U.S. patent number 3,827,303 [Application Number 05/203,799] was granted by the patent office on 1974-08-06 for liquid chromatography.
This patent grant is currently assigned to Hitachi Ltd.. Invention is credited to Masaru Shiina.
United States Patent |
3,827,303 |
Shiina |
August 6, 1974 |
LIQUID CHROMATOGRAPHY
Abstract
A liquid sample for a liquid chromatography testing is prepared
by being injected in a tube containing development liquid to form
an elongated slug of liquid sample having development liquid at its
opposite ends. Thereafter, the development liquid with the
intermediate sample slug is transferred to a chromatographic column
for testing, so that only a very small quantity of sample is
employed correlated to only the exact needs of the chromatographic
column. The sample slug is injected by a hypodermic needle passing
through an elastomeric plug, so that the hole made by the
hypodermic needle is thereafter elastically sealed as the needle is
withdrawn. A transfer valve will selectively connect a reservoir
and suction device to the sample holding tube, and the pump and
chromatographic column with the sample holding tube to in the first
instance prepare the sample holding tube for injection of the
sample and in the second instance to transfer the development fluid
and injected sample to the chromatographic column. A plurality of
such sample holding tubes may be connected by valve means for
selective feeding to the chromatographic column.
Inventors: |
Shiina; Masaru (Katsuta,
JA) |
Assignee: |
Hitachi Ltd. (Tokyo,
JA)
|
Family
ID: |
14570356 |
Appl.
No.: |
05/203,799 |
Filed: |
December 1, 1971 |
Foreign Application Priority Data
|
|
|
|
|
Dec 16, 1970 [JA] |
|
|
45-111796 |
|
Current U.S.
Class: |
73/864.84 |
Current CPC
Class: |
G01N
30/16 (20130101) |
Current International
Class: |
G01N
30/00 (20060101); G01N 30/16 (20060101); G01n
001/00 () |
Field of
Search: |
;73/422G,423A,61,1C
;210/31C,198C |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Swisher; S. Clement
Attorney, Agent or Firm: Beall, Jr.; Thomas E.
Claims
What is claimed is:
1. A liquid chromatography apparatus, comprising: a chromatographic
liquid passage means to conduct liquid to a chromatographic column
for processing under high pressure a liquid sample undergoing
chromatography testing; sample passage means for holding a
development liquid in an elongated path; means for supplying
development liquid in said path; elastomeric seal means
intermediate the length of said path for receiving a hypodermic
needle passing therethrough to the interior of said sample passage
means for injecting a liquid sample to be analyzed within said
sample passage means to provide development fluid on each side of
an intermediate small quantity of liquid sample within said path;
said elastomeric means further sealing upon withdrawal of the
hypodermic needle; valve means having an open position providing
fluid communication between said sample passage means and said
chromatographic fluid passage, and a closed position fluid
isolating said sample passage means and said chromatographic fluid
passage; means including said valve means and pump means for
transferring the development liquid and intermediate injected
sample liquid from said path at a low pressure through the open
valve means to said chromatographic fluid passage at a higher
pressure for conducting the fluids to the chromatographic column;
said transferring means including pump means for circulating
development fluid through said open valve means and said sample
passage means to said chromatographic fluid passage; and said valve
means having a third selectable position fluid connecting said pump
means to said chromatographic fluid passage, and fluid isolating
said sample passage means from said pump means and chromatographic
fluid passage.
2. The device of claim 1, wherein said pump means circulates
development fluid through said sample passage means separate from
said chromatographic fluid passage only in the closed position of
said valve, and is isolated from said sample passage means in said
third position of said valve means.
