Note: Descriptions are shown in the official language in which they were submitted.
1312480
AUTOMATED SAMPLER-INJECTOR APPARATUS
AND METHOD FOR SAMPLING A QUANTITY
OF SAMPLE AND TESTING PORTIONS OF
-SAID QUANTITY
______________________________________
~ 1 Introduction
. _ _
The present invention relates to improvements
in automated sampling apparatus and methods for taking
a quantity of sample from multiple sources for testing
in analytical instruments. More particularly the
present invention relates to an automated sampling
apparatus and method of sampling for repetitive
injection of portions of a sampled quantity into a
liquid chromatograph device for analysis.
.~
1 3 1 2480
1 Background of the Invention
Numerous known patented devices exist in the
art of automated sampling of multiple sources for
analysis in liquid chromatograph devices.
In early liquid sampling devices, typified in
United States Patents 4,478,095 to Bradley, et al, and
3,918,913 to Stevenson et al., a plurality of vials
containing samples were disposed around the periphery
of a rotatable turntable or carousel.
These devices used a positive displacement
system for drawing up a quantity of sample from the
vials, wherein a co-axial needle was used to pierce a
septum covering the vials, and air or an inert gas
injected through an outer annulus within the co-axial
needle to force a quantity of sample up through the
inner annulus of the needle into a conduit means.
The quantity of sample was then conveyed by
the conduit means to an injector valve, and into a
sample loop affixed at both its inlet end, and outlet
end, to such injector valve. The rotary component of
the valve was then rotated to connect one end of the
sample loop with a suppiy of pressurized solvent, and
the other end of the sample loop was placed in
communication with a conduit leading to a liquid
chromatograph column. The quantity of sample was
1312480
1 thereby flushed from the sample loop by the pressurized
solvent, and thusly flowed into the chromatograph
column together with the solvent for analysis.
Fig. 1 of U.S. Patent 4,478,095 to Bradley et
al clearly shows such a device, having a conduit 49
leading from the vials to an injector valve 51, and
also a syringe means 139 for aiding the withdrawal of
the quantity of sample from the vials 27. The quantity
of sample is drawn into the sample loop 143 connected
to the injector valve 51 r and the valve is then
switched to connect a pressuriæed flow of solvent in
conduit line 153, which then flushes the quantity of
sample into conduit line 155 for transfer to a liquid
chromatograph column.
Figs. 4 and 5 of U.S. Patent 3,918,913
disclose a similar device for withdrawing a quantity o~
sample from a vial 11, and injecting such quantity into
a liquid chromatograph column 6, operating on the
identical principal.
The problem with such prior art devices was
that a portion of the sampled quantity always lay in
the conduit line leading from the sample container to
the injection valve, and was never able to be injected
into the column for analysis.
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1 Accordingly, only sample volume which lay in
the sample loop (line 5 in Figs. 4 and 5 of Stevenson
et al, and line 143 in Fig. 1 of Bradley et al) was
able to be injected into the liquid chromatograph
column for analysis, and the portion of the sampled
volume lying in the conduit line leading to the valve
(conduit line 21 in Figs. 4 and 5 of Stevenson et al,
and conduit line 49 of Fig. 1 of Bradley et al) was
unusable, and had to be purged from the system by means
of flushing solvent, as disclosed in U.S. Patent
4,478,095 to Bradley et al, to avoid contamination with
a subsequently drawn quantity of sample from another
sample container.
In some applications for sampling devices, it
is extremely critical to avoid any loss of the sampled
quantity, since as much as possible of the sampled
quantity is desired to be injected into the liquid
chromatograph for analysis. For example, in hospital
and medical use, the quantity of sample contained in
vials where the sample is a blood, tissue, or bone
marrow specimen obtained from a child, or a small
localized area of infection in an individual, may
indeed be a very small quantity, often much less than
20-100 microliters.
1312480
1 Accordingly, as much as the sample must be
injected as possible into the liquid chromatograph
column to obtain as accurate an analysis as possible of
the components within the sampled quantity.
In order to overcome the problem of sample
loss, it is known in the prior art to incorporate the
sampling conduit line as part of the sample loop,
whereby all of the sampled quantity can then be
injected through the injector valve into the liquid
chromatograph column.
