JP2010071981A - Asbestos identifying method using, as index, laser-induced fluorescence amount per unit area - Google Patents

Abstract

Provided is a method for easily discriminating asbestos from various substances in environmental samples that are generally considered difficult.
The first step of irradiating a specimen sample with laser light to generate substance-specific laser-induced fluorescence from the substance in the specimen sample, the laser-induced fluorescence generated within the microscope observation field from the irradiation laser wavelength The second step in which light is detected through an optical low-pass filter having light transmission characteristics in an arbitrary wavelength region in the long wavelength region, and the fluorescence from the fine particles is measured with a two-dimensional photodetector, the fluorescent image of the fine particles measured by the image measurement The third step to find the area where laser-induced fluorescence of fine particles is emitted and the integrated amount of fluorescence generated from the area, calculate the amount of fluorescence per unit irradiation area from the area where the fine particles generate fluorescence and the amount of fluorescence generated from the area And a laser-induced fluorescence per unit area comprising a fourth step of comparing the amount of fluorescence per unit area of asbestos determined in advance under the same measurement conditions. Asbestos identification method as an index the amount.
[Selection figure] None

Description

  The present invention relates to a method for identifying asbestos, and more particularly to a simple method for identifying asbestos floating in the atmosphere or asbestos contained in a building material.

  Conventional asbestos analysis methods include a dispersion staining method using a phase-contrast microscope that utilizes the difference in refractive index between asbestos particles and other substance particles, and a dispersion staining method using a phase-contrast microscope that can also check birefringence ( Patent Document 1), extinction angle method using a polarization microscope utilizing the birefringence of asbestos, X-ray diffraction analysis method using a basis standard absorption correction method utilizing the difference in crystal structure of the substance, extinction angle method using a polarization microscope Polarization determination method (PVS) using dark field epi-illumination (Non-patent Document 1), a method using a color reagent (Patent Documents 2 and 3), a method of adsorbing and dyeing a fluorescent dye (Patent Document) 4), a method using polarization characteristics of laser scattered light by asbestos fiber particles (Patent Document 5), an analysis method using laser Raman spectroscopy (Non-Patent Document 2), a method using biotechnology ( Patent Document 3), and the like. Among these, the X-ray diffraction analysis method using the dispersion staining method using a phase contrast microscope, the extinction angle method using a polarizing microscope, and the base standard absorption correction method is a qualitative analysis method for measuring the asbestos content in building materials and spray materials. This is a method defined in JIS A 1481 of 2006. In addition, as a method for measuring the concentration of scattered asbestos in the atmosphere regulated by the Air Pollution Control Law, the Asbestos Monitoring Manual (3rd edition, May 2007) by the Ministry of the Environment Microscopy is standard, and observation with an electron microscope or disperse staining is defined as a reference method as a means to supplement the results.

  However, these methods have a problem of measurement accuracy that, as a disadvantage, it takes a long period of time to obtain complicated preprocessing and analysis results, and in the case of microscopy, an artificial measurement error is large due to visual observation.

  The disperse dyeing method using a phase contrast microscope discriminates asbestos by observing a difference in color caused by a difference in refractive index of particles with a microscope. Since many mineral materials such as talc having a refractive index similar to that of asbestos are present in specimen samples consisting of many materials including building materials, identification by visual color difference can be performed even by a skilled expert. It will be a difficult task.

  The extinction angle method using a polarizing microscope requires skill in microscope operation and advanced expertise in optical properties of minerals regarding the determination method based on the extinction angle, and it is difficult for non-experts to identify asbestos. But it takes a long analysis time. In JIS A 1481, the combined use of a dispersion staining method using a phase-contrast microscope and an extinction angle method using a polarizing microscope is also shown as a reference, but the number of experts who can achieve both of these two methods is extremely small. For this reason, these methods are currently standard measurement techniques, but as a result, cumbersome labor and long analysis time are required to identify asbestos. In addition, high expertise and skill are indispensable for high-accuracy measurement, which causes a large variation in measurement accuracy (artificial measurement error) by analysts.

