applies the SWIFT waveform to the ion group trapped by the ion trapping unit to remove the impurity, and then measuring masses of the chemical substances or fragments thereof.

The amount of a dioxin or a precursor thereof contained in the exhaust gas from an incineration furnace is very slight, and an improvement of the detection accuracy therefor is very important when the conditions for combustion of the incineration furnace are controlled in real time. In the chemical substance detection apparatus according to the present invention, an impurity is removed using a SWIFT waveform which gives no voltage amplitude in the frequency bands corresponding to a plurality of detection object chemical substances. In addition, the detection object chemical substances are detected simultaneously by the mass analyzer. Thus, a plurality of detection object chemical substances are detected simultaneously and; therefore, a measurement with high accuracy can be achieved and the precision of the combustion control can be improved.

The chemical substance detection apparatus further includes an ionization unit that applies to the chemical substance energy higher than an ionization potential of the chemical substance and lower than a sum of the ionization potential and dissociation energy of ions of the chemical substance to ionize the chemical substance. Moreover, the ionization unit applies to the chemical substance energy higher than the ionization potential and equal to or smaller than a value of a sum of the ionization potential and 4 electron volts.

In the chemical substance detection apparatus according to the above-mentioned aspect, energy higher than the ionization potential of the detection object chemical substance and lower than the dissociation energy is applied to the detection object chemical substance to ionize the detection object chemical substance. Therefore, unnecessary fragments are not generated, and the detection object chemical substance to be left is allowed to remain unbroken, making it possible to improve the detection sensitivity of the mass analyzer. By virtue of this effect as well as the above-mentioned action and effect obtained by the chemical substance detection apparatus, the detection sensitivity of the mass analyzer is further improved, enabling a measurement with high accuracy. In addition, the combustion of an incineration furnace can be controlled with higher precision. Further, the SWIFT voltage can be lowered, and therefore there is no need to prepare an excessively high power source and the production cost for the apparatus can be suppressed.

A chemical substance detection method according to still another aspect of the present invention includes an ionization step of applying to a chemical substance energy higher than an ionization potential of the chemical substance and lower than a sum of the ionization potential and dissociation energy of ions of the chemical substance to ionize the chemical substance; an ion trapping step of trapping, using any one of an electric field and a magnetic field, an ion group comprising the ions of the chemical substance formed by ionization at the ionization step; an impurity removing step of applying energy to the ion group by means of a SWIFT waveform comprising a frequency component excluding a frequency corresponding to an orbital resonance frequency of the ions of the chemical substance to remove an impurity from the chemical substance; and a mass analyzing step of measuring a mass of the chemical substance.

In the chemical substance detection method according to the above-mentioned aspect, when an impurity is to be removed, energy higher than the ionization potential of a detection object chemical substance and lower than the dissociation energy is applied to the detection object chemical substance. Therefore, an impurity can be removed while allowing the detection object chemical substance to remain unbroken, and generation of unnecessary fragment ions can be considerably suppressed during the removal of an impurity. Accordingly, the detection object chemical substance to be left can be allowed to remain unbroken, making it possible to improve the detection sensitivity of the mass analyzer. Further, a SWIFT waveform is merely applied for removing an impurity and hence, the impurity can be quickly removed. In addition, in the ionization according to the present invention, only a very few fragments are generated and the amount of impurities to be removed in the step of removing an impurity is extremely small, so that the SWIFT voltage can be lowered, and hence there is no need to prepare an excessively high power source, and the production cost for the apparatus can be suppressed.

A chemical substance detection method according to still another aspect of the present invention includes an ionization step of applying to a chemical substance energy higher than an ionization potential of the chemical substance and lower than a sum of the ionization potential and dissociation energy of ions of the chemical substance to ionize the chemical substance; an ion trapping step of trapping, using any one of an electric field and a magnetic field, an ion group comprising the ions of the chemical substance formed by ionization at the ionization step; an impurity removing step of applying energy to the ion group by means of a SWIFT waveform comprising a frequency component excluding a frequency corresponding to an orbital resonance frequency of the ions of the chemical substance to remove an impurity from the chemical substance; a fragmentation step of applying energy to the ion group by means of a TICKLE waveform comprising a frequency component corresponding to the orbital resonance frequency of the ions of the chemical substance to fragmentate the ions of the chemical substance; and a mass analyzing step of measuring a mass of a fragment of the chemical substance.

