FIELD OF THE ART
[0001] This invention relates to a gas analysis device and a gas analysis method.
BACKGROUND ART
[0002] A quadruple mass spectrometer 20 has, as shown in Fig. 6, a measurement space (S)
into which a gas containing an object substance to be measured is introduced, and
an ionization unit 21, a quadrupole unit 22 and a detection unit 23 are arranged inside
of the measurement space (S). The quadruple mass spectrometer 20 has a principle wherein
the ionization unit 21 applies voltage to the gas introduced into the measurement
space (S) and gives and ionizes energy to the substance contained in the gas. Then,
the detection unit 23 detects the ionized object substance to be measured that passes
the quadrupole unit 22, and conducts a quantitative analysis on the object substance
to be measured based on a detection signal (refer to the patent document 1)
[0003] If the quantitative analysis is conducted on the object substance to be measured
of the mixed gas (hereinafter also called as the mixed gas) containing the object
substance not to be measured whose mass number is the same as or near the mass number
of the object substance to be measured by the use of the quadruple mass spectrometer,
the detection signal of the object substance to be measured is detected in a state
of being overlapped with the detection signal of the object substance not to be measured.
Then, the detection signal of the object substance not to be measured becomes an obstruction
so that it becomes difficult to conduct the quantitative analysis on the object substance
to be measured.
PRIOR ART DOCUMENTS
PATENT DOCUMENT
SUMMARY OF THE INVENTION
PROBLEMS SOLVED BY THE INVENTION
[0005] A main object of this invention is make it possible for a quadruple mass spectrometer
to relatively accurately conduct a quantitative analysis on an object substance to
be measured of a mixed gas containing an object substance not to be measured whose
mass number is the same as or near that of the object substance to be measured.
MEANS TO SOLVE THE PROBLEMS
[0006] In order to solve the above-mentioned problem, the applicant of this invention repeated
the experiment to conduct a quantitative analysis on an object substance to be measured
contained in the mixed gas by the use of the quadrupole mass spectrometer. As a result
of the repeated experiments to conduct the quantitative analysis on the object substance
to be measured contained in the mixed gas while changing the pressure in the measurement
space of the quadruple mass spectrometer, the applicant found a phenomenon that almost
no detection signal of the object substance not to be measured alone is detected when
the pressure in the measurement space becomes more than or equal to a predetermined
pressure.
[0007] Concretely, the experiment was conducted; while introducing a He gas (the object
substance not to be measured) whose mass number is 4 as being the carrier gas into
the measurement space of the quadruple mass spectrometer, D
2 (the object substance to be measured) whose mass number is 4 is introduced intermittently
at multiple times into the carrier gas, and a signal of He and a signal of D
2 are detected while applying a predetermined voltage to the gas by the ionization
unit. This experiment was conducted while decreasing the pressure in the measurement
space step by step in an order of 2.0Pa, 1.5Pa, 1.0Pa and 0.75Pa, then a graph shown
in Fig. 3 is obtained. In the graph shown in Fig. 3, a vertical axis indicates signal
intensity and a horizontal axis indicates elapsed time.
[0008] According to the graph shown in Fig. 3, it is proved that a signal (a detection signal
shown by "A" in Fig. 3) is detected for D
2 in spite of pressure drop. Almost no signal (a detection signal shown by "B" in Fig.
3) is detected for He in case that the pressure is 2.0Pa, however, an extremely big
signal is detected for He in case that the pressure is decreased to 1.0Pa.
[0009] There exists energy (ionization energy) necessary for ionization in a substance.
He is taken as an example, and will be concretely explained. A relation between the
energy (a horizontal axis) given to He and a number of ions (a vertical axis) per
unit area is a graph shown in Fig. 7. More specifically, the lower limit value of
the ionization energy of He is 24.6 eV, and if the energy of the lower limit value
is given, ionization starts and ionization is quickly promoted only when the energy
increases just a little around the lower limit value. Then, ionization of He is promoted
until the ionization energy that is more than or equal to a predetermined value (a
value indicated by "C" in Fig. 7) is given, and tends to be gradually suppressed when
the given energy becomes more than or equal to the predetermined value. The ionization
energy differs for each substance and the above-mentioned tendency also shows the
same for other substances.