U.S. Patent 4,242,909 to Gundelfinger,
assigned to Rheodyne Incorporated, discloses such a
device. Accordingly, in Figs. 7 and 8 thereof, an
injector valve 156 in a load position allows the valve
ports on the injector valve to connect a syringe means
19 with an overfill loop 18 whose loop end 22 is
inserted into a sample container 12 to allow the
syringe means 19 to withdraw a sample therefrom. $he
injector valve 156 when switched to an inject position,
operatively disconnects the overfill loop 18 with the
syringe means 19 and connects one end thereof 44 to a
pressurized flow of solvent, and the other end (i.e.
the loop end 22) is allowed to be inserted into a loop-
end coupling 152 in injec~or valve 154, which is in
fluid communication with the liquid chromatograph
column 14.
-- 6 --
1 3 1 2480
1 While the Gundelfinger configuration
completely overcomes the problem of sample loss, since
all of the sampled quantity drawn into the overfill
loop 18 is injected into the injector valve 154 and
into the liquid chromatograph column 14, and further
that by placing the loop end 22 directly into the
injector valve 154, certain other advantages discussed
below are realized, a definite and important drawback
of the Gundelfinger configuration lies in the fact that
all of the quantity drawn into the overfill loop 18
must be injected at one time into the injector valve
154 and chromatograph column. Accordingly, because the
overfill loop 18 comprises part of the flow line
between the high pressure pump 32 and liquid
chromatograph column, no capability exists for
repetitively injecting aliquot portions of the sampled
quantity from the overfill loop 18 to the chro~atograph
column. This is important, since duplicate or
triplicate results from chromatograph testing cannot be
obtained, which greatly lessens confidence in the
single result thereby obtained.
The Gundelfinger type configuration
accordingly presents serious disadvantages then in
pharmaceutical or immunilogical testing applications,
since fre~uently the testing regimen specified in
-- 7 --
13l248o
1 laboratory procedures requires repetitive liquid
chromatograph teseing on the same sampled quantity.
Accordingly, for the Gundelfinger configuration to
accomplish this result, only a portion of the sample
contained within the sample container can be withdrawn
at one time for analysis. This requires much greater
complexity in the apparatus to accomplish this result,
and the applicant herein presently knows of no device
using such configuration that has been able to
accomplish this result.
Accordingly, a real need exists in the art
for a samplin~ device that is able to utilize all of
the sampled quantity for subsequent injection into a
liquid chromatograph column without sample loss, and
further be able to repetitively inject equal portions
of the same sampled quantity into a liquid
chromatograph column to thereby improve the reliability
in the results obtained from such liquid chromatograph
testing.
As mentioned above, the placement of a loop-
endt or injector tube, directly into an injector valve,
wherein the loop-end within the valve is then allowed
to be in direct fluid communication with the sample
loop, avoids the problem that of the earlier valve
designs had in that some of the sample would remain in
-- 8 --
13~24~o
1 the flow passage of the injector valve between the
injector tube and the sample loop, and thus not be
injected. This advantage is known in the art, and is
clearly disclosed in U.S. Patent 4,182,184 to Bakalyar,
also assigned to Rheodyne, which relates to an injector
valve specifically incorporating such feature.
Such patent discloses a manual method,
however, for use of such injector valve wherein a
micro-syringe 52, as shown in Fig. 6 thereof, is
inserted into the injector valve 50 to inject an entire
previously sampled quantity into a sample loop 72, and
the rotor 58 of the injector valve 50 is rotated, as
shown in Fig. 8 thereof, to connect the sample loop 72
at one end with a pressurized source of solvent, and at
the other end with a liquid chromatograph column, to
flush the sample into the liquid chromatograph column.
The Bakalyar patent does not, however, teach
or disclose the method of injecting aliquot portions
down to 1-10 microliters in volume from a single
sampled quantity of sample previously drawn into the
micro syringe, and then switching the injector valve 50
from a load position to an inject position and back to
a load position, to repetitively inject portions of
such sampled quantity into the liquid chromatograph
column. In fact, such patent clearly discloses at page
- 9 - 1 3 ~ 24 8 0
1 3, lines 65-68 thereof that the sample loop is always
made long enough to contain a volume of liquid greater
than the largest volume to be introduced by the micro
syringe 52.
