U.S. patent number 4,597,943 [Application Number 06/676,200] was granted by the patent office on 1986-07-01 for apparatus for analyzing solid sample with supercritical fluid.
This patent grant is currently assigned to Japan Spectroscopic Co., Ltd., Morinaga & Co., Ltd.. Invention is credited to Muneo Saito, Kenkichi Sugiyama, Akio Wada.
United States Patent |
4,597,943 |
Sugiyama , et al. |
July 1, 1986 |
Apparatus for analyzing solid sample with supercritical fluid
Abstract
An apparatus for analyzing a sample with a supercritical fluid
includes a fluid container containing as an extraction solvent a
fluid obtained by compressing and liquefying a substance which is a
gas at ambient temperature and atmospheric pressure. A pump is
provided for drawing the fluid from its container through a suction
line and delivering it through a delivery line, while the heads of
the pump are cooled by a cooling device. An extraction mechanism is
provided for bringing the fluid in a supercritical state into
contact with the sample to be analyzed and extracting a specific
component or components from the sample. A trapping mechanism is
provided downstream of the extraction mechanism for collecting the
extracted component or components from the fluid. An analyzing
mechanism can be connected to the trapping mechanism by changeover
valves for analyzing the collected component or components.
Inventors: |
Sugiyama; Kenkichi (Yokohama,
JP), Saito; Muneo (Hachioji, JP), Wada;
Akio (Hachioji, JP) |
Assignee: |
Morinaga & Co., Ltd.
(Tokyo, JP)
Japan Spectroscopic Co., Ltd. (Hachioji, JP)
|
Family
ID: |
24713609 |
Appl.
No.: |
06/676,200 |
Filed: |
November 29, 1984 |
Current U.S.
Class: |
422/70; 73/61.52;
73/864.83; 210/659; 73/864.81; 210/198.2; 422/89 |
Current CPC
Class: |
G01N
30/28 (20130101); G01N 25/14 (20130101); G01N
30/02 (20130101); B01D 15/40 (20130101) |
Current International
Class: |
G01N
30/00 (20060101); G01N 25/14 (20060101); G01N
30/28 (20060101); G01N 25/00 (20060101); G01N
001/22 () |
Field of
Search: |
;422/70,89
;73/23.1,864.81,864.83 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Ito et al., "Head Space Gas Chromatographic Method . . . ", Nippon
Shokuhin Kogyo Gakkaishi, vol. 30, No. 3, 1983, pp. 133-139. .
Dennis R. Gere, "Supercritical Fluid Chromatography with Small
Particle Diameter Packed Columns", Anal. Chem. 1982, 54, 736-740.
.
Rawdon et al., "Supercritical Fluid Chromatography as a Routine
Analytical Technique", International Laboratory 1984, pp.
12-23..
|
Primary Examiner: Kellogg; Arthur
Attorney, Agent or Firm: Browdy and Neimark
Claims
What is claimed is:
1. An apparatus for analyzing a solid sample with a supercritical
fluid comprising:
a fluid container containing as an extraction solvent a fluid
obtained by compressing and liquefying a substance which is a gas
at ambient temperature and atmospheric pressure;
a pump of a reciprocating plunger type for drawing said fluid from
said fluid container through a suction line and delivering it
through a delivery line;
means for cooling a pump head portion of said pump to prevent
gasification of said fluid;
extraction means for bringing said fluid supplied through said
delivery line into contact with the sample, in a supercritical
state, to extract at least one component from said sample;
trapping means provided downstream of said extraction means for
collecting said at least one component from said fluid; and
a chromatograph which can be connected to said trapping means by
changeover valve means and which comprises a separating column,
distinct from said trapping means for separating said at least one
collected component from each other if said at least one component
is at least two components, and comprises a detector for detecting
said at least one component, said chromatograph further comprising
means for passing said at least one component from said trapping
means directly to said detector if said at least one component is
only one component.
2. The apparatus as set forth in claim 1, wherein said pump means
comprises a pump of the reciprocating plunger type.