  Although the method described in Patent Document 1 and the polarization determination method (PVS), which are improved versions of the dispersion staining method using a phase contrast microscope and the extinction angle method using a polarization microscope, have seen improvements in measurement techniques, they still have similar problems. ing. In particular, in the polarization determination method (PVS), it is difficult to identify fine asbestos fiber particles, and the optical magnification does not reach that of a phase contrast microscope or a polarization microscope.

  Regarding asbestos discrimination by X-ray diffraction method, it has been pointed out that advanced knowledge and experience are required more than the disperse staining method and the extinction angle method (Non-patent Document 4).

  As described above, when performing high-precision measurement using a conventional method based on microscopic observation and X-ray diffraction, complicated labor and chemical treatment are required to prepare and measure a sample. Advanced expertise and skill are required. It is difficult to identify and measure asbestos on the spot in real time, and it takes a long time and much labor to obtain a result, and there is a problem that measurement accuracy depends on the skill of the measurer.

  On the other hand, the method using a color reagent, the method of adsorbing and dyeing fluorescent dyes, the method of adsorbing proteins, etc. are difficult to apply when the range of applicable building materials is unknown or other than chrysotile Therefore, there is a problem that the target range is limited when used.

  In addition, asbestos can be measured on the spot regardless of the skill of the measurer by the method using the polarization characteristic of the laser scattered light or the analysis method using Raman spectroscopy. However, since the former utilizes the polarization characteristics of the laser scattered light by the fibrous particles, there is a problem that discrimination from fiber particles other than asbestos is insufficient. Further, the latter has a problem that Raman scattered light is very weak and small, and there are many building materials, minerals, etc. that emit Raman scattered light in the same wavelength range, and therefore it is difficult to identify asbestos.

  When these conventional techniques are used alone, there are technical problems as described above, making it difficult to identify asbestos. When analyzing with high accuracy, advanced expertise, experience, and skill are required, and a plurality of the above conventional techniques must be used in combination. As a result, the method used in the prior art cannot identify and measure asbestos fiber particles quickly on the spot, and there is a problem that variation in measurement accuracy, long analysis time, and complicated labor are indispensable.

  Since it is difficult to accurately determine asbestos with current asbestos measurement technology, it is impossible to perform real-time measurement on the spot. Therefore, long days and complicated work are required for analysis of asbestos in building materials and environmental investigation of asbestos scattered at demolition work sites of aging buildings using asbestos-containing building materials.

  In addition, until now there have been three types of measurements, chrysotile, crocidolite and amosite. However, as a measure against asbestos health damage, according to the Ministry of Health, Labor and Welfare notification (No. 0206003, dated February 6, 2008), Analysis of three types of asbestos, the anthophyllite, tremolite, and actinolite of each of the olivine groups, was also required. However, with the asbestos measurement method using a phase contrast microscope using the dispersion staining method, which is currently the mainstream, dealing with such an increase in the number of measurements while maintaining a certain degree of measurement accuracy significantly increases the work time. Invite.

  On the other hand, although not applied to asbestos measurement, there is a time-resolved fluorescence spectroscopy (photometry) method as a technique for analyzing a relationship between a light emission mechanism of a substance and a chemical species by a fluorescence lifetime (Non-patent Document 5). In this method, the fluorescence spectrum is time-resolved to measure the change in spectrum and fluorescence lifetime, and quantitative analysis of a binary sample, identification of a substance, dynamic structure analysis of a molecule, and the like are performed (Patent Documents 6, 7 and 8). ). Moreover, as a typical example, a fluorescence lifetime microscope is used in the bio field for evaluation of intracellular microenvironment, detection of dyes, antibodies, amino acids, and the like (Patent Documents 9 and 10, Non-Patent Document 6). Unlike the fluorescence intensity, the fluorescence lifetime is not affected by the concentration of the substance. Therefore, in the bio and chemical analysis fields, it is mainly used for image detection or behavior analysis of fluorescent dyes, specific substances and the like. In order to detect the fluorescence lifetime, a lifetime measuring device and a lifetime analyzing device have been developed (Patent Documents 11 and 12). However, substance identification or identification method based on fluorescence lifetime has been used under very limited conditions such as in cells and chemical solutions, and various substances such as inorganic or organic substances such as asbestos are mixed. It is not generally used in the field of environmental analysis for analyzing samples. The reason for this is that a large number of substances having the same fluorescence lifetime are mixed, and enormous analysis time and labor are required to analyze these various and various fluorescence lifetimes. In addition, since these various samples have a large difference in fluorescence intensity, it is practically impossible to identify a substance having a trace amount and a weak fluorescence intensity.