To achieve the ability to repetitively inject
microliter portions of a sampled quantity into the
injection valve from a syringe means, automation of the
injection valve and syringe means are required, since
manual sensitivity is not adequate to dispense such
small volumes from the micro syringe into the injection
valve.
It was not immediately apparent then from the
prior ar~ how the Bakalyar injection valve with i~s
above advantages may be automated. This was due to the
fact that in most applications the syringe needle
passageway 104 was contemplated as being located in the
rotor, offset from the axis of rotation thereof, and
accordingly rotation of the rotor moved the syringe
needle passageway making it difficult for automatic
means to align the syringe needle with the syringe
passageway in the valve.
U.S. patent 4,242,909 to Gundelfinger, a
later patent also assigned to Rheodyne Incorporated
does disclose in Figs. 7 and 8 thereof an automated
sampler-injector design utilizing the Bakalyar valve.
lO- t312480
1 However, as discussed earlier, such configuration only
allowed the entire contents of the overfill loop 18 to
be injected into the injector valve 156, and
- accordingly aliquot portions of the sampled quantity
were unable to be dispensed into the valve. Moreover,
such patent clearly disclosed on page Ç, lines 61-68
and page 7, lines 1-13 that the tube receiving passage
152 located in the rotor was to be rotated.
Accordingly, since the loop end 22 can only be inserted
into the loop end receiving passage 152 when such
passage is aligned with the liquid chromatograph column
14, should the column be under pressure, it is possible
leakage of the solvent from the column 14 could occur
from the loop-end receiving passage 152, and also
lS leakage of the sample contained in the overfill loop 22
from the loop end 22, up to the point in time the loop
end 22 is lowered into the loop-end passage 152 for
injection of the sample into the valve 156.
Accordingly, it is unclear from Gundelfinger precisely
how the Bakalyar valve is to function effectively
within the paramete~s of the design disclosed in
Gundelfinger.
t 3 1 2480
1 Summary of the Invention
In order to overcome the disadvantages
inherent in the prior art configurations for
automatically sampling and analyzing samples drawn from
sample containers, such as the problem of sample loss,
and further to be able to accurately and automatically
dispense multiple aliquots ranging in volume to as low
as one microliter from a single sampled quantity into
an injector valve for subsequent injection into a
liquid chromatograph column, the present invention
discloses both an automated sampler-injector apparatus,
as well as a method of sampling and analyzing, which
both achieve the above objects.
Accordingly, in one of its broad aspects, the
sampler-injector apparatus of the present invention
comprises a syringe means connected by tubing means to
an injector tube to form a syringe-loop, a carousel
means which holds and retains therein a plurality of
sample containers, means for positioning a selected one
of the sample containers immediately beneath the
injector tube, means for lowering the injector tube
into the selected sample container to withdraw a
quantity of sample therefrom, means for raising the
injector tube, means for positioning the carousel means
to allow the injector tube access to an injector valve
- 12 -
1312480
1 having a tube-receiving passage thereon, means for
positioning the injector tube in the tube-receiving
passage and operating the syringe to inject a portion
of the sampled quantity from the syringe-loop into the
injector valve and further into a sample loop connected
to the injector valve, means for switching the valve by
rotating one portion of the valve and keeping the other
portion of the valve containing the tube-receiving
passage stationary, to switch the sample loop from
being in fluid communication with the tube-receiving
passage to being connected at one end thereof to a
supply of pressurized solvent, and at the other end
thereof to a liquid chromatograph column, to thereby
allow the portion of the sample contained in the sample
loop to be flushed from the loop and injected intG the
liquid chromatograph column by the pressurized solvent
for analysis.
Accordingly, by providing a sampler-injector
apparatus of the above configuration, wherein the
syringe-loop may inject the portion of aliquot of the
sampled quantity directly into a sample loop for
subsequent transfer and injection at high pressure by
the injection valve into the liquid chromatograph
column, all "dead volume" within the tubing lines is
eliminated, since the syringe-loop by repetitively
~ 3 t 2480
1 injecting into the sample loop is able to transfer
essentially all of the sampled quantity and thus no
quantity of sample is unutilized.
