JP4042885B2 - Method and apparatus for monitoring a trace amount of harmful substances in the atmosphere - Google Patents

Description

【００２１】
表中、例えば「1.85E-11」は１．８５×１０^−１１を意味する。その他についても同様である。
尚、測定装置のネオンの初期キャリブレーション値（Ａ_０）は「4.20E-10」であった。したがって、この値を用いて塩化水素の補正値（Ｂ'_ｔ）は、Ｂ_ｔ×（Ａ_０／Ａ_ｔ）によって求められる。
【００２２】
この結果から分かるように、気圧の変動があった場合にはその前後で塩化水素ガスの質量分析装置の強度値Ｂ_ｔは変動するが、本発明の方法により補正されたもの（表中の補正値）は塩化水素の添加時以外はほとんど変化が無く一定の値を示した。また、塩化水素の濃度が５ｐｐｍの場合に相当するＢ_１は「2.00E-10」であり、０．５ｐｐｍの場合に相当するＢ_１は「2.00E-11」であるので、あらかじめ測定装置の警報1の設定として「2.00E-11」を、警報２の設定として「2.00E-10」を設定したところ、１４時、１５時及び１８時にそれぞれ警報１が作動し、１５時に警報２が作動した。
【００２３】
【発明の効果】
本発明の方法によれば、大気圧の変動等があっても大気中の微量の有害物質を長時間にわたって連続して、かつ大気圧の変化の影響を補正して正確に、簡単な方法で測定し、監視することができる。
【図面の簡単な説明】
【図１】本発明の微量有害物質の監視装置の構成図である。
【符号の説明】
１ イオン化手段
２ 質量分析手段
３ イオン検出手段
４ 登録手段
５ 補正手段
６ 判別手段
７ 送受信手段
８ 空気採取管
９ 切替器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for monitoring harmful gases and toxic gases in the atmosphere over a long period of time.
[0002]
[Prior art]
In recent years, smoke pollution from factories and incinerators, and air pollution caused by exhaust gases from automobiles and the like have become a serious problem. The types and dangers of trace amounts of harmful substances in such living and working environments are gradually becoming apparent. For example, chlorinated compounds such as vinyl chloride monomer, acrylonitrile-butadiene-styrene monomer, chlorine, hydrochloric acid, carbon tetrachloride, trichloromethane, trichloroethane, other halogen organic compounds, benzene, toluene, which are known as trace harmful substances Aromatic compounds such as xylene have become a problem with their toxicity at a much lower concentration than before. Specific examples include various problems such as the effects of aromatic compounds such as trace amounts of dioxins generated from incinerators of garbage, and chemical sensitivity due to formaldehyde generated from building materials. These have been damaged even at extremely dilute concentrations below ppm.
[0003]
[Problems to be solved by the invention]
Accordingly, it is necessary to continuously monitor and monitor the concentration of harmful gases and toxic gases in the extremely dilute atmosphere over a long period of time. For monitoring such a toxic substance with a dilute concentration, it is widely performed to measure the concentration using a mass spectrometer. The impact will appear and it will not be negligible. In order to perform accurate measurement excluding the influence of such fluctuations in atmospheric pressure, troublesome and time-consuming operations such as calibration and calibration operations are required, and there are many inconveniences for continuous monitoring in real time.
[0004]
[Means for Solving the Problems]
As a result of intensive studies in view of such circumstances, the present inventor has focused on the fact that the concentrations of neon and argon in the atmosphere are almost constant in the atmosphere, and the influence of atmospheric pressure fluctuations when monitoring trace substances in the atmosphere. The present invention has been completed by finding a method for removing the above and performing accurate measurement.
That is, the present invention relates to the measurement of the concentration of trace substances in the atmosphere using an analyzer , and the standard concentration of argon or neon in the atmosphere measured in advance by the analyzer at a specific pressure, and the analysis. device by the effect of pressure fluctuations in the air by correcting the ratio of argon or concentration of neon in the atmosphere for any time that is measured as an indication, traces of atmospheric measuring the concentration of trace substances in the air by the analyzer It is a monitoring method for harmful substances.
