JP4108441B2 - Total aerosol analyzer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a total aerosol analyzer for measuring the concentration and components of airborne fine particles (aerosol).
[0002]
[Prior art]
Airborne particulate matter includes substances that affect the human body, such as environmental pollutants or pollen, and analysis of particulate matter in the atmosphere has become particularly important in recent years. Airborne particulates are particles ranging from several tens of microns to 1 / 100th of a micron, and are considered to contain a wide variety of substances. In particular, it is known that airborne particles having a size of about 10 to 1/10 microns are deposited in the nose, throat and respiratory organs.
[0003]
Epidemiologic studies to date have pointed out that airborne particulates (PM2.5) of 2.5 microns or less have a significant health impact on humans. According to a recent report from the United States, microparticles with a particle size of 2.5 microns are deposited in the lung, but it has been known that microparticles with a particle size of 1 micron are taken up by lung cells and have a significant effect on the human body. It was.
[0004]
If harmful chemical substances are attached around the airborne fine particles that enter the respiratory organs, there may be health effects mainly due to respiratory diseases. For example, diesel exhaust has been shown to contain large amounts of particulate matter, causing lung cancer, allergic rhinitis and bronchial asthma.
[0005]
Furthermore, inhalation of diesel exhaust has been shown to cause a decrease in the number of sperm in laboratory animals and to cause inflammation of the endocardium of the heart. From this, it is surmised that airborne particulates have an adverse effect on health.
[0006]
Therefore, analyzing the concentration and components of airborne particles below 2.5 microns is an important issue in atmospheric observation. As such an analysis apparatus, fine particles floating in the air atmosphere are charged and classified according to the electric mobility, and classified for each particle size, and the components and amounts for each particle size are determined by a high frequency inductively coupled plasma mass spectrometer and a Faraday. There exists what measures a cup ammeter (for example, refer to patent documents 1).
[0007]
As a device that is often used at present, there is a β-ray absorption method that measures the amount of β-ray absorption depending on the concentration of suspended particles by irradiating particles obtained by classifying the particle size with an inertial impactor and the like. It is used for suspended particulate measurement, and such products are also manufactured and sold (for example, β-ray suspended dust meter SPM-612 (for particles of 10 microns or less) from Kimoto Electronics Industry Co., Ltd.) -612D (for particles less than 2.5 microns).
[0008]
[Patent Document 1]
JP-A-10-288601 [0009]
[Problems to be solved by the invention]
In conventional suspended particle measurement, β rays emitted from a radiation source are used as an irradiation source. Since the conventional measurement object by the Air Pollution Control Law was particles of 10 microns or less, the amount of particles that can be measured even with a radiation source that can be used in an open system is collected under the current laws and regulations concerning radioactive materials. did it. However, when particles of 2.5 microns or less are targeted, it is known that the amount of collected source is small, so that the intensity of the source necessary for analyzing the particles is not sufficient and there is a problem in accuracy.
[0010]
Therefore, if you try to use a strong β-ray source, there will be a problem that at least in Japan, you will not be able to make a practical device because it conflicts with the laws and regulations. Furthermore, there is a problem that only the weight is measured and the component of the floating fine particles cannot be analyzed.
[0011]
Therefore, the present invention has been proposed in view of the above, and an electron beam source whose intensity and irradiation energy can be controlled instead of a radioactive substance (for example, promethium 147) has a small collection amount and a small particle size. An object of the present invention is to provide a total aerosol analyzer that enables fine particle measurement and component analysis using an X-ray source.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, a total aerosol analyzer according to claim 1 of the present invention is provided with an aerosol suction tube, an electron beam source, and an X-ray source sequentially from upstream to downstream of the take-up type aerosol collecting filter. An aerosol sample collected by the aerosol suction tube is formed on the take-up aerosol collection filter.