3. The apparatus as set forth in claim 1, wherein said suction line
has a passage portion consisting of at least two branch lines, one
of said branch lines defining a passageway for said fluid, while
the other branch line having a solvent tank containing an entrainer
assisting said extraction, said solvent tank being divided into two
chambers by a movable or deformable partition, one of said chambers
containing said entrainer, while said fluid flowing into the other
chamber to exert pressure on said partition to force said entrainer
out of said one chamber, said one branch line having a valve, while
another valve being provided on said other branch line downstream
of said solvent tank, said valves being operable to supply said
fluid and said entrainer in a predetermined proportion so that a
mixture of said fluid and said entrainer may be supplied to said
pump.
4. The apparatus as set forth in claim 3, wherein said analyzing
means has a discharge line connected to said suction line between
said pump and a point at which said branch lines join each other to
form said mixture, said discharge line having a drain valve which
can be switched over to effect alternatively the discharge of said
fluid from said detector through said discharge line and the
recirculation of said fluid into said suction line.
5. The apparatus as set forth in claim 1, wherein said analyzing
mechanism comprises a liquid or gas chromatograph including a
separating column and a detector.
6. The apparatus as set forth in claim 1, wherein said changeover
valve means comprises a first changeover valve and a second
changeover valve, said delivery line and said chromatograph being
connected to said first changeover valve, said first and second
changeover valves being connected to each other by two connecting
lines, said trapping means being located on one of said connecting
lines, said second changeover valve forming a closed circuit in
which said extraction means is provided, said first and second
changeover valves being operable to effect alternatively the
connection of said delivery line, said extraction means and said
trapping means and the connection of said trapping mechanism to
said chromatograph.
7. The apparatus as set forth in claim 1, wherein said extraction
and trapping means and the lines associated therewith are all
provided with a temperature control device.
8. An apparatus for analyzing a sample with a supercritical fluid,
comprising:
a fluid container containing as an extraction solvent a fluid
obtained by compressing and liquefying a substance which is a gas
at ambient temperature and atmospheric pressure;
pump means for drawing said fluid from said fluid container through
a suction line and delivering it through a delivery line, said
suction line having a passage portion consisting of at least two
branch lines, one of said branch lines defining a passageway for
said fluid while the other branch line has a solvent tank
containing an entrainer assisting said extraction, said solvent
tank being divided into two chambers by a movable or deformable
partition, one of said two chambers containing said entrainer,
while said fluid flows into the other chamber to exert pressure on
said partition to force said entrainer out of said one chamber,
said one branch line having a valve, while another valve is
provided on said other branch line downstream of said solvent tank,
said valves being operable to supply said fluid and said entrainer
in a predetermined proportion so that a mixture of said fluid and
said entrainer may be supplied to said pump means;
means for cooling pump heads of said pump means;
extraction means for bringing the fluid supplied through said
delivery line into contact with the sample, in a supercritical
state, to extract at least one component from said sample;
trapping means provided downstream of said extraction means for
collecting said at least one component from said fluid; and
analyzing means which can be connected to said trapping means by
changeover valve means for analyzing said collected component from
said trapping means.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an apparatus for analyzing a sample with
a supercritical fluid. More particularly, it relates to an
apparatus of simple construction which employs a supercritical
fluid for extracting certain components from a solid sample, and
analyzing them.
2. Description of the Prior Art
While an organoleptic test by skilled persons has for a long time
been relied upon for the identification and evaluation of the
flavor (volatile components) of coffee bean powder, food,
cosmetics, perfumes, etc., attention has recently come to be
directed to the use of gas chromatography for the analysis and
evalution of those volatile components as described, for example,
in "Nippon Shokuhin Kogyo Gakkaishi", vol. 30, No. 3, pages 133 to
139 (1983). According to this method, volatile components are
collected from a sample by condensation or adsorption, and analyzed
and evaluated by an ordinary gas chromatographic technique.
This gas chromatographic method, however, still has a lot of
problems, since it employs a solid sample having a very low
concentration of volatile components and has to wait for the
volatilization of the volatile components for their collection. It
requires a sample quantity which is as large as at least 10 g. It
has a low degree of detection sensitivity. It requires a lot of
time for collecting the volatile components. It involves a
complicated procedure for the condensation or adsorption of the
volatile components.