JP 2005-338567 A JP 2000-88838 A JP-A-9-105743 JP-T-2004-519445 Japanese Patent Laid-Open No. 10-267828 Japanese Patent No. 3318019 JP 2004-294105 A JP 2003-522946 A JP 2002-286539 A JP-A-9-43146 JP-T-2006-519395 JP-A-8-334464

Shunichi Kamewada, Satoshi Wada, Keiji Ishii, Kazuaki Minami, Koichi Konari, Koichi Sakaiya, Hironobu Kamemoto, Michio Nishida, “Polarization determination device for asbestos in building materials (PVS) and field determination method using this”, industry and environment, vol . 35, no. 3,2006 Kazuo Tateishi, Junichi Furuya, Tadashi Kikuchi, Hideyuki Ishida, Jun Ishiya, “Analysis of asbestos in the environment by Raman microprobe”, BUNSEKI KAGAKU, vol. 30, pp. 774-779, 1981 Akio Kuroda, Kazutaka Nomura, Tomoki Nishimura, “Simple detection of asbestos using asbestos-binding protein”, Ohm, December, pp. 4-5, 2006 Kazuhiro Sasaki, Takao Nakakura, Hirokazu Fujimaki, “Problems of Asbestos Identification Using Dispersive Staining with a Phase-Contrast Microscope”, Bunkeki 4, pp. 177-184, 2007 Edited by Shigeo Minami and Yoichi Koshi, “Spectroscopy Handbook”, pp. 533-535, 1990 Bernard Valeur, “Molecular Fluorescence: Principal and Applications”, Weinheim: Wiley-VCH, 2002 Edited by Norio Hata, Shigeru Nakae, Keisuke Hirasawa: "Total Measurement and Control Technology of Airborne Particles for Air Purification", R & D Planning, 1987

  Therefore, the present invention provides a method for easily discriminating asbestos from various substances in environmental samples that are generally considered difficult by eliminating the disadvantages of conventional methods and using the amount of laser-induced fluorescence per unit area as an index. For the purpose.

  According to the present invention, by using the fluorescence amount per unit area of the substance-specific laser-induced fluorescence as an index for identifying asbestos, it is difficult to determine asbestos in the prior art, complicated processing or labor related to measurement, and Eliminate problems such as measurement accuracy.

  Specifically, the amount of fluorescence of laser-induced fluorescence of an arbitrary wavelength generated from a substance by irradiating the sample to be examined with laser light and the area of the substance emitting the laser-induced fluorescence are measured, and the amount of fluorescence per unit area Is detected and compared with the amount of fluorescence per unit area of reference asbestos prepared in advance to identify whether or not the specimen sample contains asbestos.

  In general, when a substance is irradiated with laser light, a substance-specific laser-induced fluorescence depending on the composition of the substance is generated from the surface of the substance. The generation wavelength range of the fluorescence is wider than the wavelength range of the laser light to be irradiated, and may range from several nanometers to several hundred nanometers. The generation characteristics of the fluorescence spectrum differ depending on the wavelength of the laser to be irradiated even with the same substance. When various substances are irradiated with laser light of the same wavelength, the amount of fluorescence generated, the wavelength showing the peak of the fluorescence spectrum, the shape of the fluorescence spectrum, and the fluorescence lifetime vary depending on the substance. Using the difference in the amount of fluorescence that varies depending on this substance, investigate the fluorescence generation characteristics of asbestos in an arbitrary wavelength region in advance to ascertain the amount of fluorescence per unit area, and use this as a standard for substances under the same conditions. Asbestos can be identified by comparing the amount of fluorescence per unit area.

  In general, detailed identification of a substance from fluorescence is considered difficult. However, in the present invention, laser-induced fluorescence in a specific wavelength region is detected, the area of the substance emitting laser-induced fluorescence in the specific wavelength region is obtained by microscopic observation, and the amount of laser-induced fluorescence per unit area is simplified. In addition, the present invention provides a method for identifying asbestos from various substances in an environmental sample with high accuracy by strictly detecting it.