3. A liquid chromatography apparatus, comprising: a chromatographic
liquid passage means to conduct liquid to a chromatographic column
for processing under high pressure a liquid sample undergoing
chromatography testing; sample passage means for holding a
development liquid in an elongated path; means for supplying
development liquid in said path; elastomeric seal means
intermediate the length of said path for receivng a hypodermic
needle passing therethrough to the interior of said sample passage
means for injecting a liquid sample to be analyzed within said
sample passage means to provide development fluid on each side of
an intermediate small quantity of liquid sample within said path;
said elastomeric means further sealing upon withdrawal of the
hypodermic needle; valve means having an open position providing
fluid communication between said sample passage means and said
chromatographic fluid passage, and a closed position fluid
isolating said sample passage means and said chromatographic fluid
passage; means including said valve means and pump means for
transferring the development liquid and intermediate injected
sample liquid from said path at a low pressure through the open
valve means to said chromatographic fluid passage at a higher
pressure for conducting the fluids to the chromatographic column; a
holding passage separate from said sample passage means and said
chromatographic fluid passage; said transferring means selectively
transferring the development fluid and liquid sample therein from
said sample passage means to said holding passage; said valve means
selectively fluid isolating said holding passage from said sample
passage means and said chromatographic fluid passage for storage;
and said valve means being operable to provide fluid communication
between said holding passage and said chromatographic fluid passage
for transferring the development fluid and liquid sample in said
holding passage to the chromatographic column through said
chromatographic fluid passage.
4. A liquid chromatography apparatus, comprising: a chromatographic
liquid passage means to conduct liquid to a chromatographic column
for processing under high pressure a liquid sample undergoing
chromatography testing; sample passage means for holding a
development liquid in an elongated path; means for supplying
development liquid in said path; elastomeric seal means
intermediate the lengto of said path for receiving a hypodermic
needle passing therethrough to the interior of said sample passage
means for injecting a liquid sample to be analyzed within said
sample passage means to provide development fluid on each side of
an intermediate small quantity of liquid sample within said path;
said elastomeric means further sealing upon withdrawal of the
hypodermic needle; valve means having an open position providing
fluid communication between said sample passage means and said
chromatographic fluid passage, and a closed position fluid
isolating said sample passage means and said chromatographic fluid
passage; means including said valve means and pump means for
transferring the development liquid and intermediate injected
sample liquid from said path at a low pressure through the open
valve means to said chromatographic fluid passage at a higher
pressure for conducting the fluids to the chromatographic column; a
plurality of substantially identical separate sample passage means
and corresponding injecting means; means, including said valve
means for separately connecting each of said sample fluid passage
means with said chromatographic fluid passage.
5. The device of claim 4, wherein said plurality of sample passage
means and their associated elastomeric sealing means are carried by
an indexable rotatable table having a plurality of indexed
positions corresponding in number to the number of sample passage
means carried thereby; each of said sample passage means having
first and second terminal fluid connecting ends, with all of said
first terminal ends being symetrically arranged with respect to the
axis of rotation to correspond to the indexed positions, and all of
said second terminal ends being symetrically arranged with respect
to the axis of rotation to correspond to the indexed positions; a
source of development fluid and pump means stationarily mounted
with respect to said indexable table at a position to be
successively fluid connected with respective ones of said first and
second terminal ends for each of said sample passage means for
respectively each of said indexed positions to fill said sample
passage means with development fluid successively; and said
transferring means including development fluid source means and
pump means stationarily mounted with respect to said indexable
table to be successively connected with one of said sample passage
means for each indexed position of said table to pump development
fluid and liquid sample held therein from said selected sample
passage means to said chromatographic fluid passage.
6. The device of claim 5, including a valve fluid interposed
between said first mentioned pump means and one end of the
associated selected sample passage means to be closed during
injecting to displace fluid from the other end of said the sample
passage means during injecting.
7. A liquid chromatography apparatus, comprising: a chromatographic
liquid passage means to conduct liquid to a chromatographic column
for processing under high pressure a liquid sample undergoing
chromatography testing; sample passage means for holding a
development liquid in an elongated path; means for supplying
development liquid in said path; elastomeric seal means
intermediate the length of said path for receiving a hypodermic
needle passing therethrough to the interior of said sample passage
means for injecting a liquid sample to be analyzed within said
sample passage means to provide development fluid on each side of
an intermediate small quantity of liquid sample within said path;
said elastomeric means further sealing upon withdrawal of the
hypodermic needle; valve means having an open position providing
fluid communication between said sample passage means and said
chromatographic fluid passage, and a closed position fluid
isolating said sample passage means and said chromatographic fluid
passage; means including said valve means and pump means for
transferring the development liquid and intermediate injected
sample liquid from said path at a low pressure through the open
valve means to said chromatographic fluid passage at a higher
pressure for conducting the fluids to the chromatographic column; a
plurality of said sample passage means; a corresponding plurality
of injecting means respectively for each of said sample passage
means; a corresponding plurality of said valve means directly
connected with respective ones of said sample passage means; pump
means; said transferring means fluid connecting said pump means
with said chromatographic fluid passage in a circuit through all
said valve means with said valve means closed separate from said
sample passage means; and each of said valve means independently
placing only its associated sample passage means in said circuit in
the open position.