[0010] The lower limit value of the ionization energy of D
2 is 15.467 eV so that it is smaller than the lower limit value (24.6 eV) of the above-mentioned
He. Then, in case that the energy given to He and D
2 in the measurement space is more than or equal to 15.467 eV and less than 24.6 eV,
only the signal of D
2 is detected. In other words, in the graph shown in Fig. 3, in case that the pressure
in the measurement space is set 2.0Pa, the reason why only the signal of D
2 is detected can be estimated that the energy given to the object substance to be
measured and the object substance not to be measured in the measurement space is more
than or equal to 15.267 eV and less than 24.6 eV. In addition, in the graph shown
in Fig. 3, when the pressure in the measurement space becomes less than or equal to
1.0 Pa, the signal intensity of He rapidly increases. This reason can be estimated
that the pressure in the measurement space rises and the energy given to He in the
measurement space becomes more than or equal to 24.6 eV so that ionization is rapidly
promoted.
[0011] More specifically, when the pressure in the measurement space is increased, the energy
given to the substance in the measurement space becomes smaller. When the pressure
in the measurement space is decreased, the energy given to the substance in the measurement
space becomes bigger. In a state wherein the pressure in the measurement space of
the quadruple mass spectrum is low (in a state wherein a vacuum degree is high), since
a number of the substance existing in the measurement space becomes small, it becomes
difficult for the substances to collide each other. This makes a state wherein a speed
of an electron to ionize the substance is fast, in other words, a state wherein the
energy given to the substance becomes big. Meanwhile, in a state wherein the pressure
in the measurement space of the quadruple mass spectrum is high (in a state wherein
the vacuum degree is low), since the number of the substance existing in the measurement
space becomes big, it becomes easy for the substances to collide each other. This
makes a state wherein the electron to ionize the substance is prevented from moving
so that the speed of the electron is slow, in other words, a state wherein the energy
given to the substance becomes small.
[0012] As mentioned above, the applicant of this invention successfully invented the present
claimed invention based on the knowledge obtained through the above-mentioned experiments.
[0013] More specifically, the gas analysis device in accordance with this invention comprises
a mixed gas generation mechanism that comprises a heating furnace that heats a crucible
where a sample is put while introducing a carrier gas to be an object substance not
to be measured, generates a sample gas that contains an object substance to be measured
by vaporizing at least a part of the sample and discharges a mixed gas comprising
the carrier gas and the sample gas, a quadruple mass spectrometer that has a measurement
space into which the mixed gas generated by the mixed gas generation mechanism is
introduced and that conducts a quantitative analysis on the object substance to be
measured by giving energy to the object substance to be measured and the object substance
not to be measured in the measurement space, and a pressure control mechanism that
adjusts pressure in the measurement space, and is characterized by that the pressure
control mechanism adjusts the pressure in the measurement space so as to change the
energy that is given to the object substance not to be measured in the measurement
space according to the lower limit value of ionization energy of the object substance
not to be measured.
[0014] In accordance with this arrangement, since the pressure in the measurement space
can be adjusted by the pressure control mechanism, it is possible to adjust the energy
given to the object substance not to be measured in the measurement space so as to
be near the lower limit value of the ionization energy of the object substance not
to be measured. Then, it is possible to lessen a signal of the object substance not
to be measured detected by the quadruple mass spectrometer in such a degree as not
to cause obstruction in conducting the quantitative analysis on the object substance
to be measured. As a result of this, even though the object substance not to be measured
(concretely, the object substance not to be measured whose mass number falls within
a range of ±4 of the mass number of the object substance to be measured) whose mass
number is near the mass number of the object substance to be measured is contained
in the mixed gas, it becomes possible to conduct the quantitative analysis on the
object substance to be measured accurately by the use of the quadruple mass spectrometer.