  The present invention is obtained by performing laser irradiation in a sample mixed with asbestos, and detecting the accumulated fluorescence amount or peak value in a specific wavelength region of the laser-induced fluorescence generated therein and the area of the substance emitting the laser-induced fluorescence. This is a simple method that simply compares the amount of fluorescence per unit area. In addition, since it can be evaluated numerically as compared with the identification method used in the prior art, it is a simple and highly accurate identification method for asbestos. For this reason, the present invention is an effective means for solving an artificial error associated with visual asbestos determination, a complicated operation of a microscope, sample pretreatment, and the like, which are problems of the prior art.

  Next, the principle of asbestos identification using the amount of fluorescence per unit area as an index will be described.

  When a monochromatic laser beam is irradiated on a natural or artificially generated substance such as a chemical substance, organic substance, or inorganic substance, laser-induced fluorescence is generated from the substance surface. In general, this fluorescence is generated in a wide wavelength range longer than the irradiated laser wavelength. Under the same wavelength laser irradiation condition, it shows different generation characteristics for each substance, and the generated spectrum wavelength range, intensity, and fluorescence lifetime are different. Different. In FIG. 1, the spectrum conceptual diagram of the laser-induced fluorescence of different substances A, B, and C is shown. The laser-induced fluorescence spectrum basically differs in the generation wavelength range, spectrum shape, and fluorescence lifetime of the substance if the composition of the substance is different. The fluorescence amount of the fluorescence spectrum (accumulated fluorescence amount) is obtained by integrating the fluorescence intensity at each wavelength over the wavelength range where the spectrum is generated, and the amount is determined by the fluorescence spectrum line in FIG. It corresponds to the area of the enclosed region. Since the laser irradiation area is the same, the area, that is, the amount of the fluorescence spectrum per unit area differs depending on the substance. Therefore, by calculating the amount of fluorescence per unit area of the substance in the sample and comparing it with the previously determined amount of fluorescence per unit area of asbestos (reference asbestos fluorescence amount), whether the substance is asbestos or not. Can be identified. In addition, as shown in FIG. 1, when the substance A, B and C have specific peaks with significantly different fluorescence spectrum shapes, only the fluorescence intensity per unit area of this specific peak (wavelength λ1 shown in FIG. 1) is obtained. Substances can be identified only by comparison.

  Since asbestos can be identified by the numerical value of the amount of fluorescence per unit area, asbestos measurement can be performed more easily and faster than conventional techniques such as microscopic observation methods such as observation and identification by visual observation. In the present invention, the fluorescence amount per unit area of various types of asbestos is measured in advance, and the fluorescence amount per unit area of the measurement target substance is measured and compared as known data (reference asbestos fluorescence amount). . Therefore, not only is it easy to distinguish from substances other than asbestos, but even if the number of types of asbestos to be measured increases, it is also easy to identify asbestos by type. Increase in the number of specimen samples, increase in pretreatment, etc.).

  FIG. 6 shows a conceptual diagram of the asbestos identification device of the present invention. The asbestos identification device includes a pulsed laser light source (d), a low-pass filter or band-pass filter (b) having light transmission characteristics in an arbitrary wavelength region in the optical path of the objective lens, and the low-pass filter or band-pass filter (b). A high-speed gated high-sensitivity CCD camera (a) for observing the laser-induced fluorescence separated by), and the area of fine particles emitting laser-induced fluorescence from the image of the high-speed gated high-sensitivity CCD camera And a measurement control device (g) for calculating the fluorescence amount per unit irradiation area from the fluorescence amount generated from the area and obtaining the fluorescence amount per area.