A supercritical fluid obtained by compressing and liquefying carbon
dioxide or other substance which is a gas at ambient temperature
and atmospheric pressure is characterized by its excellent ability
to dissolve various kinds of substances. This characteristic is
utilized in a known technique for extracting components from
various substances as described, for example, in Anal. Chem., vol.
54, No. 4, pages 736 to 740, April 1982 and International
Laboratory, pages 12 to 23, June 1984.
As a supercritical fluid is very liable to gasification, however, a
lot of care is required for its transportation so that it may not
gasify. For example, it is necessary to use a pump having a high
compression ratio. An extremely large and complicated apparatus is,
therefore, required for the analytical operation which employs a
supercritical fluid, and is has hitherto been considered that a
supercritical fluid is difficult to employ for analytical
purpose.
SUMMARY OF THE INVENTION
Under these circumstances, it is an object of this invention to
provide a practical, supercritical fluid analyzer, i.e., a
practical apparatus for analyzing a sample with a supercritical
fluid, and especially an apparatus which includes a very simple
system for supplying a supercritical fluid to extract certain
components from a sample and analyze them effectively.
This object is attained by an apparatus comprising (a) a fluid
container containing as an extraction solvent a fluid obtained by
compressing and liquefying a gaseous substance which is gaseous at
ambient temperature and atmospheric pressure, (b) pressure pump
means for drawing the fluid from the fluid container through a
suction passage and delivering it through a delivery passage,
preferably a pump of the reciprocating plunger type, (c) means for
cooling the head of the pressure pump means, or preferably the pump
of the reciprocating plunger type, (d) an extraction mechanism by
which the fluid supplied through the delivery passage is brought
into contact with a solid sample in a supercritical state to
extract specific components from the sample, (e) a trapping
mechanism provided downstream of the extraction mechanism for
separating and collecting from the fluid the components extracted
by the extraction mechanism, and (f) a mechanism adapted for
connection to the trapping mechanism by changeover valve means for
analyzing the components leaving the trapping mechanism.
In accordance with one advantageous embodiment of the invention,
the suction line has a passage portion consisting of at least two
branch lines, one of the branch lines defining a passageway for the
fluid, while the other branch line having a solvent tank containing
an entrainer assisting the extraction, the solvent tank being
divided into two chambers by a movable or deformable partition, one
of the chambers containing the entrainer, while the fluid flows
into the other chamber to exert pressure on the partition to force
the entrainer out of the one chamber, the one branch line having a
valve, while another valve is provided on the other branch line
downstream of the solvent tank, the valves being operable to supply
the fluid and the entrainer in a predetermined proportions so that
a mixture of the fluid and the entrainer may be supplied to the
pump means.
According to a preferred form of the invention, the analyzing
mechanism has a discharge line connected to the suction line
between the pump means and a point at which the branch lines join
each other to form the mixture, the discharge line having a drain
valve which can be switched over to effect alternatively the
discharge of the fluid from the analyzing apparatus through the
discharge line and the recirculation of the fluid to the suction
line.
In the analyzing apparatus constructed as described above, the
analyzing mechanism comprises a liquid or gas chromatograph
including a separating column and a detector.
According to another advantageous embodiment of the invention, the
changeover valve means or selector valve means comprises a first
changeover valve (selector valve) and a second changeover valve
(selector valve), the delivery line and the analyzing mechanism
being connected to the first changeover valve, the first and second
changeover valves being connected to each other by two connecting
lines, the trapping mechanism being located on one of the
connecting lines, the second changeover valve forming a closed
circuit in which the extraction mechanism is provided, the first
and second changeover valves being operable to effect alternatively
the connection of the delivery line, the extraction mechanism and
the trapping mechanism and the connection of the trapping mechanism
to the analyzing mechanism.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of an apparatus embodying this
invention;
FIG. 2 is an enlarged cross sectional view of a pump employed in
the apparatus of FIG. 1;
FIG. 3 is a liquid chromatogram obtained by employing the apparatus
of this invention; and
FIG. 4 is a gas chromatogram obtained by employing the apparatus of
this invention.
DETAILED DESCRITPTION OF THE PREFERRED EMBODIMENTS
The invention will now be described more specifically by way of
example with reference to the drawings.