The electron beam source can be controlled in intensity and energy, and has an energy of 50 keV or less. The electron beam source is opposed to the take-up aerosol collection filter, and an electron beam detector is disposed opposite to the electron beam source for mass measurement. The mass measuring device is composed of a weight x (μg / cm ^{2) of the} aerosol sample moved immediately below the electron beam source. ) With the electron beam detector disposed so that the intensity I ₀ of the incident electron beam and the intensity I of the outgoing electron beam transmitted through the aerosol sample are opposed to the opposite side of the take-up type aerosol collecting filter 1. measured and is intended to seek more formula _{I = I 0 × exp (-μx} ), X -ray detector as in the X-ray source expects to aerosol samples on the same side as the winding-roll aerosol collection filter The X-ray detector is generated when gravimetric analysis is completed and the aerosol sample moved under the X-ray source is irradiated with excitation X-rays generated by the X-ray source. A total aerosol analyzer for analyzing the components of the aerosol sample using the characteristic X-rays using the fluorescent X-ray elemental analysis method was constructed.
[0013]
Thus, it is possible to configure without using illumination sources β rays emitted aerosol analyzer from the radiation source (radioisotope), can expand the use range because there is no restriction on the use of radioisotope, the analyzer Miniaturization and energy saving can be achieved.
[0014]
A total aerosol analyzer according to a second aspect of the present invention is the total aerosol analyzer according to the first aspect, wherein the electron beam source includes a diamond electron emitter for emitting electrons by a field emission method, and an electron beam. The X-ray source is composed of a transmissive diamond thin film, and the X-ray source includes an electron beam generating mechanism including a diamond electron emitter that emits electrons by a field emission method, and a tungsten metal for generating X-rays by the emitted electron beam. It consists of a target.
[0015]
Thus, the use of the electron beam source as the irradiation source, can use the following electron beam 50 keV, the sensitivity is increased with respect to the aerosol of light elements centered, 1. Min 0 micron fine aerosol Analysis is possible. Further, the inside of the electron beam source can be kept in a vacuum by the diamond thin film. Furthermore, since an X-ray source is used as an irradiation source for component analysis, the components of fine particles can be accurately measured based on the X-ray analysis method.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of a total aerosol analyzer of the present invention. In the figure, 1 is a take-up type aerosol collecting filter, 2 is an aerosol suction tube, 3 is an electron beam source, 4 is a diamond electron emitter, 5 is an electron beam transmissive diamond thin film, 6 is an electron beam detector, and 7 is an electron beam detector. An X-ray source, 8 is a diamond electron emitter, 9 is an X-ray detector, and 10 is an aerosol sample.
[0021]
In the total aerosol analyzer of the present invention, an aerosol suction tube 2, an electron beam source 3, and an X-ray source 7 are sequentially arranged from the upstream side to the downstream side of the take-up type aerosol collecting filter 1. An electron beam detector 6 is disposed opposite to the electron beam source 3 on the opposite side of the take-up type aerosol collecting filter 1 to constitute a mass measuring device. The X-ray source 7 is provided with an X-ray detector 9 on the same side as the take-up aerosol collecting filter 1 to constitute a component analyzer.
[0022]
The electron beam source 3 includes a diamond electron emitter 4 for emitting electrons by a field emission method, and a high-quality electron beam transmission diamond thin film 5. The diamond thin film 5 also serves to keep the inside of the electron beam source 3 in a vacuum.
[0023]
The X-ray source 7 has an electron beam generation mechanism similar to that of the electron beam source 3, and has a diamond electron emitter 8 that emits electrons by a field emission method. In order to generate X-rays by the emitted electron beam, a metal target such as tungsten is provided.
[0024]
The total aerosol analyzer of the present invention may be configured by arranging each device efficiently, or these individual devices may be integrated into a single device for miniaturization and energy saving. Can be planned.
[0025]
The embodiment of the present invention is configured to continuously collect aerosol equipped with a wind-up type aerosol collecting filter and an aerosol suction tube, and collects aerosol in the atmosphere at predetermined time intervals.
[0026]
Aerosol in the atmosphere adheres to the take-up type aerosol collection filter 1 and is transferred, and is collected by the aerosol suction tube 2 to form an aerosol sample 10. The aerosol sample 10 moves immediately below the electron beam source 3 and is exposed to the electron beam from the electron beam source 3. For the electron beam, an intensity of 50 keV or less is sufficient, and the dose of the electron beam is optimized.