Description
BACKGROUND OF THE INVENTION
It is conventional in liquid chromatography to provide a plurality
of sample measuring tubes, with the sample being sucked into the
tubes for subsequent carrying by development fluid to a
chromatographic column for analysis. A plurality, for example 12 or
24, of tubes have been used in the past for feeding selected
samples to a single chromatographic column.
A disadvantage with the above-described conventional system is that
a considerable amount of sample is wasted. If the volume of the
measuring tube is 0.5cc, about 3cc of sample quantity is necessary
although that quantity varies with the structure and arrangement.
It follows that a sample about five times as great of the sample
considered really necessary is wasted in such conventional devices.
Such wastage is undesirable in that sample material is generally
quite precious, particularly in the case where the sample material
comes from a living organism. Wastage has been a fatal defect of
the above-mentioned devices, particularly for certain
applications.
Further, these conventional processes require the preliminary
accurate determination of the volume of the measuring tubes for
improving the accuracy of the analytical result. For measuring
tubes, a Teflon tube of 0.5 to 1mm in diameter is generally
employed. Thus it is seen that if the sample quantity is to be
0.5cc, the necessary length of the tube is 640mm where the inside
diameter of the tube is 1mm. Restricting the error of the internal
volume of the tube to within 1 percent is a difficult task, which
calls for the employment of special techniques beyond those
employed in mass production.
SUMMARY OF THE INVENTION
It is an object of the present invention to overcome the
difficulties and disadvantages of the prior art by providing a
system wherein a small sample, correlated to the exact requirements
of a chromatographic column, may be injected into a carrier fluid
or development liquid so that it may subsequently be transferred to
the chromatographic column without wastage. This system of liquid
chromatography will have improved accuracy of analysis of a small
quantity of sample and a simplified procedure, because the sample
will always be introduced as a small and accurately defined
quantity.
Preferably, a development liquid is held in an elongated passageway
so that a liquid sample may be injected, preferably by a hypodermic
needle passing through an elastomeric plug, into the elongated
passageway at a precise location to displace development liquid
away from the precise location in only one direction, so that the
position of the sample slug is accurately determined within the
elongated passage. Thereafter, transfer means, including a transfer
valve, are employed to transfer the development liquid and
intermediate sample slug from the elongated passageway to the
chromatographic column. The accurate location of the sample slug
within the development liquid will enable processes to in turn
accurately locate the sample slug within the chromatographic column
by passing a predetermined quantity of fluid through the
chromatographic column during the transferring.
A plurality of such elongated passageways having the sample
injecting means may be provided, with a separate sample to be
selectively injected in each. With one embodiment, a holding
elongated passageway may be provided with the transfer means, and
filled with development liquid and sample liquid slug from a
selected one of the elongated passageways having the sample
injecting means. According to a further embodiment, a plurality of
transfer valves may be used with the transfer means so that only a
selected one of the elongated passages having the sample injecting
means may be connected at one time directly with the
chromatographic column for transferring the development liquid and
sample slug contained therein to the chromatographic column.
BRIEF DESCRIPTION OF THE DRAWING
Further objects, features and advantages of the present invention
will become more clear from the following detailed description of
the drawing, wherein:
FIG. 1 shows one embodiment of the present invention in somewhat
schematic form;
FIG. 2 shows a second embodiment of the present invention in
schematic form;
FIG. 3 shows in schematic form the transfer position of each of the
valves of the embodiment of FIG. 2;
FIG. 4 is a cross sectional view of a development liquid elongated
passageway having sample injecting means that may be used with the
embodiment of FIG. 1 or the embodiment of FIG. 2;
FIG. 5 shows a third embodiment of the present invention in one
position of its transfer valve;
FIG. 6 shows the transfer valve of FIG. 5 in a second position;
and
FIG. 7 shows the transfer valve of FIG. 5 in a third position.