"Change in accordance with the lower limit value of the object substance not to be
measured" includes not only a case wherein change with referring to the lower limit
value alone of the object substance not to be measured but also a case wherein change
with referring to a difference between the lower limit value of the object substance
not to be measured and the lower limit value of the object substance to be measured.
[0015] If the pressure control mechanism is so configured to adjust the pressure in the
measurement space so as to make the energy given to the object substance not to be
measured in the measurement space equal to or less than the lower limit value of the
ionization energy of the object substance not to be measured, almost no signal of
the object substance not to be measured is detected by the quadruple mass spectrum
so that it is possible to conduct the quantitative analysis on the object substance
to be measured more accurately.
[0016] In addition, in case that the mixed gas generation mechanism generates the mixed
gas containing multiple object substances not to be measured, it is preferable that
the pressure control mechanism adjusts the pressure in the measurement space so as
to change the energy given to the object substance not to be measured having the lower
limit value of the ionization energy that is the lowest among the multiple object
substances not to be measured introduced into the measurement space according to the
lower limit value of the object substance not to be measured.
[0017] In accordance with this arrangement, all of the signals of the object substances
not to be measured detected by the quadruple mass spectrum become small in such a
degree as not to cause obstruction in conducting the quantitative analysis on the
object substance to be measured. Then, even though the mixed gas contains multiple
object substances not to be measured whose mass number is near that of the object
substance to be measured, it is possible to conduct the quantitative analysis on the
object substance to be measured relatively accurately by the use of the quadrupole
mass spectrum.
[0018] In addition, concretely the pressure control mechanism comprises a chamber to which
the quadruple mass spectrometer is connected and that has an internal space that communicates
with the measurement space of the quadruple mass spectrometer, an introducing line
that introduces at least a part of the mixed gas generated by the mixed gas generation
mechanism into the internal space of the chamber and a pressure regulating valve that
is arranged in the introducing line and that adjusts the pressure of the internal
space of the chamber.
[0019] In accordance with this arrangement, since the flow rate of the fluid flowing in
the introducing line is adjusted by the pressure control valve, it is possible to
adjust the pressure in the measurement space of the quadrupole mass spectrum.
[0020] In addition, in case that the carrier gas is a He gas and the sample gas contains
D
2 as being the object substance to be measured, although both the mass number of He
and the mass number of D
2 are four, it becomes possible to conduct the quantitative analysis on D
2 as being the object substance to be measured relatively accurately.
[0021] Furthermore, the heating furnace may be an impulse furnace, and the crucible may
be a graphite crucible. In this case, a gas containing D
2 to be the object substance to be measured and CO to be the object substance not to
be measured is generated as the sample. As a result of this, the mixed gas generation
mechanism may further comprise an oxidization unit that oxidizes the mixed gas discharged
from the heating furnace, a decarbon-dioxide unit that decarbon-dioxides the mixed
gas discharged from the oxidization unit and a dehydration unit that dehydrates the
mixed gas discharged from the decarbon-dioxide unit.
[0022] In case that the quantitative analysis is conducted on the mixed containing D
2 and CO by the quadrupole mass spectrum, the detection signal (a solid line in Fig.
5) of CO is detected in an overlapped state with the detection signal (a dashed line
in Fig. 5) of D
2 in the detection CH (m/z = 4) as shown in Fig. 5. However, in accordance with the
mixed gas generation mechanism, the mixed gas discharged from the heating furnace
is introduced into the quadrupole mass spectrum in a state wherein CO is generally
removed by each reaction so that it becomes difficult to detect the detection signal
of CO as shown by a dotted line in Fig. 5. As this result, it becomes possible to
conduct the quantitative analysis on D2 as being the object substance to be measured
relatively accurately.
[0023] Concretely, the oxidization unit may use the Schutze reagent as an oxidizing agent,
the decarbon-dioxide unit may use at least one selected among soda lime, sodium hydroxide
and activated alumina impregnated with sodium hydroxide as the decarbon-dioxide agent,
and the dehydration unit may use at least one selected from magnesium peroxide or
diphosphorus pentoxide as a dehydrating agent.