Referring first to FIG. 1, there is diagrammatically shown an
analyzer embodying this invention. It includes a CO.sub.2 cylinder
or bottle 2 containing liquefied carbon dioxide (fluid) obtained by
compressing and liquefying carbon dioxide which is a gas at ambient
temperature and atmospheric pressure. A suction pipe 4 extends into
the CO.sub.2 bottle 2 and has an end located in the vicinity of its
bottom. The suction pipe 4 is provided with a valve 6 which is
operable to draw liquefied carbon dioxide from the bottle 2 and
supply it to a pump 8 through the suction pipe 4.
The suction pipe 4 has three branch lines 10, 12 and 14. The branch
line 10 has a check valve 16 and a solenoid valve 18. The branch
line 12 has a solvent tank 20 and a solenoid valve 24 downstream of
the solvent tank 20. The branch line 14 likewise has a solvent tank
22 and a solenoid valve 26 downstream of the solvent tank 22. The
solvet tank 20 has a movable or deformable partition 28 which
divides the tank into two chambers in a gastight and liquidtight
fashion. The solvent tank 22 likewise has a movable or deformable
partition 30 which divides the tank into two chambers in a gastight
and liquidtight fashion. A solvent assisting extraction is supplied
into one of the chambers of the solvent tank 20 through a valve 32,
while a different solvent assisting extraction is supplied into one
of the chambers of the solvent tank 22 through a valve 34. A drain
valve 36 is provided for draining purposes when the solvent is
supplied into the solvent tank 20, and a drain valve 38 when the
solvent is supplied into the solvent tank 22.
The solvents are forced out of the solvent tanks 20 and 22 as the
liquefied carbon dioxides flows into the other chambers of the
tanks through the suction pipe 4, and supplied into a mixing tank
40 by means of the suction force of the pump 8 in quantities
controlled by the solenoid valves 24 and 26. The mixing tank 40 is
also supplied through the branch line 10 with the liquefied carbon
dioxide in a quantity controlled by the solenoid valve 18. The
solenoid valves 18, 24 and 26 are controlled by a control device 42
so that the quantities of liquefied carbon dioxide and one or two
extraction-assisting solvents flowing into the mixing tank 40 per
unit time may have an appropriate ratio to form a fluid mixture
having an appropriate concentration. The fluid mixture is supplied
to the pump 8 through a check valve 44. The mixing ratio of the
liquefied carbon dioxide and solvents can be varied as desired if
the durations of opening of the solenoid valves 18, 24 and 26 are
appropriately changed by the control device 42. This ratio can also
be varied with the lapse of time. The control of the valves by the
control device 42 is usually effected at a cycle of at least 0.1
second.
Referring to FIG. 2, the pressure pump means or pump 8 has three
axially reciprocable plungers 50 provided in a housing 46 and
maintaining a pin-point contact with a rotatable slanting plate 48.
The plungers 50 are located on a circle and have an angular
distance of 120.degree. from one another. The slanting plate 48
comprises a cut portion of a column having a cut surface lying at
an angle to the longitudinal axis of the column so that its
rotation may give axial movement to the plungers 50 contacting the
cut surface. The slanting plate 48 is rotated with a rotary shaft
54 supported by bearings and driven by a variable speed motor 52
supported on the housing 46 and connected to a speed reducing
mechanism. Three pump units 56 are supported on the housing 46.
Each plunger 50 is reciprocally movable into a solution chamber
(pumping chamber) 58 in one of the pump units 56. Each pump unit 56
has a suction valve 60 in a port to which a suction pipe 4a is
connected, and a delivery valve 64 in a port to which a delivery
pipe 62a is connected. The suction pipes 4a of the three pump units
56 are connected to the suction pipe 4 and the delivery pipes 62a
thereof to a main delivery pipe 62, as shown in FIG. 1.
The construction and operation of the pump 8 of the reciprocating
plunger type are detailed in U.S. Pat. No. 4,155,683 issued to one
of the inventors of this invention et al. The rotation of the
slanting plate 48 by the motor 52 causes the axial reciprocation of
the plungers 50 in the pump units 56 one after another (in a
clockwise or counterclockwise order in FIG. 1), whereby the pump 8
continuously draws the fluid through the suction pipe 4 and
delivers it through the delivery pipe 62.