[0005]
Further, the present invention registers the concentration of argon or neon in the atmosphere in a standard state measured in advance at a specific atmospheric pressure by the analyzer when monitoring the concentration of trace harmful substances in the atmosphere using the analyzer. a registration unit, argon or concentration of neon in the atmosphere for any time as measured by the analyzer determines the ratio of the concentration of registered argon or neon in the registration unit, measured by the analyzer at the same time the An apparatus for monitoring a trace amount of harmful substances in the atmosphere, comprising correction means for correcting the influence of atmospheric pressure fluctuations by multiplying the concentration of the trace amount of harmful substances at an arbitrary time by this ratio.
[0006]
Further, the present invention relates to the concentration of argon or neon in the atmosphere in a standard state measured by the analyzer in advance at a specific atmospheric pressure and the concentration of the trace hazardous substance in the atmosphere in the monitoring of the concentration of the trace harmful substance in the atmosphere using the analyzer. And the concentration of argon or neon in the atmosphere at an arbitrary time is measured by the analyzer, and the ratio of the concentration of argon or neon registered in the registration means is obtained, and at the same time by the analyzer By multiplying the measured concentration of trace hazardous substances at any given time by this ratio, and subtracting the concentration of trace hazardous substances in the standard state registered in the registration means from this obtained value, It is a monitoring device for trace harmful substances in the atmosphere, characterized by comprising correction means for correcting the influence.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Mass spectrometers are widely used to measure trace substances in the atmosphere, but considering long-term monitoring over many months, atmospheric pressure fluctuates by a few percent and is a unit of dilute substances with concentrations lower than a percentage. Since the number of particles per deposit changes due to the influence of fluctuations in atmospheric pressure or fluctuations in the applied voltage value, correction of this measured value is necessary. On the other hand, on average, neon is contained in the atmosphere at a concentration of about 18 ppm and argon is about 9300 ppm, and neon and argon are hardly emitted from social industrial activities and human daily activities. These concentrations are kept almost constant and rarely fluctuate under the influence of the above-mentioned activities. The present invention relates to a method and an apparatus for measuring and monitoring harmful trace substances in the atmosphere by correcting a change in concentration due to atmospheric pressure fluctuations using neon or argon as an index.
[0008]
In the present invention, for example, if you want to monitor certain trace harmful substance B is advance first determine the concentration A ₀ neon or argon atmosphere as measured by a standard state in advance is, at any time t during monitoring by measuring the concentration a _t neon or argon, even when there is pressure fluctuations in the method of measuring the concentration B _t of the corrected trace hazardous substances in time using a change in a _t t for the a ₀ is there.
[0009]
More specifically, with measures the A _0, it may be set to limit concentration B ₁ in the atmosphere to be emitted to alert the particular trace harmful substance B to be monitored, harmful trace at any time t and thereafter continue monitoring measuring the substance concentration B _t and neon or argon concentration a _t. The corrected concentration (B ′ _t ) of the trace harmful substance even when there is a change in atmospheric pressure can be obtained by the following equation.
B ′ _t = B _t × (A ₀ / A _t )
This B ′ _t is compared with a preset size of B ₁ , and when B ′ _t exceeds B ₁ , an alarm or other information is issued or a necessary display is performed on the display.
[0010]
In the present invention, for example, if you want to monitor certain trace harmful substance B is to previously obtain the concentration A ₀ neon or argon atmosphere measured at standard conditions is first located in advance, any time during the monitoring by measuring the concentration a _t neon or argon at t, also measure the concentration B _t of the corrected trace toxic substances in the a ₀ time using a change in a _t for t when there is a change in air pressure Further, the concentration B ₀ of the trace harmful substance in the atmosphere measured in the above-mentioned standard state is obtained in advance, and the increase / decrease in the concentration of the trace harmful substance generated with respect to the concentration B ₀ of the trace harmful substance is measured. Is the method.