DETAILED DESCRIPTION OF THE DRAWING
The present invention is concerned with liquid chromatography
capable of efficiently and simply introducing a minimum volume of
sample into a chromatographic column without wasting sample by
either introducing more sample than is needed into the column or by
requiring excess sample for processing to introduce a small
quantity in a circuit leading to a column.
In the first embodiment according to the present invention as shown
in FIG. 1, a chromatographic column 1 is schematically shown,
because it may be of any of the conventional types that are well
known in the art and its specific details form no part of the
present invention. The liquid enters the chromatographic column 1
by means of a liquid line 2 for analysis within the column in a
conventional manner, and thereafter exits through fluid line 3. The
pump 4 is supplied with liquid from the development liquid
reservoir 5 and is operated to pump development liquid through line
6, passage 7 of valve 8, and line 2 to the chromatographic column 1
for cleansing the same and removing traces of the previous sample,
if desired.
A sample slug is prepared within development liquid independently
of any analysis being carried on within the chromatographic column
or the above-mentioned flushing. For this purpose, there is
provided an elongated tubular passage 9 having terminal ends 10 and
11. For cleansing and filling this tubular passage 9 with
development liquid, a suction device 12 draws development liquid
from a reservoir 13, through line 14, through tubular passage 9,
through line 15, through valve 16, and through line 17 to the
expansible chamber 18 of the suction device 12. The suction device
12 may comprise an outer cup-shaped cylinder having its closed end
connected to line 17 and a manually operable piston contained
therein. When the tubular passage 9 has been filled with
development liquid and appropriately flushed with respect to any
residues from preceding samples, a sample is prepared in a
conventional manner within the expansible chamber of a hypodermic
needle 19 in an amount as accurately determined by the conventional
volumetric graduations of the hypodermic needle. Thereafter, the
operator will thrust the needle portion of the hypodermic needle
through an elastomeric sealing plug 20 so that the free exit end of
the needle will extend within the tubular passage 9. The point of
entry for the needle with respect to the tubular passage 9 is
precisely located with respect to the terminal end 10 by accurately
formed passageways therebetween. With the needle in this position,
the conventional plunger 21 of the hypodermic needle is manually
actuated to inject a precise amount of fluid sample within the
tubular passage 9 as determined visually by the aforementioned
graduations that are conventionally found on hypodermic needles of
this type. The inherent resistance of the suction device 12 or
actuation of the valve 16 to a closed position, whichever is
preferred, will assure that the development liquid within the
tubular passage 9 that is displaced by the injected sample will
only move away from the point of injection toward the terminal end
11, through the line 14 and into the reservoir 13. It is thus seen
that a slug of liquid sample is introduced into the tubular passage
9 to be contained on opposite ends by development liquid to form
fluid interfaces at these opposite ends; the fluid interface
closest to the terminal end 10 will be precisely located
independently of the volume of sample injected due to the
aforementioned flow of development liquid only through terminal end
11 during injection.
After the formation of the sample material slug within the
development liquid as set forth above, the tubular passage 9 will
ultimately be moved to the position of the identical tubular
passage 22. To accomplish this, a table 23 is rotatably mounted on
a stationary support 25 for indexing rotation about the axis of
shaft extension 26, as driven by a motor 27 through the
intermediary of meshing spur gears 28, 29 respectively drivingly
connected to shaft 26 and the shaft of motor 27. Two or more
tubular passages with associated support structure and elastomeric
sealing plugs for the hypodermic injection of sample material are
provided equally spaced, peripherally and radially with respect to
the axis of rotation, supportingly on the rotatable table 23 and
identical to each other. As shown by the mechanical schematic
interconnection, the valve 16 may be driven by the motor 27 for
automatic operation, although it is also contemplated that it may
be manually controlled, as may be the rotation of the table 23. A
plurality of O-rings 30 are fixedly inserted onto the tubular
passages in numbers corresponding to and positions corresponding to
the terminal ends of the tubular passages corresponding to the
terminal end 11 of the tubular passage 9 so as to be aligned with
selected ones for each indexed position of the table 23. Similarly,
O-rings 31 are provided for the other terminal ends corresponding
to the terminal end 10 of the tubular passage 9. While O-rings have
been specifically shown, it is further contemplated that a single
annular elastomeric gasket may be provided with a plurality of
through passages as required. In order to assure liquid seal, the
O-rings or gasket are made of elastomeric material such as rubber
or silicone rubber.