Further, although injection valves of the
type contemplated for use in the present invention,
(i.e. having a tube-receiving passage) are kncwn for
manual uses, wherein the tube-receiving passage is
mounted on the rotor and extends parallel to but offset
from the axis of the rotor, and moves about such axis
when the rotor is rotated, (i.e. the valve is switched)
while the stator to which the supply of pressurized
solvent and the liquid chromatograph column are
connected remains stationary, by adapting such valve to
keep the portion of the valve containing the tube-
receiving passage stationary, and forcing the portion
of the valve to which the source of pressurized
solvent, and the liquid chromatograph column are
coupled to rotate, such valve is thus able to be
utilized in an automated sampler-injector.
Accordingly, the injector tube may now be placed within
the tube-receiving passage without fear that the
injector tube will be bent or broken-off when the valve
is switched, since the tube-receiving passage is now
held stationary, and the other portion of the valve is
rotated relative thereto, rather than ~he reverse, as
1312480
1 was taught in the prior art (ref. U.S. Patent 4,242,909
to Gundelfinger). Thus, all of the advantages of such
valve, such as those described in U.S. Patent 4,182,184
to Bakalyac, are now able to be realized. More
particularly, by utilizing a syringe loop and being
able to inject the portion of the sample into the
stationary tube-receiving passage of the valve at
atmospheric pressure, and subsequently switching the
valve to transfer the sample from the sample at high
pressure (up to 10,000 psi), a high pressure seal at
the injector tube - tube-receiving passage interface is
not now required. This differs from the Gundelfinger
configuration, which utilized an injector valve with a
tube-receiving passage, but which required a high
pressure seal at such location, because the overfill
loop was actually part of the sample loop, and was
accordingly subject to the pressurized solvent used for
flushing the sample into the liquid chromatograph.
In another of its broad aspects, the present
invention comprises a method for automatically sampling
a quantity of sample and injecting in consecutive
sequence portions of said quantity into a liquid
chromatograph column for analysis, from each of a
plurality of sample containers, comprising the steps
of: (a) positioning a carousel member containing a
- 15 -
1312480
1 plurality of sample containers so that a selected one
of the sample containers is disposed vertically beneath
an injector tube connected by tubing means to a syringe
means; (b) lowering said injector tube from an original
position into the selected sample container, and
operating said syringe means to draw up a quantity of
said sample through said injector tube into said tubing
means; (c) raising said injector tube to its original
position, and removing the selected sample container
from beneath said injector tube so as to expose a
multi-port injector valve vertically beneath said
injector tube; (d) switching said multi-port injector
valve so that one end of a sample loop, connected to a
first port on a second element of said valve, is
aligned and in communication with a tube-receiving
passage located in a first element of said valve; (e)
lowering said injector tube into said tube-receiving
passage (f) operating the syringe means to force a
portion of the quantity of sample contained in said
tubing means through said injector tube and into said
sample loop, said sample loop connected at its said
other end to a second port on said second element of
said valve; (g) rotating said second element of said
injector valve relative to said first element so that a
means for flushing said por~ion of sample from the
- 16 -
1312480
1 sample loop, connected to a third port on said valve,
is in fluid communication with one of said ends of said
sample loop, and a liquid chromatograph column
connected to a fourth port on said second element in
fluid communication with said other of said ends of
said sample loop, thereby flushing the sample from the
sample loop and into said chromatograph column; (h)
repeating the steps (d), (f) and (g) at least once; (i)
raising said injector tube to said original position;
and (j) positioning said carousel member so that a
further selected one of the sample containers is
disposed vertically beneath said injector tube.
Brief Descri~tion of the Drawings
Further objects and advantages will appear
from the following detailed description of the
invention, taken together with the accompanying
drawings in which:
Fig. 1 is a schematic view of a preferred
embodiment of the automated sampler-injector apparatus
of the present invention, showing the apparatus in the
sample position;
Fig. 2 is a schematic view of a preferred
embodiment of the automated sampler-injector apparatus
of the present invention, showing the apparatus in the
load-inject position;
1 31 248~
1 Fig. 3 is a view on arrow A of Fig. 2,
showing the rotatable carousel means of the preferred
embodiment of the present invention;
Fig. 4 is an exploded schematic view of the
injector valve used with ~he present invention in the
load position;
Fig. 5 is an exploded schematic view of the
injector valve used with the present invention in the
inject position; and
Fig. 6 is a cross-sectional view taken along
plane X-X of Fig. 4.