[0024] In addition, a gas analysis method in accordance with this invention is a gas analysis
method that uses a mixed gas generation mechanism that comprises a heating furnace
that heats a crucible where a sample is put while introducing a carrier gas to be
an object substance not to be measured, generates a sample gas that contains an object
substance to be measured by vaporizing at least a part of the sample and discharges
a mixed gas comprising the carrier gas and the sample gas, and a quadruple mass spectrometer
that has a measurement space into which the mixed gas generated by the mixed gas generation
mechanism is introduced and that conducts the quantitative analysis on the object
substance to be measured by giving energy to the object substance to be measured and
the object substance not to be measured in the measurement space, and is characterized
by that the energy that is given to the object substance not to be measured in the
measurement space is changed according to the lower limit value of ionization energy
of the object substance not to be measured by adjusting the pressure in the measurement
space.
[0025] In addition, the mixed gas generation mechanism may generate the mixed gas containing
the object substance to be measured and the object substance not to be measured whose
mass number falls within a range of ± 4 of the mass number of the object substance
to be measured and the lower limit value of whose ionization energy is bigger than
the lower limit value of that of the object substance to be measured.
EFFECT OF THE INVENTION
[0026] In accordance with the gas analysis device having this arrangement, it becomes possible
to conduct relatively accurately the quantitative analysis on the object substance
to be measured of the mixed gas containing the object substance not to be measured
whose mass number is the same as or near the mass number of the object substance to
be measured by the use of the quadrupole mass spectrum.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027]
[Fig. 1] A diagram schematically showing a whole configuration of a gas analysis device
of a first embodiment.
[Fig. 2] A block diagram showing a pressure control unit of the gas analysis device
in accordance with the first embodiment.
[Fig. 3] A graph showing a relation between a detection signal (signal intensity)
and an elapsed time (analysis time) of D2 and He.
[Fig. 4] A graph showing a relation between a detection signal (signal intensity)
and pressure in a chamber (pressure in measurement space) of D2 and He.
[Fig. 5] A graph showing a relation between a detection signal (signal intensity)
and an elapsed time (analysis time) of m/z = 4 obtained by introducing the mixed gas
generated by the mixed gas generation mechanism into the measurement space of the
quadrupole mass spectrum of the gas analysis device in accordance with the second
embodiment.
[Fig. 6] A diagram schematically showing an internal configuration of a quadrupole
mass spectrometer.
[Fig. 7] A graph showing a relation between energy given to He and an ion number per
area.
MODE FOR EMBODYING THE INVENTION
[0028] A gas analysis device in accordance with this invention will be explained with reference
to drawings.
[0029] The gas analysis device in accordance with this embodiment heats and melts a sample
such as steel or ceramics and conducts a quantitative analysis on an object substance
to be measured contained in a sample gas that is produced during the sample is heated
and melted.
[0030] <Embodiment 1> The gas analysis device 100 in accordance with this embodiment comprises,
as shown in Fig. 1, a mixed gas generation mechanism 10 that generates a mixed gas
that contains an object substance to be measured and an object substance not to be
measured, a quadruple mass spectrometer 20 that has a measurement space into which
the mixed gas generated by the mixed gas generation mechanism 10 is introduced, and
a pressure control mechanism 30 that adjusts pressure in the measurement space of
the quadruple mass spectrometer 20.
[0031] The object subject to be measured in this embodiment is concretely D
2. In addition, the object subject not to be measured is concretely He that has the
same mass number (4) as that of D
2 and that has the lower limit value (24.6 eV) of ionization energy that is bigger
than the lower limit value (15.467 eV) of the ionization energy of D
2. The object substance to be measured is not limited to D
2. In addition, the object substance not to be measured is not limited to He as far
as the mass number of the object substance not to be measured falls within a range
of ±4 of the mass number of the object substance to be measured and the lower limit
value of whose ionization energy is bigger than the lower limit value of that of the
object substance to be measured.
[0032] The mixed gas generation mechanism 10 comprises a heating furnace 11, an upstream
line L1 extending to an upstream side from the heating furnace 11, a carrier gas supplier
12 to be connected to a starting end of the upstream line L1 and a downstream line
L2 extending to a downstream side from the heating furnace 11.