When the table 23 is rotated sufficiently to locate the tubular
passage 9 in the position of tubular passage 22, a pump 32 is
actuated to draw the development liquid and sample slug carried
therein from the tubular passage through line 33, passage 34 of
valve 8, and into the holding tubular passage 35. To assure that
the tubular passages and lines are always filled with development
liquid, a development liquid reservoir 36 is connected to line 37
communicating with the tubular passage in position 22. The position
of the sample slug within the holding tubular passage 35 may be
accurately located visually with manual control of the pump 32 or
automatically. With automatic operation, the volume of the line 33,
passage 34 and holding tubular passage 35 are accurately formed to
cooperate with the above-mentioned accurate location of the sample
slug within the tubular passage 9, so that a predetermined volume
change within the expansible chamber of the pump 32 will draw the
sample slug from the tubular passage 9, with accompanying
development liquid, and accurately locate it within the holding
tubular passage 35. For this purpose, the stroke of the piston 38
of the pump 32 is controlled by spring 39, its end positions within
the pump cylinder, and a rotatable operating cam 40. It is thus
seen that the spring 39 will actuate the pump during the
above-mentioned transfer operation and rotation of the cam 40 will
return the pump piston to its starting position. During the return
of the pump piston, the development liquid contained within the
pump expansible chamber may be discharged into a reservoir or the
like through a one-way valve, with a one-way valve also being
provided on the line 41 that is in communication with the passage
42 of the valve 8 shown connected with one end of the holding tube
passage 35.
With a sample slug accurately located within the holding tube
passage 35 according to the above description the spool 43 of the
valve 8 will be axially shifted by rotation of the engaged cam 44
into which it is biased by spring 45. The cam 44 is rotated by a
suitable motor 45 having a motor shaft 46 drivingly connected to
the cam 44 and the cam 40. In this manner, the valve spool 43 is
shifted so that valve passage 7 will only interconnect line 6 with
the right hand end of the holding tubular passage 35 as viewed in
FIG. 1 and the valve passage 34 will only interconnect the line 2
with the opposite end of the holding tube passage 35. With this
connection, the pump 4 may be actuated to pump development liquid
into the right hand end of the holding tube passage 35 to in turn
pump the sample slug from the holding tube passage 35 through the
valve passage 34, through the line 2, and into the chromatographic
column 1. As before, the pump 4 may be volumetrically calibrated to
automatically cease pumping when the sample slug is accurately
located in its proper position within the chromatographic column 1
by accurately volumetrically sizing the passage 34 and line 2,
which cooperates with the previously mentioned accurate positioning
of the sample slug within the holding tube passage 35. Thus it is
seen that only the exact quantity of sample material needed for
chromatographic analysis within the column 1 may be injected and
accordingly only this amount may be withdrawn from its source by
the hypodermic needle 19 with very little excess within the
hypodermic needle 19 accounting for wetting of the various
hypodermic needle surfaces and the small waste volume of the
needle.
According to the specific embodiment, there are provided twelve
passageways and injection means associated therewith corresponding
identically with the tubular passage 9 and sealing plug 20 so that
the table 23 is indexed in amount corresponding to the peripheral
spacing between these identical members to successively position
the members in position 22. Thus the tubular passages will take on
development liquid in the position shown for tubular passage 9 and
may take on sample material thereafter at this position or in any
position in one rotatable direction up to the position 22.
Preferably, the elastomeric sealing plug 20 is a silicone rubber
packing. Further, it is preferred to have the various lines and
portions of the passages constructed of Teflon tubing. Although
various reservoirs have been shown, only one reservoir may be
provided in actual practice.
FIG. 2 shows a further embodiment of a liquid chromatography
according to the present invention. This embodiment is provided
with three sample holding tubular passages 50a, 50b, 50c that are
arranged generally parallel to each other and respectively equipped
with sample injecting means 51a, 51b, and 51c, each of which may be
identical with the injecting means 20 of FIG. 1. The injecting
means 51a, 51b, 51c may cooperate with one or more hypodermic
needle injectors 52a, 52b, 52c. Preferably, disposable hypodermic
needles, which are conventional, may be employed with the present
invention to prevent cross contamination.