Detailed Description of the Invention
Figs. 1 and 2 show an automated sampler-
injector 10 of the present invention, having a carousel
means 12 for holding and retaining therein a plurality
of sample containers 14, each containing sample 16.
Syringe means 18 is provided, connected to tubing means
20 which is in turn connected to an injector tube 22 to
form a syringe-loop 24.
Means are further provided for positioning a
selected one of the sample containers 14 immediately
beneath the injector tube 22 to allow the injector tube
22 to be lowered into the sample container 14. In the
pref~rred embodiment the carousel means 12 is a
- 18 -
1312480
1 circular disc, and accordingly the means for
positioning the sample container is a motor means 26
capable of rotating the carousel means 12 so as to
position a desired sample container 14 beneath the
injector tube.
In the preferred embodiment, the circular
disc comprising the carousel means 12 has an axis of
rotation 13 perpendisular to the plane of the disc and
passing through its center 28, and further a plurality
of orifices 30 are provided on such carousel means
12. Such orifices 3n are aligned parallel to axis 13
and located along a common radii R about the periphery
of the disc, as shown in Fig. 3.
Raising and lowering means 32 are provided to
allow the injector tube 22 to be moved from an original
position (not shown) to a first position inside the
selected sample container 14 (see Fig. 1) and to a
second position inside a tube-receiving passage 34
located within a multi-port injector valve means 36
(see Figs. 2 and 6). The raising and lowering means 32
in the preferred embodiment consists of an electric
motor 38 having a rotatable toothed pinion ~ear 39
driving a toothed rack 40, but other means may be used
to cause raising and lowering of the injector tube 22.
-- 19 --
1312480
l Means for operating the syringe means 18 to
allow withdrawal of a quantity of sample 16 from the
sample containers 14 into the syringe-loop 24 may
similarly comprise an electric motor 42 having a
rotatable toothed pinion gear 44 driving a toothed rack
46 to which the syringe means 18 is affixed, but other
means may likewise be used to operate the syringe means
18.
Means for positioning the carousel means 12
to allow the injector tube 22 access to the tube-
receiving passage 3~ on the injector valve 36 are also
employed. In the preferred embodiment, wherein the
carousel means 12 is a circular disc, such means for
positioning entails utilizing the circular disc motor
means 26 to rotate an aperture 50 located in the
periphery of the disc and which passes in a straight
line through the thickness of the disc. Once the
aperture 50 is aligned immediately vertically below the
injector tube 22, the injector tube may be lowered and
inserted through the aperture 50, and into the tube-
receiving passage 34 on the injector valve 36. Other
means for allowing the injector tube access to the
injector valve 36 may be used, such as mechanical means
to either move the carousel means 12 away from the
injector tube 22 once a sample has been drawn up, or
- 20 -
1312480
1 means to move the injector tube 22 away from the
carousel 12 so as to allow the injector tube 22 free
access to the injector valve 36.
Means are further required to cause switching
of the injector valve 36 from a first load position
(Fig. 4), in which the tube-receiving passage 34 is in
fluid communication with one end of a sample loop 58 to
a second inject position (see Fig. 5), in which one end
of the sample loop 58 is connected through the injector
valve 36 to a high pressure solvent line 60 and the
other end thereof is connected through the injector
valve 36 to a liquid chromatograph column 62.
Accordingly, Figs. 1, 2, 4, 5 an 6 each show
a valve switching means 61,61' for carrying out the
valve switching. This switching means 61,61' may be
any number of mechanical or servo-mechanical means to
operate the valve 36 to cause switching of the valve.
In the preferred embodiment, the valve 36
which is contemplated as being used is comprised of a
first element or portion 66, which contains the tube-
receiving passage 34 which extends therethrough along a
straight line to a face 67 thereof. Such first element
66 is held stationary at location Y as shown in Figs. 1
and 2. A second element or portion 68 is adapted to be
rotated by said valve switching means 61,61' relative
- 21 - 1 3 1 2 4 8 0
1 to the first element 66, and has a face 69 axially
adjacent to and in bearing contact with the face 67 on
the first element 66. The second element 68 possesses
a first and second valve port 70 and 72 respectively,
to which the sample loop 58 is connected. The second
element 68 also possesses a third port 74 for
connection to a high pressure supply line 60 containing
solvent, and a fourth port 76 for connection to a
liquid chromatograph column 62.