[0033] The heating furnace 11 is, so called, an impulse furnace, and houses a crucible 11a
that puts the sample into inside of the furnace 11. The heating furnace 11 produces
Joule het by flowing the impulse current in the crucible 11a, and produces the sample
gas by vaporizing at least a part of the sample put into the crucible 11a. The sample
used in this embodiment is the sample that generates the sample gas containing D
2 as being the object substance to be measured by heating the sample in the heating
furnace 11. The crucible 11a may be a graphite crucible. In addition, the heating
furnace 11 may also be a high frequency induction heating furnace. In this case, the
crucible 11a may be a ceramic crucible.
[0034] The upstream line L1 introduces the carrier gas supplied from the carrier gas supplier
12 into the heating furnace 11. The carrier gas in this embodiment uses a He gas to
be the object substance not to be measured. The carrier gas is not limited to the
He gas, and may be an Ar gas.
[0035] The downstream line L2 discharges the mixed gas comprising the sample gas and the
carrier gas from the heating furnace 11. A dust filter 13 to remove dust such as soot
contained in the mixed gas is provided in the middle of the downstream line L2.
[0036] Since the quadruple mass spectrometer 20 has the same configuration as that of the
quadruple mass spectrometer 20 shown in Fig. 6, detailed explanation will be omitted.
[0037] The pressure control mechanism 30 comprises a chamber 31 having an internal space
that communicates with the measurement space (S) of the quadruple mass spectrometer
20, an introducing line L3 that bifurcates from the downstream line L2 and that introduces
at least a part of the mixed gas flowing in the downstream line L2 into the internal
space of the chamber 31, an exhaust line L4 that bifurcates from the downstream line
L2 and that exhausts remaining mixed gas flowing in the downstream line L2, a flow
rate control valve 32 that is arranged in the upstream side from the bifurcating point
of the downstream line L2, a pressure control valve 33 arranged in the introducing
line L3 and an exhaust pump 34 and a pressure sensor (P) to be connected to the chamber
31.
[0038] The chamber 31 comprises four ports. Each of the introducing line L3, the quadruple
mass spectrometer 20, the pressure sensor (P) and the exhaust pump 34 is connected
to each of the four ports respectively.
[0039] The flow rate control valve 32 is, so called, a needle valve. The flow rate control
valve 32 adjusts a flow rate of the mixed gas exhausted from the exhaust line L4 whose
terminal end is exposed to the atmosphere. Then, the flow rate control valve 32 controls
the flow rate of the mixed gas introduced into the introducing line L3.
[0040] The pressure control valve 33 is, so called a needle valve. The pressure control
valve 33 adjusts pressure in the internal space of the chamber 31. Then, the pressure
control valve 33 adjusts pressure in the measurement space (S) of the quadruple mass
spectrometer 20 that communicates with the internal space of the chamber 31.
[0041] The pressure sensor (P) measures the pressure in the internal space of the chamber
31. Then, the pressure sensor (P) measures the pressure in the measurement space (S)
of the quadruple mass spectrometer 20 that communicates with the internal space of
the chamber 31. In addition, the exhaust pump 34 exhausts the mixed gas introduced
into the internal space of the chamber 31. Concretely, a turbo pump 34a and a dry
pump 34b are arranged in serial.
[0042] In addition, the pressure control mechanism 30 further comprises a pressure control
unit 35 to be connected to the pressure control valve 33 and the pressure sensor (P).
The pressure control unit 35 is, as shown in Fig. 2, so-called a computer comprising
a CPU, a memory, an A/D converter and a D/A converter. The pressure control unit 35
executes programs stored in the memory and produces functions as a lower limit pressure
storing part 35a, a target pressure setting part 35b, a pressure value receiving part
35c and a valve opening position control part 35d.
[0043] The lower limit pressure storing part 35a stores the pressure (hereinafter also called
as the lower limit pressure) in the measurement space (S) wherein the energy that
is given to the object substance not to be measured in the measurement space (S) and
that is previously obtained for the object subject not to be measured becomes nearly
less than or equal to the lower limit value (for example, the lower limit value, less
than or equal to the lower limit value). A name of the object substance not to be
measured and the lower limit value are linked and stores in the lower limit pressure
storing part 35a.