The pump 8 has a cooling jacket 66 attached to the front side of
the housing 46 and covering the pump units 56. A cooling fluid,
which may be a gas or liquid, is supplied from a cooler 68 to the
cooling jacket 66, as shown in FIG. 1, to cool the pump heads of
the pump 8, i.e., the pump portions in which the fluid is
compressed (i.e., the solution chambers 58 of the pump units 56
into which the plungers 50 are movable). This cooling effectively
prevents the gasification of the fluid, which consists mainly of
liquefied carbon dioxide, when it is compressed in the chambers 58,
and thereby ensures normal operation of the pump. Moreover,
additional cooling of connection tubing, which is connected to the
pump heads of the pump 8, located in the vicinity of the pump
heads, for example suction pipes 4a, delivery pipes 62a, etc., is
more effective for preventing the gasification of the fluid.
A first six-way valve (i.e. six-port valve) 70 and a second six-way
valve (i.e. six-port valve) 72, which define a changeover valve
means, are provided downstream of the delivery pipe 62 and
connected in series to each other. As is well known, each of the
six-way valves 70 and 72 has six ports 74a to 74f or 76a to 76f and
each port can be connected to one of the two adjoining ports. In
other words, each valve enables changeover between the port
connection shown by solid lines in FIG. 1 and the port connection
shown by broken lines. The delivery pipe 62 is connected to the
port 74a of the first six-way valve 70 and the first six-way valve
70 is connected to the second six-way valve 72 by a connecting line
78 extending from the port 74b of the former to the port 76a of the
latter.
A closed circuit 80 is formed between the port 76c of the second
six-way valve 72 and the port 76f which can be connected to the
port 76a. The closed circuit 80 has a sample cartridge 82 in which
the sample to be analyzed can be placed. The sample cartridge 82
has a constant temperature maintained by a constant temperature
tank 84. The fluid is supplied into the sample cartridge 82 through
the delivery pipe 62, the first six-way valve 70, the connecting
line 78 and the closed circuit 80 and brought into contact with the
sample, in a supercritical state, i.e., at temperature and pressure
above its critical point to extract specific components from the
sample.
A purging gas line 86 is connected to the port 76e of the second
six-way valve 72 which can be connected to the port 76f. Liquefied
carbon dioxide can be supplied from the bottle 2 to the purging gas
line 86 through the valve 6 and the suction pipe 4 and into the
sample cartridge 82 through a pressure reducing valve 88, a valve
90 and the ports 76e and 76f to purge the sample cartridge 82 and
the closed circuit 80. The carbon dioxide which has purged the
sample cartridge 82 and the closed circuit 80 is discharged through
a drain line 92 connected to the port 76d which can be connected to
the port 76c to which the closed circuit 80 is connected.
A trap line 94 is provided between the port 76b adjoining the port
76c to which the closed circuit 80 is connected and the port 74e of
the first six-way valve 70. The trap line 94 has a trap column 96
filled with an appropriate material, such as an adsorbent. The
components extracted by the supercritical fluid in the sample
cartridge 82 are separated from the fluid while the fluid
introduced through the closed circuit 80, the ports 76c and 76b and
the trap line 94 is caused to pass through the trap column 96. A
constant temperature tank 98 is provided for maintaining the trap
column 96 at a constant temperature so that the components
collected by the material filling the trap column 96 may be
released therefrom when required.
Feed lines 100 and 102 are connected to the ports 74d and 74f,
respectively, which can be connected to the port 74e to which the
trap line 94 is connected. The feed lines 100 and 102 can be
selectively connected to an analyzing line 106 by a three-way valve
104. A mobile phase supply line 108 is connected to the port 74c
between the ports 74b and 74 d to supply a liquid or gaseous mobile
phase from a pump for liquid chromatography or a source of gas for
gas chromatography.
The analyzing line 106 can be connected to a separating column 114
by valves 110 and 112 so that the mobile phase containing the
specific components and introduced through the analyzing line 106
may be developed in the separating column 114 by a liquid or gas
chromatographic technique and separated into the individual
components which are detected by a detector 116 located downstream
of the column 114. In the event the mobile phase introduced into
the analyzing line 106 contains only one component to be analyzed,
the valves 110 and 112 are positioned as shown in FIG. 1 to supply
the mobile phase directly to the detector 116, e.g. an UV
detector.