[0011]
More specifically, A ₀ and B ₀ are measured, and a limit concentration B ₁ in the atmosphere at which a warning is issued for a specific trace hazardous substance B to be monitored is set, and then monitoring is continued for an arbitrary time t. measuring the concentration B _t and neon or argon concentration a _t of trace harmful substances in. In the case of atmospheric pressure fluctuations, the amount of trace hazardous substances corrected by increasing or decreasing the concentration of trace hazardous substances generated relative to the concentration B ₀ of trace hazardous substances in the atmosphere measured in a certain standard state in advance. The concentration (B " _t ) is obtained by the following equation.
_{B "t = B t × (} A 0 / A t) -B 0
An alarm or other information when the B _"t beforehand by comparing the size of the set B ₁ and B" _t exceeds B _1, or performs necessary display on the display.
[0012]
In the present invention, neon or argon is used as an indicator, but neon is used because the concentration of trace substances to be monitored is low, particularly in the case of 1000 ppm or less, the concentration is close to the region. It is preferable to use argon when the concentration of the trace substance to be monitored is relatively high, particularly in the case of about 1000 ppm to about% order, because it is in a region close to the concentration similarly.
Moreover, the value of the concentration (B ₁ ) of the harmful gas that issues an alarm can be arbitrarily set according to the situation at that time, or a two-level or three-level alarm of a certain concentration and a higher concentration is issued. Two or more settings are possible.
[0013]
Various methods such as mass spectrometry, gas chromatography, infrared absorption spectrum, Fourier transform infrared spectrum, etc. can be considered for the measurement of trace substances in the atmosphere. In the present invention, mass is used for the measurement of trace harmful substances in the atmosphere. It is preferred to use an analytical device. In this mass spectrometer, the ionization means for applying a charge to a normal substance, the mass separation means for separating each molecular weight, the ion detection means for counting ions, the controller for promoting the action of the mass separation means, and the mass separation means are kept in vacuum. It is composed of a vacuum pump.
[0014]
In the present invention, various substances such as trace harmful substances sampled from the atmosphere are first ionized by ionization means. The ionization performed by the ionization means can be used in any of the hard ionization method and the soft ionization method. Anything can be used as long as the original parent molecule can be discriminated. However, if fragmentation is complicated, the spectrum continues to m / z values of close numbers so that the parent molecule can be found. It becomes difficult. Therefore, a soft ionization method that does not cause fragmentation, that is, a field ionization method, a field desorption ionization method, an atmospheric pressure chemical ionization method, an electrospray ionization method, and the like are preferable because ions of the parent molecule can be directly detected.
[0015]
Subsequently, the air containing the ionized harmful gas is separated by the mass separation means. Various mass separation means can be used in the present invention. For example, a magnetic field type or electric field type single focusing type or a double focusing type mass separation means using a magnetic field, a quadrupole type called a cue pole, that is, four metal rods are placed at the apex of a square. The type that selects ions that can pass through these four rods by flowing a high-frequency voltage with a direct current component to the opposite electrodes, in a cylindrical box called an ion trap, the electrodes are placed on the upper and lower sides, The ion which selectively takes out ions from the inside of the cylinder by the voltage of the high frequency and the direct current component, and the pulse ion generated by the laser pulse of strong energy such as a laser are introduced into the vacuum tube, and the flight time of a certain distance is measured. There are TOF methods for measuring molecular weight and FT-MS, but any mass separation means can be used here to select and separate ions. As long as, and may be increased the accuracy of separation of these in combination several ions.
For example, what is called MS-MS, MS-MS-MS, or triple quad, which obtains information on the structure of the molecule by analyzing the fragments after counting the parent ions by the soft ionization method can be used.
[0016]
Subsequently, the ions separated by the mass separation means are analyzed by the ion detection means. The ion detection means may be any means as long as it can count the intensity of the m / z value of the ion, and generally includes a Faraday cup, an ion or electron multiplier, a channeltron, a microchannel plate, and the like. Moreover, you may use combining these. In the present invention, air containing a trace amount of harmful substances in the air collected from the atmosphere is collected by a prefilter or the like, concentrated by a selective permeable membrane, etc., and then ionized by an ionization means, and ionized by a mass separation means. After selecting, it is preferable to count the number of ions by the ion detection means.