[0044] The lower limit pressure can be mastered by conducting an experiment; the object
substance not to be measured (the carrier gas) is introduced into the measurement
space (S) of the quadruple mass spectrometer 20, the predetermined voltage is applied
to the gas introduced into the measurement space (S) by an ionizing unit while the
pressure is varied step by step and the object substance to be measured is introduced
to the object substance not to be measured for each step. Concretely, the lower limit
pressure of He as being the object substance not to be measured in this embodiment
may be selected from the pressure bigger than 1.5 Pa and smaller than or equal to
2.0 Pa. If referring to the graph shown in Fig. 4 obtained by an experiment wherein
an interval between the pressure fluctuations is further shorten than that of the
experiment obtained by the graph shown in Fig. 3, it turns out that the lower limit
of He is smaller than the lower limit of D
2 at least when the pressure in the measurement space (S) is 1.25 Pa. Then, then lower
limit pressure may be selected from the pressure less than or equal to 1.25 Pa.
[0045] In this embodiment, for example, He and 1.25 Pa are linked and stored in the lower
limit pressure storing part 35a. In case that it is not possible to specify a single
value as the value of the lower limit pressure, the lower limit pressure may be stored
as a range in the lower limit pressure storing part 35a.
[0046] In cast that an input signal indicating a name of the object substance not to be
measured contained in the mixed gas is received through an input means such as a key
board by an operator, the target pressure setting part 35b sets the lower limit pressure
linked with the object substance not to be measured stored in the lower limit pressure
storing part 35a as the target pressure. In case that the range of the lower limit
pressure is stored in the lower limit pressure storing part 35a, the pressure selected
in the range of the lower limit pressure (for example, the center value of the range)
may be set as the target pressure. In this embodiment, in case that the input signal
indicating He is received, 1.25 Pa is set as the target pressure.
[0047] The pressure value receiving part 35c receives the pressure value measured by the
pressure sensor (P). In addition, the valve opening position control part 35d adjusts
the valve opening position of the pressure control valve 33 so as to make the pressure
value received by the pressure value receiving part 35c approach the target pressure
value set by the target pressure setting part 35b.
[0048] In accordance with this arrangement, in case that quantitative analysis is conducted
on the mixed gas by the quadruple mass spectrometer 20, the pressure in the measurement
space (S) is adjusted so as to be less than or equal to near the lower limit value.
Accordingly, the detection signal of the object substance not to be measure is not
detected or only the degree of unobtrusive detection signal for the quantitative analysis
on the object substance to be measured is detected. Accordingly, it is possible for
the quadruple mass spectrometer 20 to relatively easily conduct the quantitative analysis
on the object substance to be measured.
[0049] The lower limit pressure storing part 35a stores the lower limit pressure of the
object substance not to be measured alone in this embodiment, however, the lower limit
pressure of the object substance to be measured may be stored. In this case, the target
pressure setting part 35b may set the value more than or equal to the lower limit
pressure of the object subject to be measured as the target pressure. With this arrangement,
it is possible for the quadruple mass spectrometer 20 to detect at least the detection
signal of the object substance to be measured.
[0050] <Embodiment 2> This embodiment is a modified embodiment of the mixed gas generation
mechanism 10 of the gas analysis device 100 in accordance with the above-mentioned
first embodiment. Concretely, the mixed gas generation mechanism 10 in accordance
with this embodiment is further provided with an oxidization unit 14 that oxidizes
the mixed gas discharged from the heating furnace 11, the decarbon-dioxide unit 15
that decarbon-dioxides the mixed gas discharged from the oxidization unit 14 and the
dehydration unit 16 that dehydrates the mixed gas discharged from the decarbon-dioxide
unit 15 (shown by dotted lines in Fig. 1) in the downstream line L2. Concretely, the
oxidization unit 14, the decarbon-dioxide unit 15 and the dehydration unit 16 are
arranged in the downstream line L2 in the downstream side of the flow rate control
valve 32 and in the upstream side from the bifurcated point between the introducing
line L3 and the exhaust line L4.