A discharge line 118 extends from the detector 116 and has a
discharge valve 119 which is used to discharge the fluid when it is
not necessary to apply pressure thereto. In the event it is
necessary to apply pressure to the fluid, a servo pressure
controller 120 is provided for controlling the pressure of the
fluid upstream thereof and a three-way valve 122 is provided for
discharging the fluid through a drain line 124, or for connecting
the discharge line 118 to the suction pipe 4 between the mixing
tank 40 and the pump 8 through a check valve 126 so that the fluid
in the discharge line 118 may be drawn by the pump 8 through the
suction pipe 4 and delivered into the delivery line 62 to repeat a
cycle of extraction and trapping.
While in the apparatus as hereinabove described, the fluid or
liquefied carbon dioxide used as an extraction solvent is
continuously drawn from the CO.sub.2 bottle 2 by the pump 8 through
the suction pipe 4 and delivered into the delivery pipe 62, its
gasification can be effectively prevented by the use of the pump 8
of the reciprocating plunger type and the cooling of its pump
heads. The pump 8 of the reciprocating plunger type has a
compression ratio of, say, two or three times and never exceeding
several times. According to a salient feature of this invention, a
pump having such a low compression ratio can be effectively used to
deliver a liquefied fluid having a high pressure (about 70 atm. in
the case of liquefied carbon dioxide), only if the pump heads are
cooled. If the pump heads are not cooled, liquefied carbon dioxide
is difficult to feed through the pump 8. Although the foregoing
description has been based on the use of liquefied carbon dioxide
as an extraction solvent, it is also possible to use another fluid
obtained by compressing and liquefying another substance that is a
gas at ambient temperature and atmospheric pressure, e.g. propane
or ethylene.
The solvent tanks 20 and 22 are provided on the branch lines 12 and
14, respectively, and each tank contains a solvent assisting
extraction, i.e., an entrainer improving the efficiency of
extraction by liquefied carbon dioxide, such as ethanol, hexane or
water. The solenoid valves 18, 24 and 26 are controlled to provide
a fluid mixture having an appropriate mixing ratio, and the fluid
mixture is supplied through the pump 8 to perform an effective
extraction of the specific components from the sample in the sample
cartridge 82. No booster pump or the like is employed to supply the
entrainers into the high pressure suction pipe 4, but the pressure
of the liquefied carbon dioxide acting on the entrainers in the
solvent tanks 20 and 22 via the partitions 28 and 30 is effectively
utilized to supply the entrainers to the mixing tank 40 through the
solenoid valves 24 and 26. This arrangement drastically simplifies
the equipment for introducing the entrainers into the high pressure
line.
In the event the specific components are extracted from the sample
in the sample cartridge 82 by a supercritical fluid comprising
liquefied carbon dioxide, the ports of the first and second six-way
valves 70 and 72 are connected as shown by the broken lines in FIG.
1 and the fluid is supplied from the delivery pipe 62 to the sample
cartridge 82 in the closed circuit 80 through the ports 74a and
74b, the connecting line 78 and the ports 76a and 76f. The fluid
which has extracted the specific components from the sample in the
sample cartridge 82 is introduced into the trap line 94 through the
ports 76c and 76b and the components are separated from the fluid
in the trap column 96. The fluid, from which the components have
been separated, is caused to flow into the discharge line 118
through the ports 74e and 74f, the feed line 102, the three-way
valve 104 and the analyzing line 106, and discharged through the
three-way valve 122 or recycled therethrough into the suction pipe
4.
The components collected from the fluid are released from the trap
column 96 and separated into the individual components in the
separating column 114, and the individual components are detected
by the detector 116. Alternatively, if only one component is
involved for analysis, it is passed directly to the detector 116.
The release of the components from the trap column 96 is effected
by the control of its temperature by the constant temperature tank
98. Alternatively, it can be effected by connecting the ports of
the first and second six-way valves 70 and 72 as shown by the solid
lines in FIG. 1 and introducing a liquid or gas chromatographic
mobile phase into the trap column 96 through the mobile phase
supply line 108. The components released from the trap column 96
are caused to flow with the mobile phase through the ports 74e and
74d, the feed line 100, the three-way valve 104, the analyzing line
106, the valve 110, the separating column 114, the valve 112 and
the detector 116.