[0017]
FIG. 1 shows a block diagram of a monitoring device for trace harmful substances in the atmosphere according to the present invention. The apparatus of the present invention takes in trace amounts of harmful substances through the air sampling tube 8 and the switch 9, in addition to the ionization means 1, the mass separation means 2, and the ion detection means 3 that are ionized, separated and analyzed. The m / z value (mass number / charge number) of neon or argon ions in the standard state of the air, measured in advance at a specific pressure, eg 1 atm, the intensity (intensity) A ₀ , and a registration means 4 numerical value obtained by correcting the intensity at m / z values of trace harmful substances arbitrary measurement time t is capable of registering a reference value B ₁ for determining whether normal or not; the corresponding to m / z values of these ions with intensities a _t is registered in the registration means 4 of m / z values of the neon or argon ions at any time t during monitoring that are detected by the mass separation means 2 Standard condition A correction coefficient (A ₀ / A _t ) comparing each intensity A ₀ in the atmosphere is obtained, and the intensity B _t at the m / z value of a trace amount of harmful substance at an arbitrary time t is multiplied by this correction coefficient to obtain the trace amount. Compensation means 5 for obtaining the corrected intensity (namely, corrected concentration) B ′ _t of the toxic substance; comparing this B ′ _t with the reference value B ₁ to determine whether or not the trace toxic substance exists in the atmosphere above the limit intensity And a signal transmission means 7 for transmitting information obtained by the determination means 6 to a display device (not shown) such as a display or an alarm device (not shown). Is a monitoring device for trace amount of harmful substances in the atmosphere.
[0018]
Further, in FIG. 1, the apparatus of the present invention takes in a trace amount of harmful substances through the air sampling tube 8 and the switch 9, ionizes, separates, and analyzes the ionizing means 1, mass separating means 2 and ions as described above. In addition to the detection means 3; the m / z value (mass number / charge number) of the neon or argon ions in the atmosphere in a standard state measured beforehand at a certain pressure, for example 1 atm, the intensity Concentration) A ₀ , similarly m / z value (mass number / charge number) of ions of a trace amount of harmful substances in the atmosphere in a standard state measured in advance at a specific atmospheric pressure, intensity (ie, concentration) B _0, and any registration numerical value obtained by correcting the intensity at m / z values of trace harmful substance when measuring t is capable of registering one or more reference values B ₁ to determine normal or not Means 4; detected by the mass separation means 2 Standard state corresponding to the m / z values of these ions registered in the registration means 4 and the intensity A _t of m / z values of the neon or argon ions at any time t during Nitaringu atmospheric A correction coefficient (A ₀ / A _t ) for comparing each intensity A ₀ is obtained, and the correction of the trace harmful substance is performed by multiplying the intensity B _t at the m / z value of the trace hazardous substance at an arbitrary time t by this correction coefficient. Intensity (ie, corrected concentration) B ′ _t is obtained, and further, the intensity B ₀ of the trace harmful substance measured in the standard state is subtracted from the corrected intensity B ′ _{t of} the trace harmful substance, and the atmospheric air in a standard state measured in advance. A correction means 5 for obtaining a second correction intensity B " _t indicating the degree of increase or decrease in comparison with the intensity (that is, concentration) B ₀ of the trace harmful substance in the medium; comparing this B" _t with the reference value B ₁ As a result, trace harmful substances exist in the atmosphere exceeding the limit strength. Discriminating means 6 for discriminating whether or not it is appropriate; and signal transmitting means 7 for transmitting information obtained by the discriminating means 6 to a display device such as a display (not shown), an alarm device (not shown) or the like. And a monitoring device for trace amount of harmful substances in the atmosphere.
[0019]
【Example】
A model test for monitoring hydrogen chloride gas was conducted by the following method. Using a 1.56 × 10 ⁴ cm ³ stainless steel square container with an air inlet / outlet port, air is circulated through this container, and the air in this container is sampled every 30 minutes, causing harmful effects. Simultaneously with the concentration of hydrogen chloride as a gas, the concentration of neon was measured by a mass spectrometer over 12 hours, and the concentration of hydrogen chloride gas was monitored. In the middle of the monitoring, hydrogen chloride gas was injected into the inflowing air in three portions so that the concentration of hydrogen chloride was 0.5 ppm and 5.0 ppm. The mass spectrometer is a quadrupole type that detects using a channeltron, and the ionization method is an electron ionization method (EI method).