[0051] The oxidization unit 14 may use, for example, the Schutze reagent (concretely, the
Schutze reagent whose main component is iodine pentoxide) as an oxidizing agent.
[0052] The decarbon-dioxide unit 15 may use, for example, at least one selected among soda
lime, sodium hydroxide, and activated alumina impregnated sodium hydroxide as the
decarbon-dioxide agent.
[0053] The dehydration unit 16 may use, for example, at least one selected among magnesium
peroxide and diphosphorus pentoxide as the dehydration agent.
[0054] The gas analysis device 100 in accordance with this embodiment is suitable for conducting
the quantitative analysis on D
2 of the mixed gas containing D
2, CO, N
2 and He by the use of the quadruple mass spectrometer 20. Concretely, in case that
the impulse furnace is used as the heating furnace 11 and the graphite crucible is
used as the crucible 11a, since the mixed gas containing CO and N
2 is generated, the gas analysis device 100 is suitable for conducting the quantitative
analysis on the object to be measured contained in the mixed gas.
[0055] More specifically, if the quadruple mass spectrometer 20 conducts the quantitative
analysis on the mixed gas containing D
2, CO, N
2 and He, the detection signal solid line in Fig. 5) of CO is detected in an overlapped
state with the detection signal of D
2 (dashed line in Fig. 5) in detection channel CH of m/z = 4. Then, it becomes difficult
to conduct the quantitative analysis on D
2. However, in accordance with the gas analysis device 100 of this embodiment, the
mixed discharged from the heating furnace 11 is introduced into the quadruple mass
spectrometer 20 in a state wherein CO is generally removed, and almost no detection
signal of CO is detected in the detection channel CH of m/z = 4 as shown in dotted
line in Fig. 5.
[0056] If the sample gas containing D
2 as being the object substance to be measured is generated by putting Sn together
with the sample into the crucible 11a of the heating furnace 11 in accordance with
this embodiment and heating the crucible 1 1a, in case of conducting the quantitative
analysis on D
2 as being the object substance to be measured, it is difficult to be affected by the
detection signal of N
2.
[0057] <Other embodiment The quantitative analysis is conducted on the mixed gas containing
one object substance not to be measured in each of the above-mentioned embodiments,
however, the quantitative analysis may be conducted on the mixed gas containing multiple
object substances not to be measured. Each of the object substances not to be measured
is a substance whose mass number falls within a range of ±4 of the mass number of
the object substance to be measured and the lower limit value of whose ionization
energy is bigger than the lower limit value of that of the object substance to be
measured.
[0058] In this case, the pressure control mechanism 30 may adjust the pressure so as to
change the energy that is given to the object substance not to be measured having
the lowest lower limit value among the multiple object substances introduced into
the measurement space (S) of the quadruple mass spectrometer 20 according to the lower
limit value of the object substance not to be measured.
[0059] In addition, the present claimed invention is not limited to the above-mentioned
embodiments, and may be variously combined or modified without departing from a spirit
of the invention.
EXPLANATION OF CODES
[0060]
- 100 ...
- gas analysis device
- 10 ...
- mixed gas generation mechanism
- 11 ...
- heating furnace
- 11a ...
- crucible
- 14 ...
- oxidization unit
- 15 ...
- decarbon-dioxide unit
- 16 ...
- dehydration unit
- 20 ...
- quadruple mass spectrometer
- 30 ...
- pressure control mechanism
- L3 ...
- introducing line
- 31 ...
- chamber
- 32 ...
- flow rate control valve
- 33 ...
- pressure control valve
- 34 ...