In the chemical substance detection method according to the above-mentioned aspect, fragmentation of the detection object chemical substance is conducted by applying a TICKLE waveform to the detection object chemical substance. Therefore, even when an impurity is present in a frequency band corresponding to the mass number of the detection object chemical substance, the effect of the impurity can be removed to achieve an accurate measurement. In addition, only very few fragments are generated in the ionization and therefore, in the fragmentation of a detection object chemical substance, the desired detection object chemical substance can be efficiently subjected to fragmentation. Accordingly, almost all the fragments of the detection object chemical substance can be subjected to mass analysis, so that the detection sensitivity of analysis in the mass analyzer can be improved. By this detection method, in controlling the conditions for combustion of an incineration furnace, the combustion can be controlled with higher precision.

A chemical substance detection method according to still another aspect of the present invention includes an ion trapping step of trapping, using any one of an electric field and a magnetic field, an ion group comprising ions of a chemical substance formed by ionization; an impurity removing step of measuring a distribution of an impurity contained in the ion group and applying to the ion group a SWIFT waveform comprising a frequency component corresponding to an impurity present in a predetermined ratio or more to remove the impurity; and a mass analyzing step of measuring a mass of the chemical substance or a fragment thereof.

In the chemical substance detection method according to the above-mentioned aspect, an impurity present in a predetermined ratio or more is selectively removed. Therefore, the energy needed for removing the impurity in a required and satisfactory amount is small, as compared to the energy needed for removing all the impurities. Therefore, a power source apparatus can be reduced in size and this is advantageous from an economical point of view. It is preferred that the impurity in a predetermined ratio is an impurity present with at least a signal intensity substantially equivalent to the signal intensity of the detection object chemical substance. The impurity may be an impurity having a further smaller signal intensity, but larger energy is required for SWIFT in such a case, and therefore it is preferred that the impurity is an impurity having a signal intensity 50 percent or more of the signal intensity of the detection object chemical substance.

A chemical substance detection method according to still another aspect of the present invention includes an ion trapping step of trapping, using any one of an electric field and a magnetic field, an ion group comprising ions of a chemical substance formed by ionization; an arbitrary waveform generation step of generating a SWIFT waveform having a voltage amplitude in a frequency corresponding to an orbital resonance frequency of an impurity present in a concentration such that it exhibits a signal intensity higher than a predetermined signal intensity, wherein the voltage amplitude is larger than a voltage amplitude in a frequency band corresponding to an orbital resonance frequency of the impurity present in a concentration such that it exhibits a signal intensity lower than a predetermined signal intensity; and a mass analyzing step of applying the SWIFT waveform generated in the arbitrary waveform generation unit to the ion group trapped in the ion trapping step to remove the impurity, and then measuring a mass of the chemical substance or a fragment thereof.

In the chemical substance detection apparatus according to the above-mentioned aspect, the voltage amplitude of a SWIFT waveform in a frequency corresponding to the mass number of an impurity present in a high concentration such that it exhibits a signal intensity higher than a specific signal intensity is increased, and the voltage amplitude for an impurity in a low concentration is lowered. Therefore, an impurity in an especially high concentration can be selectively removed. An impurity can be selectively removed and hence only small energy is required for SWIFT. Thus, only small energy is required for SWIFT, and a power source apparatus can be reduced in size and there is no need to use an excessively high power source, and this is advantageous from an economical point of view. It is preferred that the impurity for which the voltage amplitude of a SWIFT waveform is increased is an impurity having at least a signal intensity substantially equivalent to the signal intensity of the detection object chemical substance. The impurity may be an impurity present in a further smaller mass number, but larger energy is required for SWIFT in such a case, and therefore it is preferred that the impurity is an impurity having a signal intensity 50 percent or more of the signal intensity of the detection object chemical substance.

A chemical substance detection method according to still another aspect of the present invention includes an ion trapping step of trapping, using any one of an electric field and a magnetic field, an ion group comprising ions of a chemical substance formed by ionization; an impurity removing step of applying a SWIFT waveform in which a voltage amplitude is reduced as a frequency is increased to remove an impurity from the chemical substance; and a mass analyzing step of measuring a mass of the chemical substance or a fragment thereof.