The measurement results for hydrogen chloride (m / z = 35) and neon (m / z = 20) at each measurement time are shown in Table 1 as intensity values of the mass spectrometer. During the measurement time, fluctuations in atmospheric pressure were observed at 16:30 and 21:00.
[0020]
[Table 1]

[0021]
In the table, for example, “1.85E-11” means 1.85 × 10 ⁻¹¹ . The same applies to other cases.
The initial calibration value (A ₀ ) of neon of the measuring device was “4.20E-10”. Therefore, using this value, the hydrogen chloride correction value (B ′ _t ) is obtained by B _t × (A ₀ / A _t ).
[0022]
As a result, as can be seen from, although the intensity value B _t of the mass spectrometer of the hydrogen chloride gas before and after in the case where there is variation in the air pressure fluctuates, as amended by the method of the present invention (correction in the table The value was a constant value with almost no change except when hydrogen chloride was added. Further, B ₁ corresponding to the hydrogen chloride concentration of 5 ppm is “2.00E-10”, and B ₁ corresponding to 0.5 ppm is “2.00E-11”. When "2.00E-11" is set as alarm 1 and "2.00E-10" is set as alarm 2, alarm 1 is activated at 14:00, 15:00 and 18:00, and alarm 2 is activated at 15:00 did.
[0023]
【The invention's effect】
According to the method of the present invention, even if there are fluctuations in atmospheric pressure, etc., a trace amount of harmful substances in the atmosphere is continuously applied over a long period of time, and the effect of changes in atmospheric pressure is corrected in an accurate and simple manner. Can be measured and monitored.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a trace hazardous substance monitoring apparatus according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ionization means 2 Mass spectrometry means 3 Ion detection means 4 Registration means 5 Correction means 6 Discrimination means 7 Transmission / reception means 8 Air sampling pipe 9 Switch

Claims (5)

In monitoring the concentration of trace harmful substances in the atmosphere using an analyzer,
And argon or concentration of neon in the atmosphere of a standard state measured in advance certain pressure by the analyzer, the ratio of argon or concentration of neon in the atmosphere for any time measured by the analyzer as an index correcting the effects of pressure fluctuations in the air, the monitoring method of trace harmful substances in the air to measure the concentration of trace harmful substances in the air by the analyzer.   The method for monitoring a trace amount of harmful substances in the atmosphere according to claim 1, wherein the analyzer is a mass spectrometer. In monitoring the concentration of trace harmful substances in the atmosphere using an analyzer,
Registration means for registering the concentration of argon or neon in the atmosphere in a standard state measured in advance by the analyzer at a specific pressure,
The concentration of argon or neon in the atmosphere at an arbitrary time is measured by the analyzer , a ratio with the concentration of argon or neon registered in the registration means is obtained, and at the same time, measured at the arbitrary time by the analyzer An apparatus for monitoring trace amounts of harmful substances in the atmosphere, comprising correction means for correcting the influence of atmospheric pressure fluctuations by multiplying the concentration of trace quantities of harmful substances by this ratio. In monitoring the concentration of trace harmful substances in the atmosphere using an analyzer,
Registration means for registering the concentrations of argon or neon in the atmosphere in a standard state and trace amounts of harmful substances measured in advance by the analyzer at a specific atmospheric pressure;
Measure the concentration of argon or neon in the atmosphere for an arbitrary time with the analyzer , determine the ratio with the concentration of argon or neon registered in the registration means, and at the same time, measure the concentration for the arbitrary time measured with the analyzer Correction means for correcting the effect of atmospheric pressure fluctuations by multiplying the concentration of trace harmful substances by this ratio and subtracting the concentration of trace harmful substances in the standard state registered in the registration means from this value obtained A monitoring device for trace amount of harmful substances in the atmosphere. Monitoring apparatus of trace harmful substances in the air according to claim 3 or 4, wherein the analyzer is a mass spectrometer.

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