- exhaust pump
1. A gas analysis device comprising
a mixed gas generation mechanism that comprises a heating furnace that heats a crucible
where a sample is put while introducing a carrier gas to be an object substance not
to be measured, generates a sample gas that contains an object substance to be measured
by vaporizing at least a part of the sample and discharges a mixed gas comprising
the carrier gas and the sample gas,
a quadruple mass spectrometer that has a measurement space into which the mixed gas
generated by the mixed gas generation mechanism is introduced and that conducts a
quantitative analysis on the object substance to be measured by giving energy to the
object substance to be measured and the object substance not to be measured in the
measurement space, and
a pressure control mechanism that adjusts pressure in the measurement space, wherein
the pressure control mechanism adjusts the pressure in the measurement space so as
to change the energy that is given to the object substance not to be measured in the
measurement space according to the lower limit value of ionization energy of the object
substance not to be measured.
2. The gas analysis device described in claim 1, wherein
the pressure control mechanism adjusts the pressure in the measurement space so as
to make the energy given to the object substance not to be measured in the measurement
space equal to or less than the lower limit value of the ionization energy of the
object substance not to be measured.
3. The gas analysis device described in claim 1 or 2, wherein
the mixed gas generation mechanism generates the mixed gas containing multiple object
substances not to be measured, and
the pressure control mechanism adjusts the pressure in the measurement space so as
to change the energy given to the object substance not to be measured having the lower
limit value of the ionization energy that is the lowest among the multiple object
substances not to be measured introduced into the measurement space according to the
lower limit value of the object substance not to be measured.
4. The gas analysis device described in either of claim 1 through 3, wherein
the pressure control mechanism comprises a chamber to which the quadruple mass spectrometer
is connected and that has an internal space that communicates with the measurement
space of the quadruple mass spectrometer, an introducing line that introduces at least
a part of the mixed gas generated by the mixed gas generation mechanism into the internal
space of the chamber and a pressure regulating valve that is arranged in the introducing
line and that adjusts the pressure of the internal space of the chamber.
5. The gas analysis device described in either of claim 1 through 4, wherein
the carrier gas is He gas, and
the sample gas contains D2 as being the object substance to be measured.
6. The gas analysis device described in either of claim 1 through 5, wherein
the heating furnace is an impulse furnace, and
the crucible is a graphite crucible.
7. The gas analysis device described in claim 6, wherein
the sample gas contains D2 to be the object substance to be measured and CO to be the object substance not to
be measured, and
the mixed gas generation mechanism further comprises an oxidization unit that oxidizes
the mixed gas discharged from the heating furnace, a decarbon-dioxide unit that decarbon-dioxides
the mixed gas discharged from the oxidization unit and a dehydration unit that dehydrates
the mixed gas discharged from the decarbon-dioxide unit.
8. The gas analysis device described in claim 7, wherein
the oxidization unit uses the Schutze reagent as an oxidizing agent.
9. The gas analysis device described in claim 7 or 8, wherein
the decarbon-dioxide unit uses at least one selected among soda lime, sodium hydroxide
and activated alumina impregnated with sodium hydroxide as the decarbon-dioxide agent.
10. The gas analysis device described in either of claim 7 through 9, wherein
the dehydration unit uses at least one selected from magnesium peroxide or diphosphorus
pentoxide as a dehydrating agent.
11. A gas analysis method that uses
a mixed gas generation mechanism that comprises a heating furnace that heats a crucible
where a sample is put while introducing a carrier gas to be an object substance not
to be measured, generates a sample gas that contains an object substance to be measured
by vaporizing at least a part of the sample and discharges a mixed gas comprising
the carrier gas and the sample gas, and a quadruple mass spectrometer that has a measurement
space into which the mixed gas generated by the mixed gas generation mechanism is
introduced and that conducts a quantitative analysis on the object substance to be
measured by giving energy to the object substance to be measured and the object substance
not to be measured in the measurement space, wherein
the energy that is given to the object substance not to be measured in the measurement
space is changed according to the lower limit value of ionization energy of the object
substance not to be measured by adjusting the pressure in the measurement space.
12. The gas analysis method described in claim 11, wherein
the mixed gas generation mechanism generates the mixed gas containing the object substance
to be measured and the object substance not to be measured whose mass number falls
within a range of ±4 of the mass number of the object substance to be measured and
the lower limit value of whose ionization energy is bigger than the lower limit value
of that of the object substance to be measured.