In the chemical substance detection method according to the present invention, the energy applied to an impurity having a larger mass number is higher than the energy applied to an impurity having a smaller mass number. Generally, the orbital resonance frequency in an ion trap is a function of a mass number, and, the larger the mass number, the smaller the frequency, or the smaller the frequency interval corresponding to the mass number interval 1. On the other hand, in the formation of a SWIFT waveform generally conducted in, for example, the literature "Development of a Capillary High-Performance Liquid Chromatography Tandem Mass Spectrometry System Using SWIFT Technology in an Ion Trap/Reflectron Time-of-flight Mass Spectrometer", Rapid Communication in mass spectrometry, vol. 11 1739 1748 (1997), a SWIFT waveform is formed by subjecting a frequency spectrum having a fixed voltage amplitude to inverse Fourier transform to convert it to a time region. In this case, a waveform synthesized from waveforms having a fixed voltage amplitude at fixed frequency intervals is formed. Therefore, in this case, the larger the mass number, the smaller the number of the sinusoidal wave per mass number interval 1, and hence energy per mass number interval 1 is small. In other words, the energy applied to a molecule having a larger mass number becomes relatively small.

By contrast, in the present invention, the voltage amplitude of the sinusoidal wave is increased for making up for the relatively small energy, and therefore satisfactory energy can be also applied to ions having large mass numbers, so that even such impurities can be surely removed. Further, an excessively high power source apparatus is not required, and hence the cost for the apparatus can be suppressed.

A chemical substance detection method according to still another aspect of the present invention includes an ion trapping step of trapping, using any one of an electric field and a magnetic field, an ion group comprising ions of a chemical substance formed by ionization; an arbitrary waveform generation step of generating a SWIFT waveform in which a voltage amplitude has a fixed distribution, irrespective of a mass number of a molecule to be removed by SWIFT; and a mass analyzing step of applying the SWIFT waveform to the ion group trapped at the ion trapping step to remove an impurity, and then measures a mass of the chemical substance or a fragment thereof.

This chemical substance detection method is such that, when the frequency spectrum of a SWIFT waveform in which the voltage amplitude is increased as the frequency is smaller is converted so that the mass number is taken as an abscissa, the voltage amplitude per mass number is a substantially fixed value. Thus, substantially the same energy can be applied to molecules having any masses to be removed by SWIFT. Therefore, satisfactory energy can be also applied to ions having large mass numbers, and hence even such impurities can be surely removed. Further, an excessively high power source apparatus is not required, and hence the cost for the apparatus can be suppressed.

A chemical substance detection method according to still another aspect of the present invention includes an ion trapping step of trapping, using any one of an electric field and a magnetic field, an ion group comprising ions of a chemical substance formed by ionization; a step of applying to the ion group a SWIFT waveform which gives no voltage amplitude in a plurality of frequency bands corresponding to mass numbers of a plurality of chemical substances to remove an impurity while leaving the chemical substances; and a mass analyzing step of measuring masses of the chemical substances or fragments thereof.

The amount of a dioxin or a precursor thereof contained the exhaust gas from an incineration furnace is very slight, and an improvement of the detection accuracy therefor is very important when the conditions for combustion of the incineration furnace are controlled in real time. In the chemical substance detection method according to the present invention, an impurity is removed using a SWIFT waveform which gives no voltage amplitude in the frequency bands corresponding to a plurality of detection object chemical substances. In addition, the detection object chemical substances are detected simultaneously by the mass analyzer. Thus, a plurality of detection object chemical substances are detected simultaneously and therefore, for example, even when the accuracy of detection of the individual detection object chemical substances is unsatisfactory, a plurality of substances are collectively examined from the correlation with dioxins or evaluated with respect to the combustion state to achieve a measurement with higher accuracy, and the precision of the combustion control can be improved.

A chemical substance detection method according to still another aspect of the present invention includes an ion trapping step of trapping, using any one of an electric field and a magnetic field, an ion group comprising ions of a plurality of chemical substances having different masses formed by ionization; a step of applying to the ion group a SWIFT waveform which gives no voltage amplitude in a plurality of frequency bands corresponding to mass numbers of a plurality of chemical substances to remove an impurity while leaving the chemical substances; and a fragmentation step of fragmenting the chemical substance in an order of from a chemical substance having a smaller mass number to a chemical substance having a larger mass number; a mass analyzing step of measuring masses of the chemical substances or the fragments thereof.

In the chemical substance detection method according to the present invention, a plurality of detection object chemical substances are successively subjected to fragmentation in the order of from a detection object chemical substance having a smaller mass number to those having larger one. Therefore, the fragmentation of the detection object chemical substance having a small mass number makes it possible to prevent the fragment of a substance having a mass number larger than that of the detection object chemical substance from being broken. Thus, all the detection object chemical substances can be detected, so that the sensitivity of mass analysis can be improved to achieve a measurement with higher accuracy.