To control the various flow routes, there are provided a
corresponding number of valves 53a, 53b, 53c which may be identical
to the slide valve of FIG. 1, except that they are operated
preferably by biased springs 54a, 54b, 54c and solenoids 55a, 55b,
55c. In the position of the valve shown in FIG. 2, respective
suction devices 56a, 56b, 56c may be operated simultaneously or
selectively to draw development liquid from a source or reservoir
57 through the appropriate valve passages as schematically shown to
fill the sample holding tubes 50, 50b, 50c.
Thereafter, sample material is taken into one or more of the
hypodermic needles 52a, 52b, 52c in a known manner and transferred
as mentioned previously with respect to FIG. 1 through the
injecting means 51a, 51b, 51c into the holding tubular passages
50a, 50b, 50c with displaced development liquid returning to the
reservoir 57. Thus, a slug of sample material will be held in one
or more of the holding tubular passages as previously described
with the embodiment of FIG. 1. When any one of the valves 53, for
example 53a, is changed by actuation of its solenoid to the
position schematically shown in FIG. 3, the sample held therein
will be placed in liquid circuit with the chromatographic column
for transfer to the chromatographic column 58. With the valve 53a
in the position as shown schematically in FIG. 3, development
liquid from reservoir 59 will be moved by pump 60 through line 61,
the appropriate passage in the valve 53a, the holding tubular
passage 50a, the appropriate passage in valve 53a, and line 62 that
as shown in FIG. 2 with the valves 53b and 53c in their illustrated
position of FIG. 2 leads directly to the chromatographic column 58.
In a similar manner, if the valve 53b is changed from its position
as shown in FIG. 2 to a position as shown in FIG. 3 with the other
valves remaining in their FIG. 2 position, only the holding tubular
passage 50b will be directly in liquid circuit between the pump 60
and chromatographic column 58. Similarly, the above process is
repeated for the remaining holding tubular passages 50 regardless
of their number. Operation of the pump 60 and solenoids 55 may be
controlled either manually or automatically.
A further advantage of the present invention is that in both of the
embodiments of FIGS. 1 and 2, a valve is interposed between the
high pressure transfer pump 4, 60 and the injecting means 20, 51 so
that sample injecting may be carried out at any desired pressure,
for example advantageously at atmospheric pressure which greatly
facilitates the sealing function of the elastomeric plug with
respect to the hole left by the hypodermic needle, and the sample
collecting mechanism will not in any way dictate or compromise the
pressure to be used with the chromatographic column. Further, an
accurate amount of sample may be injected into the system according
to the graduations on the hypodermic needle as facilitated by the
above-mentioned reduced pressure preventing leakage and providing
normal back flow pressure for the hypodermic needle.
In FIG. 4, there is shown a detailed cross sectional view of a
preferred form for the tubular passage 9 and injecting means 20 of
FIG. 1, and the tubular passage 50 and injecting means 51 of FIG.
2. The element of FIG. 4 will be specifically described with
respect to its employment in the embodiment of FIG. 1. The coupling
members 70, 71 are externally threaded for a reception in
correspondingly formed holes within the table 23. Springs 72 and
73, upon coupling, will assure a tight sealing engagement between
the table portions and the tube carrying blocks 74, 75, with
O-rings 76 improving the sealing. The blocks 74, 75 are
respectively provided with coupling extensions 77, 78 for
telescopically receiving the adjacent terminal ends of tubes 79,
80. These tube ends along with the extensions 77, 78 are freely
slidable within the coupling members 70, 71.
The tube 79 is helically coiled about the core 81, which core is
integrally connected with the coupling member 70. The opposite end
of the tube 79 is telescopically received on a coupling nipple 82
of an injector block 83 that is provided with an internal passage
84 extending between the coupling nipple 82 and a corresponding
coupling nipple 85 receiving the other end of the tube 80. A guide
sleeve 86 is rigidly connected to the injector block 83 for
clamping therebetween a neoprene packing 87 so that the hypodermic
needle may pass through a passage 88 and the packing 87 in perfect
alignment with one leg of the passage 84. The tubes 79, 80 are
preferably constructed of Teflon having an accurate inside diameter
of 1mm and a combined length of approximately 650mm. The winding
core 81 is preferably cylindrical and about 15mm in outside
diameter and about 60mm in height.