Next, an asbestos identification method using the asbestos identification apparatus shown in FIG. 6 will be described. First, the specimen sample (f) is irradiated with a pulsed laser with a microscope system. A low-pass optical filter with transmission characteristics in the wavelength range longer than the wavelength of the laser that emits laser-induced fluorescence emitted from fine particles in the specimen sample or a bandpass with transmission characteristics in any narrow wavelength range in the generation wavelength range of laser-induced fluorescence (Interference) The sample is observed with a high sensitivity CCD camera (a) through an optical filter (wavelength λ _A ) (b). A fluorescence microscope image (lower right in the figure) through the optical filter (b) is obtained by the high sensitivity CCD camera (a). This image is taken into a personal computer or the like which is the measurement control device (g), image processing is performed, the area of the fluorescent fine particles is calculated, and a predetermined generated from the fine particles based on the CCD signal from the fine particle image. The integrated fluorescence amount in the wavelength region is derived. The amount of fluorescence per unit area is obtained from the area of the fine particles emitting fluorescence and the amount of accumulated fluorescence, and compared with the amount of accumulated fluorescence per unit area of asbestos under the same measurement conditions investigated in advance. The fine particles identified as asbestos by this process are counted as one asbestos fiber particle. All the asbestos particles in the image are counted by repeatedly performing an image identification process relating to asbestos identification for one fine particle in the image on all the fine particles appearing in the image.

FIG. 1 shows a conceptual view of the spectrum of laser-induced fluorescence of different substances A, B and C. FIG. 2 shows a time sequence of fluorescence spectrum measurement. (A) is an irradiation laser pulse, (b) is laser-induced fluorescence, and (c) is a gate exposure time of the photodetector of the spectrometer. FIG. 3 shows laser-induced fluorescence spectra of three types of asbestos (chrysotile, crocidolite, amosite, tremolite, anthophyllite). FIG. 4 shows laser-induced fluorescence spectra of glass wool, rock wool and rock fiber, which are fibrous materials. FIG. 5 shows laser-induced fluorescence spectra of talc, gypsum and cement, which are non-fibrous materials. FIG. 6 shows an embodiment of the asbestos identification device of the present invention. FIG. 7 shows the fluorescence of these particles in which laser-induced fluorescence generated from asbestos particles and glass wool particles by ultraviolet (wavelength 266 nm) laser irradiation in the microscope system which is one embodiment of the asbestos identification device of the present invention shown in FIG. An image is shown.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

[Example 1]
A sample (irradiation area to 0.8 cm ² ) was irradiated with an ultraviolet pulse laser (Nd: YAG laser quadruple wave, wavelength 266 nm, pulse time width to 4 ns) to generate laser-induced fluorescence. FIG. 2 shows a time sequence representing a temporal correlation between the pulse laser, the laser-induced fluorescence generated, and the gate time of the CCD camera. The laser-induced fluorescence attenuates as shown in FIG. 2 depending on the elapsed time generated from the material immediately after laser irradiation. The fluorescence was integrated 100 times with an exposure (gate) time of 200 ns with a multichannel spectrometer and averaged, and a fluorescence spectrum with a wavelength of 350 to 700 nm was measured. In order to remove the laser scattered light, a low-pass optical filter having a cutoff wavelength of 360 nm was used in the spectroscope. Note that the shape of the fluorescence spectrum changes depending on the transmission characteristics of the low-pass filter used, and the amount of fluorescence to be measured also changes.

  In FIG. 3, laser induction from a wavelength of about 350 nm to 700 nm is generated from the same laser irradiation area from a bulk sample in which fiber particles of five types of asbestos, which are typical asbestos, crocidolite, amosite, tremolite, and anthophyllite are consolidated. The fluorescence spectrum is shown respectively. These fluorescence spectra are obtained by measuring laser-induced fluorescence generated from the same laser irradiation area on the material surface under the same measurement conditions. The chrysotile fluorescence spectrum shows peak intensities of about 0.5 times that of anthophyllite, about 10 times that of crosidyl and amosite, and about 1.5 times that of tremolite, but the spectrum shape is very similar. It was found that there was a significant difference in the amount of fluorescence among these five types of asbestos, there was a difference that could be discriminated, and there was a clear difference in peak intensity. It can be seen that these asbestos can be identified even by the difference in intensity between the peak wavelengths of the asbestos.