According to the apparatus of this invention as hereinabove
described, a fluid capable of forming a supercritical fluid is
effectively supplied by the pump 8 into the sample cartridge 82
defining an extraction mechanism in which the fluid forms a
supercritical fluid and effectively extracts the specific
components from the sample to be analyzed, and the components are
separated from the fluid in the trap column 96 on the trap line 94
and conveyed by a separately introduced mobile phase to an
analyzing mechanism defined by the separating column 114 and the
detector 116. The apparatus, therefore, enables the analysis of a
solid sample which has hitherto been considered difficult, and the
analysis and evaluation of the volatile components of foods,
chemicals, perfumes, fats, etc., while employing the sample in a
very small quantity.
FIGS. 3 and 4 show by way of example the chromatograms obtained by
employing the apparatus of this invention for analyzing the flavor
of coffee bean powder. FIG. 3 shows the results of liquid
chromatography, and FIG. 4 the results of gas chromatography. The
conditions of the analyses were as follows:
______________________________________ (1) Conditions of Extraction
Sample cartridge (82) Sample weight: 0.4 g. Cartridge scale: 4.6 mm
dia. by 5 cm long. Temperature: 48.degree. C. CO.sub.2 : Supplied
at a pressure of 120 kg/cm.sup.2 and a flow rate of 5 ml/min. Trap
column (96) Packing agent: Micro-beads of silica (200 mesh). Column
scale: 4.6 mm dia. by 50 cm long. Temperature: 10.degree. C. (2)
Conditions of High-Performance Liquid Chromatography Separating
column: Packed with Fine-pak-silica .RTM. (JAPAN SPECTROSCOPIC CO.,
LTD.) Column scale: 4.6 mm dia. by 25 cm long. Mobile phase
Methanol/water = 45/55. solvent: Detector: UV detector (UVIDEC-II
.RTM.; JAPAN SPECTROSCOPIC CO., LTD.), 280 nm, 0.64 AUFS. (3)
Conditions of Gas Chromatography Separating column: Thermon 600T
(Shimazu Seisakusho LTD. Japan) Column scale: 0.5 mm dia. by 50 m.
Carrier: 1 kg, split 1:30. Temperature: 70.degree. C. to
210.degree. C. at 4.degree. C. /min. Absorbing column: 3 mm dia. by
20 cm long [tenax GC (AKZO Research Laboratories) 15 cm],
200.degree. C., 1 min., inlet.
______________________________________
As is obvious from FIGS. 3 and 4, the apparatus of this invention
enables the effective extraction and analysis of the specific
components by a supercritical fluid, while employing the sample in
a quantity which is as small as 0.4 g.
While the invention has been described with reference to a
preferred embodiment thereof, it is to be understood that it is not
intended for limiting the scope of this invention, but that
modifications or variations may be easily made by anybody of
ordinary skill in the art without departing from the spirit and
scope of this invention which are defined by the appended
claims.
For example, while the pump 8 of the reciprocating plunger type can
advantageously be used, it is equally possible to employ other pump
means. Although the pump 8 has been described as comprising three
pump units 56, it is possible to use a pump of the reciprocating
plunger type havng one or two pump units or four or more pump
units. Although the suction pipe 4 has been described as having
three branch lines 10, 12 and 14, it is sufficient to provide two
branch lines if only one kind of entrainer is employed. It is, of
course, appropriate to provide four or more branch lines if
required. Moreover, a wide variety of modifications may be possible
for the cooler which supplies the cooling fluid to the cooling
jacket 66 on the pump housing 46, or for the first and second
six-way valves.
While the constant temperature tanks 84 and 98 have been shown only
for the sample cartridge 82 and the trap column 96, respectively,
it is desirable to control the temperature of the closed circuit 80
and the trap line 94 too, in order to maintain the supercritical
state effectively. It would, moreover, be advisable to control the
temperature of the six-way valves 70 and 72 and the associated
lines if required.
* * * * *