While the device of FIGS. 5, 6 and 7 may be considered as a
separate embodiment, the slide valve disclosed therein and its
operation may be incorporated in each of the embodiments of FIGS. 1
and 2.
As shown in FIG. 5, the slide valves include a plurality of O-rings
90 fixedly carried by a reciprocating rod 91 carried within the
valve body to form a plurality of valve passages therebetween. The
rod 91 is reciprocated to the right by a solenoid 92 and to the
left by means of return spring 93.
With the valve in the position as shown in FIG. 5 and prior to
injection of a sample, the suction device 94 is operated to draw
development liquid from a reservoir 95 through the appropriate
passages of the valve to fill the holding tubular passage 96, which
is shown in more detail in FIG. 4. Subsequently, a precise quantity
of sample material is drawn into the hypodermic needle 97 as
determined by its graduations as mentioned before to later be
injected through the injection means 98 into the holding tubular
passage 96 while displacing development liquid back into the
reservoir 95. While the sample material is held as a sample slug
with development liquid on opposite sides within the holding
tubular passage 96, there may be considerable diffusion of the
sample throughout the development liquid over long periods of time
under certain circumstances, so that sample material may get into
unwanted areas and diffuse to an undesirable extent outside of the
holding tubular passage 96 for undesirable dilution of the mixture
within the holding tubular passage 96. To prevent this, the valve
is moved to the position of FIG. 6 by turning the threaded member
99 in one direction to unscrew it to the right as shown and
correspondingly move the rod 91 to the right due to the abutting
engagement between the increased diameter portion 150 of the rod 91
and the adjacent surface of the member 99. In this manner, the
valve passages are reoriented so that the terminal ends of the
holding tubular passage 96 are closed while the flow route between
the pump 100 with its reservoir 101 and the chromatographic column
102 is maintained open, as is particularly necessary with the
embodiment of FIG. 2.
When it is desired to transfer the sample held within the holding
tubular passage 96 to the chromatographic column 102, the solenoid
92 is energized to move the rod 91 against the bias of spring 93 to
its extreme right position as shown in FIG. 7. In this position, it
is seen that fluid from reservoir 101 will pass through pump 100
and the indicated passage in the valve of FIG. 7 to force the
sample and development fluid from the holding tubular passage 96
through the indicated passage within the valve to the
chromatographic column 102. Thus, a plurality of devices as shown
in FIG. 5 may be connected either in parallel or series to hold a
corresponding plurality of samples in readiness to be easily and
quickly transferred to the chromatographic column in succession by
operating the corresponding plurality of valves. In the manner
described above, the position of the valve of FIG. 6 will allow
holding of samples for many hours without contamination of other
areas or undue dilution so that the operation of the liquid
chromatography apparatus may be continuous without interruptions
for cleaning or removal of diffused samples.
Thus according to the present invention, as more fully described
above, there is provided a tube for holding development liquid and
a sample liquid in a flow route separated from the high pressure
flow route of a chromatographic column by the interposition of a
valve. The sample is injected in a precise amount by an injector
using only his precise amount, with small variations, so that the
thus injected slug of sample will be held with development liquid
on each side for subsequent transfer by operation of the valve to
the chromatographic column. With the present invention, it is
possible to use a quantity of sample material approximately
one-hundredth as small as the quantity of sample material used with
the above-mentioned prior art type of devices with equally
satisfactory results as to the sample material as reaches the
chromatographic column for analysis. The analytical accuracy of the
present invention is quite superior with respect to the prior art
in that the injection is accomplished with respect to a controlled
volume by reading the graduations carried by the hypodermic
injector to thus improve operational efficiency of sample measuring
over the conventionally required special techniques. Further, the
operator of the present device may function more easily and with
less experience than an operator of a corresponding prior art
device that is considerably more complex. Further, the
chromatography apparatus may operate continuously over a long
period of time since the sample can be maintained indefinitely
without diffusion beyond the holding passage as determined by both
liquid seals and valve seals.
Further variations, embodiments and modifications are contemplated
according to the broader aspects of the present invention while the
specifically described details are quite important in their own
right, according to the spirit and scope of the present invention
as defined by the following claims.
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