  FIG. 4 shows fluorescence spectra of glass wool, rock wool, and glass wool, which are fibrous materials similar to asbestos that are easily misidentified as asbestos. The fluorescence spectrum of these fibrous substances showed a spectrum shape different from that of asbestos, and the peak position was found to be on the longer wavelength side from 50 nm to 100 nm. Moreover, also in the peak fluorescence intensity, it turned out that especially glass wool is about 30 times or more higher than chrysotile, and rock wool and rock fiber are about 5 to 7 times higher. Thus, it was observed that fibrous materials that are easily misidentified as asbestos, such as glass wool, rock wool, and rock fiber, emit significantly more fluorescence than asbestos.

FIG. 5 shows a laser-induced fluorescence spectrum measured under the same conditions as FIGS. 3 and 4 for talc, gypsum, and cement of a building material sample that is a non-fibrous substance and is often mixed into an inspection sample during asbestos inspection. Talc and gypsum have almost the same spectral shape. The fluorescence intensity at the peak value is about 10 times for talc (2.0 × 10 ⁶ ) and about gypsum (7.8 × 10 ⁶ ) compared to chrysotile (1.95 × 10 ⁵ ). It was 4 times higher. On the other hand, although the cement has a spectrum shape very similar to that of talc and gypsum, the strength was as low as 1/40 or less than that of talc at the peak.

  Table 1 shows a summary of the total fluorescence amount of wavelengths 350 to 700 nm of the fluorescence spectra of all the substances shown in FIGS. 3, 4 and 5 with reference to the value of chrysotile (1). These values are obtained by collecting the fluorescence amounts generated from the same laser irradiation area on the sample surface under the same measurement conditions, and correspond to the ratio of the fluorescence amount per unit area of the particles.

  As shown in Table 1, it can be seen that the ratio of the accumulated fluorescence amount varies greatly between substances. Asbestos is classified into the substances with the smallest fluorescence. Cement was about 1/5 of chrysotile, crocidolite was about 1/8, amosite was about 1/20, tremolite was about 2/3, and anthophyllite was about 1.8 times. Further, glass wool, which is a fibrous material that is easily misidentified as asbestos, was 25 times or more higher than chrysotile, and rock wool and rock fiber were about 6-8 times higher. It has been found that talc and gypsum, which are non-fibrous substances other than cement, generate an integrated fluorescence amount that is 9 times or 3 times that of chrysotile, respectively. Therefore, since there is a remarkable difference in such remarkable numerical values in the amount of fluorescence per unit area between asbestos and other substances, it is possible to identify asbestos with high accuracy by using these numerical values.

  In Table 1, the accumulated fluorescence amounts at wavelengths of 350 to 700 nm were compared. Asbestos can also be identified by comparing the fluorescence intensity per unit area of the peak values of each spectrum waveform shown in FIGS. 3, 4, and 5. That was mentioned above. However, in this case, a complicated analysis operation for acquiring a fluorescence spectrum waveform for each substance and detecting a peak value is indispensable. As a method for easily identifying asbestos from the fluorescence intensity without this trouble, a method for identifying with the fluorescence intensity in an arbitrary wavelength range by a bandpass filter having transmission characteristics in a narrow wavelength range is shown below. Table 2 shows the results of summarizing the fluorescence intensity of each substance around the wavelength of 522 nm on the basis of chrysotile as in Table 1. In this method, troublesome spectral analysis work is not required, and the fluorescence intensity in an arbitrary narrow wavelength region can be easily obtained with the same measurement condition with a single bandpass filter.

  From the fluorescence intensity at a wavelength of 522 nm per unit area, there is a significant difference between asbestos and other substances, and also between the types of asbestos, and it can be seen from these numerical values that asbestos can be identified. However, when discriminating by the fluorescence intensity in a narrow wavelength range, there is a substance that exhibits the same fluorescence intensity as asbestos depending on the wavelength range to be selected, so care must be taken in selecting the wavelength range for comparing the fluorescence intensity. As shown in Table 2, it is necessary to select a wavelength region in which the difference in fluorescence intensity between substances is significant.

  In this way, the accumulated amount of fluorescence in a long wavelength region and the amount of fluorescence per unit area in one arbitrary narrow wavelength region are greatly different between asbestos and other substances. In addition, asbestos can be easily and quickly identified by detecting the accumulated fluorescence amount or fluorescence intensity per unit area of the substance by microscopic observation and comparing it with that of asbestos. If image processing is performed on a fluorescence microscopic image obtained by fluorescence observation with a microscope using a personal computer or the like, asbestos can be automatically identified and counted without artificial visual measurement.