A chemical substance detection method according to still another aspect of the present invention includes an ion trapping step of trapping, using any one of an electric field and a magnetic field, an ion group comprising ions of a plurality of chemical substances having different masses formed by ionization; a step of applying to the ion group a SWIFT waveform which gives no voltage amplitude in a plurality of frequency bands corresponding to mass numbers of a plurality of chemical substances to remove an impurity while leaving the chemical substances; and a fragmentation step of applying energy to at least two isotopes of the chemical substances by means of a TICKLE waveform comprising frequency components corresponding to the two isotopes to fragmentate the two isotopes; and a mass analyzing step of measuring masses of the chemical substances or the fragments thereof.

In the chemical substance detection method according to the present invention, the chemical substance detection method applies a TICKLE waveform comprising frequencies corresponding to at least two isotopes of the detection object chemical substance to subject at least two isotopes of the detection object chemical substance to fragmentation, making mass analysis. Thus, a plurality of isotopes are used in the mass analysis and therefore, even when a dioxin or a precursor thereof is present in an extremely slight amount in the exhaust gas, the accuracy of detection can be improved. In addition, when used in controlling the combustion of an incineration furnace, the precision of the control can be improved.

In the chemical substance detection method, the mass analyzing step includes measuring at least two members among isotopes of fragments formed from the chemical substance.

In the chemical substance detection method according to the present invention, at least two isotopes of fragments formed from the detection object chemical substance are subjected to mass analysis. Thus, a plurality of isotopes of fragments are used in the mass analysis and therefore, even when a dioxin or a precursor thereof is present in an extremely slight amount in the exhaust gas, the accuracy of detection can be improved. In addition, when used in controlling the combustion of an incineration furnace, the precision of the control can be improved.

The chemical substance detection method further includes an ionization step of applying, before executing the ionization trap step, to the chemical substance energy higher than an ionization potential of the chemical substance and lower than a sum of the ionization potential and dissociation energy of ions of the chemical substance to ionize the chemical substance.

In the chemical substance detection method, the ionization step includes applying to the chemical substance energy higher than the ionization potential and equal to or smaller than a value of a sum of the ionization potential and 4 electron volts.

In the methods for detecting a chemical substance according to the present invention, energy higher than an ionization potential of a detection object chemical substance and lower than a sum of the ionization potential and dissociation energy of ions of the detection object chemical substance is applied to the detection object chemical substance to ionize the detection object chemical substance. Therefore, unnecessary fragments are not generated, and the detection object chemical substance to be left is allowed to remain unbroken, making it possible to improve the detection sensitivity of mass analysis. By virtue of this effect as well as the above-mentioned action and effect obtained by the chemical substance detection method, the detection sensitivity of the mass analyzer is further improved, enabling a measurement with high accuracy. In addition, the combustion of an incineration furnace can be controlled with higher precision. Further, the SWIFT voltage can be lowered, and therefore there is no need to prepare an excessively high power source and the production cost for the apparatus can be suppressed.

The other objects, features, and advantages of the present invention are specifically set forth in or will become apparent from the following detailed descriptions of the invention when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory view illustrating a chemical substance detection apparatus according to the first embodiment of the invention;

FIG. 2 is a flowchart of a chemical substance detection method according to the first embodiment of the invention;

FIGS. 3A and 3B are explanatory diagrams of the ion signal intensity distributions versus the RF voltage when the trap frequency is fixed;

FIGS. 4A and 4B are explanatory diagrams of the ion signal intensity distributions versus the RF frequency when the RF voltage is fixed;

FIGS. 5A and 5B are diagrams explaining the relationship between a SWIFT frequency and an amplitude and the relationship between an ion signal and a mass number;

FIG. 6 is a diagram explaining a frequency spectrum of a SWIFT waveform according to the fifth embodiment of the invention;

FIGS. 7A and 7B are diagrams explaining a frequency spectrum of a conventional SWIFT waveform;

FIGS. 8A and 8B are diagrams explaining a frequency spectrum of a SWIFT waveform according to the sixth embodiment of the invention;

FIG. 9 is a diagram explaining a frequency spectrum of a SWIFT waveform according to the seventh embodiment of the invention;

FIGS. 10A and 10B are diagrams explaining a frequency spectrum of a TICKLE waveform according to the seventh embodiment of the invention; and

FIGS. 11A to 11D are diagrams explaining a frequency spectrum of a TICKLE waveform according to the ninth embodiment of the invention wherein the diagrams are individually obtained by converting the frequency spectrum so that the mass number is taken as an abscissa.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is described in detail below with reference to the accompanying drawings. The present invention, however, is not limited to exemplary embodiments. Further, elements in the exemplary embodiments include ones that are easily conceived by persons skilled in the art or ones subs