[0027]
The intensity I ₀ of the incident electron beam and the intensity I of the emitted electron beam that has passed through the aerosol sample 10 are detected by the electron beam detector 6 that is arranged opposite to the opposite side of the take-up type aerosol collecting filter 1. The weight x (μg / cm ² ) of the aerosol sample 10 is obtained by the following equation (1) by the β-ray absorption method.
[0028]
[Expression 1]
I = I ₀ × exp (−μx) (1)
[0029]
In the electron beam source 3, electrons are emitted from the diamond electron emitter 4 by a field emission method. The electrons accelerated by an appropriate voltage are taken out into the atmosphere through the high-quality electron beam transmission diamond thin film 5. Here, the energy of the electrons is adjusted so as to obtain the best sensitivity according to the amount and particle size of the collected aerosol sample 10.
[0030]
The aerosol sample 10 after the gravimetric analysis is moved below the X-ray source 7. Excitation X-rays generated by the X-ray source 7 are applied to the aerosol sample 10, and the characteristic X-rays generated at that time are arranged so as to look at the aerosol sample 10 on the same side as the take-up type aerosol collecting filter 1. The component analysis of the aerosol sample 10 is performed by the X-ray detector 9 using the X-ray fluorescence elemental analysis method. The aerosol sample 10 that has been analyzed is discarded by the transfer of the take-up type aerosol collecting filter 1. And the same measurement process is repeated continuously for every predetermined time.
[0031]
As described above, the total aerosol analyzer of the present invention can realize the aerosol analyzer without using the β-ray irradiation source (radioisotope) emitted from the radiation source, so there is no restriction on the use of the radioisotope. So the range of use is expanded. In addition, since an electron beam of 50 keV or less can be used, sensitivity to light element-centered aerosol is increased, and analysis of 1.0-micron minute aerosol becomes possible.
[0032]
【The invention's effect】
As described above, the total aerosol analyzer of the present invention can be made compact and energy-saving by integrating individual devices into a single device. In addition, by using an electron beam source that can control the intensity and irradiation energy without using an irradiation source (radioisotope) emitted from a radiation source, it is possible to measure fine particles with small collection amount and small particle size. As a result, the sensitivity to aerosols centered on light elements is increased, and analysis of micro aerosols of 1.0 microns becomes possible.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a total aerosol analyzer of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rewind-type aerosol collection filter 2 Aerosol suction tube 3 Electron beam source 4, 8 Diamond electron emitter 5 Electron beam transmission type diamond thin film 6 Electron beam detector 7 X-ray source 9 X-ray detector 10 Aerosol sample

Claims (2)

An aerosol suction tube, an electron beam source, and an X-ray source are sequentially arranged from the upstream side to the downstream side of the wind-up type aerosol collection filter, and the wind-up type aerosol collection filter includes the aerosol suction tube. Forming an aerosol sample collected by
The electron beam source has controllable intensity and energy, and energy of 50 keV or less,
The electron beam source has an electron beam detector oppositely disposed on the opposite side of the take-up type aerosol collecting filter to constitute a mass measuring device, and the mass measuring device is moved directly below the electron beam source. Sample weight x (μg / cm ² ) With the electron beam detector disposed so that the intensity I ₀ of the incident electron beam and the intensity I of the outgoing electron beam transmitted through the aerosol sample are opposed to the opposite side of the take-up type aerosol collecting filter 1. measured and is intended to seek more formula _{I = I 0 × exp (-μx} ),
An X-ray detector is arranged in the X-ray source so as to look at the aerosol sample on the same side as the take-up type aerosol collecting filter, and a component analyzer is configured. The X-ray detector has been subjected to gravimetric analysis. The aerosol sample moved under the X-ray source is subjected to component analysis of the aerosol sample using the X-ray fluorescence elemental analysis of the characteristic X-ray generated when the excited X-ray generated by the X-ray source is irradiated. Total aerosol analyzer characterized by being a thing.   The electron beam source includes a diamond electron emitter for emitting electrons by a field emission method and an electron beam transmission type diamond thin film, and the X-ray source includes a diamond electron emitter for emitting electrons by a field emission method. The total aerosol analyzer according to claim 1, comprising: an electron beam generating mechanism, and a tungsten metal target for generating X-rays by the emitted electron beam.

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