[Example 2]
The integrated fluorescence amount ratio shown in Table 1 is based on the fluorescence amount from a bulk sample measured by a spectroscopic test using a bulk sample obtained by solidifying fibrous or powdered asbestos and a building material sample. In order to confirm that the difference in the fluorescence amount ratio corresponding to the cumulative fluorescence amount ratio shown in Table 1 is actually obtained even with the particles observed with the microscope system illustrated in FIG. 6, a microscope observation test of the fluorescence amount from the particles was performed. .

  The observed samples are fibrous particles of chrysotile (asbestos) and glass wool (asbestos alternative building material sample). A sample in which the particles were sandwiched between two glass slides made of quartz glass for microscope observation was observed with a microscope. 7 irradiates pulse laser light having a wavelength of 266 nm as in FIG. 3, and uses a low-pass filter (cutoff wavelength: 363.8 nm) having transmission characteristics different from those in FIG. 3 for the objective lens of the microscope. Is an actual fluorescence image of chrysotile and glass wool particles observed. In FIG. 7, laser-induced fluorescence from the particles was measured with a camera exposure time of 200 ns immediately after pulse laser irradiation. The left particle in the figure is chrysotile and the right is glass wool. Since the brightness of the glass wool particles is significantly higher than that of chrysotile while having the same particle area in the image, it can be seen that asbestos and glass wool can be easily distinguished even from the difference in brightness of the particles. When the fluorescence amount ratio per unit area of the clear part of each particle image was determined, the fluorescence amount ratio of glass wool was about 23 times that was close to 27 times shown in Table 1 with respect to chrysotile. Actually, even in the microscope system illustrated in FIG. 6, a large difference in the fluorescence amount ratio per unit area corresponding to the fluorescence amount ratio shown in Table 1 was confirmed. Even in the microscopic observation, a remarkable difference in the fluorescence ratio between chrysotile and glass wool was actually observed, so that the fluorescence ratio was also demonstrated in the microscope observation illustrated as an example of realizing a method for discriminating asbestos from the fluorescence quantity of laser-induced fluorescence. It was confirmed that asbestos can be clearly identified using as an index.

  The fluorescence amount ratio of 27 times the glass wool to chrysotile shown in Table 1 is the result of integrating the fluorescence spectrum obtained by using a low-pass filter with a cutoff wavelength of 360 nm as a spectroscope in a spectroscopic test from a wavelength of 350 to 700 nm. . In the microscopic test, all the fluorescence amounts having a wavelength of 363.8 nm or more were integrated, but a fluorescence amount ratio almost the same as the result of the spectroscopic test in Table 1 could be confirmed. The difference in the fluorescence amount ratio between the spectroscopic test in Table 1 and the microscopic observation in FIG. 7 is due to the difference in the wavelength region in which the above-described fluorescence spectrum is integrated. It depends on the difference in transmission characteristics, sensitivity characteristics of photodetectors, etc. The transmission characteristics of the low-pass filter used in the spectroscopic test of Table 1 and that used in the microscopic observation of FIG. 7 are greatly different in transmission characteristics with respect to wavelengths near the cutoff wavelength although the cutoff wavelength is the same wavelength range. Furthermore, the sensitivity characteristics with respect to the wavelength of the photodetector used in the spectroscopic test of Table 1 and the photodetector (CCD camera with photomultiplier tube) used in the microscope observation of FIG. 7 are also different. In the microscopic observation test, if the same low-pass filter transmission characteristics and photodetector sensitivity characteristics as those in the spectroscopic test in Table 1 are used, it is considered that the same value as the fluorescence amount ratio in Table 1 can be obtained by microscopic observation. It is done. It is expected that a difference occurs between the fluorescence amount ratios obtained from the spectroscopic test using the bulk sample in Table 1 and the microscope system for observing actual particles because the instrument functions are different. Therefore, when this technique is applied to the microscope system shown in FIG. 6, the fluorescence amount ratio per unit area between asbestos and other substances as an index for asbestos identification is the fluorescence calibrated by the actually used microscope system. It is recommended to use a quantitative ratio.

Industrial application fields

  According to the present invention, asbestos discrimination measurement, which has been difficult with the conventional method, is simple and quick. By incorporating the present invention into an asbestos measurement technique using a conventional microscope, asbestos can be determined numerically, so that an artificial error which is one of the major problems of the prior art can be avoided and the determination accuracy is improved. In addition, the measurement time can be greatly shortened. For example, in the present invention, asbestos type can be identified with a single sample, preparation for preparing a sample sample for each asbestos type to be measured, which is indispensable for analysis by a phase contrast microscope of the prior art, is unnecessary, and analysis work can be performed. Such time can be shortened.

  As an optimal application method of the present invention, characterized in that the amount of fluorescence per unit area of fine particles is used as an index for asbestos identification, an example applied to microscopic observation has been shown. However, the method of the present invention can be applied to measurement systems other than a microscope as long as the amount of fluorescence per unit area, which is a feature of the present invention, can be easily detected. Although it is a complicated system as a measuring device, in principle it can be applied to a light scattering type particle measuring device (particle counter) as long as the amount of fluorescence and the area or size of the particles that generate fluorescence can be measured.

  The present invention dramatically improves work efficiency and measurement accuracy related to asbestos measurement. As a result, the use of the present invention makes it possible to identify asbestos more accurately than in the past. Therefore, the present invention can be an effective means that can be used to solve environmental pollution problems related to asbestos. It is done.

Claims (6)

  An asbestos identification method that uses the amount of fluorescence per unit area of the substance-induced laser-induced fluorescence generated from the surface of fine particles of the substance in the specimen sample when the specimen sample is irradiated with laser light.   The asbestos identification method according to claim 1, wherein the measurement of the area of the fine particles in the sample is performed by microscopic observation. A first step of irradiating a specimen sample with laser light to generate substance-specific laser-induced fluorescence from the substance in the specimen specimen;
The laser-induced fluorescence generated in the microscope observation field is detected through an optical low-pass filter having light transmission characteristics in an arbitrary wavelength region longer than the irradiation laser wavelength, and the fluorescence from the fine particles is detected by a two-dimensional photodetector. The second step of image measurement,
A third step of determining an area for emitting laser-induced fluorescence of the fine particle from the fluorescent image of the fine particle obtained by image measurement, and an integrated fluorescence amount generated from the area;
Calculate the area where the microparticles generate fluorescence and the amount of fluorescence per unit irradiation area from the amount of fluorescence generated from the area, and compare it with the amount of fluorescence per unit area of asbestos obtained in advance under the same measurement conditions. Four steps,
An asbestos identification method comprising:   The asbestos identification method according to claim 3, further comprising measuring the number of identified asbestos particles in the fourth step. A first step of irradiating a specimen sample with laser light to generate substance-specific laser-induced fluorescence from the substance in the specimen specimen;
Laser-induced fluorescence generated in the microscope observation field is detected through a bandpass filter that has light transmission characteristics in a specific wavelength range longer than the irradiation laser wavelength, and the fluorescence from the fine particles is imaged with a two-dimensional photodetector. The second step to measure,
A third step of determining the area where laser-induced fluorescence of fine particles is emitted from the fluorescent image of the fine particles obtained by image measurement and the amount of fluorescence of a specific wavelength generated from the area,
Calculate the amount of fluorescence per unit irradiation area from the area where the fine particles generate fluorescence and the amount of fluorescence generated from the area, and compare with the amount of fluorescence per unit area of asbestos obtained in advance under the same measurement conditions Process,
An asbestos identification method comprising: A laser light source;
A low-pass filter or a band-pass filter having light transmission characteristics in an arbitrary wavelength region in the optical path of the objective lens;
A high-sensitivity CCD camera with a high-speed gate for observing laser-induced fluorescence separated by the low-pass filter or band-pass filter;
From the image of the fluorescence microscope having the above and the high-sensitivity CCD camera, the area of fine particles emitting laser-induced fluorescence and the amount of fluorescence per unit irradiation area are calculated from the amount of fluorescence generated from the area. An asbestos identification device comprising a measurement control device for determining the amount of fluorescence.

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