A fifth port 78, which is used as a vent port
for discharging any unwanted contents of the sample
loop 58 during the load cycle, such as for example
displacing solvent remaining in such sample loop 58
from a recent cleaning cycle, is connected to a
discharge tube 80 which drains into a waste receptacle
32.
In operation, the sampling, loading, and
injecting steps using the automated sampler-injector
device 10 of the present invention are conducted as
follows.
Firstly, the carousel member 12 containing
the plurality of sample containers 14 is positioned so
that a selected one of the sample containers 14' is
disposed vertically beneath an injector tube 22
connected by tubing means 20 to a syringe means 18, to
~ - 22 - ~3t2480
1 form a syringe-loop 24, as shown in Fig. 1. Next, the
injector tube 22 at the end of the syringe-loop 24 is
lowered from an original position into the sample
container 14', and the motor 42 which operates the
syringe means 18 is activated to cause the syringe loop
24 to draw up from the sample container 14' a quantity
of sample 16 through the injector tube 22. The
injector tube 22 is then raised to its original
position, and the selected sample container is either
moved from its position beneath the injector tube 22,
or means are used to move the injector tube 22, so that
it has access to a multi-port injector valve 36.
As can be seen from Fig. 4, the valve 36 is
switched at this stage so that one end of a sample loop
lS 58, connected to a first port 70 on the second element
68 of the valve 36, is aligned and in fluid
communication with a tube-receiving passage 34 located
in the first element 66 of the valve 36. A solvent
pressure line 60 coupled to a third port 74 on the
second element 68 of the valve is in fluid
communication through the first element 66 of the valve
with a li~uid chromatograph column 62 coupled to a
fourth port 76 on the second element 68 of the valve~
The injector tube 22, once the valve is switched to
such load position~ is lowered by the raising and
- 23 - 1312480
1 lowering means 32 into the tube-receiving passage 34,
as shown in Fig. 2.
Accordingly, now that the valve 36 is in the
load position (see Fig. 4), the syringe means may be
S operated by activating the motor 42 thereof to thereby
force a portion of the quantity of sample 16 contained
in the syringe-loop 24 through the injector tube 22 and
into the tube-receiving passage 34 and sample loop
58. The sample loop 58 at its other end is connected
to a second port 72 on the second element 68 of the
valve, which is in fluid communication when the valve
is in the load position through the first element 66
with a fifth discharge port 78, as shown in Fig. 4.
The valve rotating means 61,61' are then
activated, once the sample loop 58 has been filled, to
rotate the second element 68 relative to the first
element 66 so that the high pressure solvent line 60
comes into fluid communication through the first
element 66 of the valve with one of ports 70,72 of the
sample loop 58, and the liquid chromatograph column 62
connected to the fourth port 76 on the second element
68 comes into fluid communication with the other of
said ports 70,72 of the sample loop 58, so that the
valve 3S is now in an inject position (see Fig. 5).
Accordingly, the high pressure solvent in line 60 is
~ - 24 -
1 3 1 2480
1 then allowed to flow to flush the portion of sample 16
in the supply loop 58 into the liquid chromatograph
column for analysls.
The volume of the sample loop 58 can be less
than the volume of the quantity of sample 16 drawn from
the sample contalner or, it may be greater. However,
pursuant to the invention it is necessary to at least
once more operate the valve switching means to switch
the valve back to the load position, operate the
syringe means 18 to dispense the sample into the sample
loop 58, and switch the valve back to the inject
position to again inject the new portion of sample into
the liquid chromatograph column 62. This process may
then be repeated until the quantity of sample in the
syringe loop 24 is exhausted. The advantage of the
above step is that an operator of the apparatus 10 is
now able to sequentially analyze portions of the same
quantity of sample. This increases the accuracy of the
liquid chromatograph results because of the averaging
effect from the number of runs.
After such steps, the injector tube 22 is
raised by the raising means 32 to its original
position, and the carousel means 12 is positioned so
that a further selected one of the sample containers
14' is disposed vertically beneath the injector tube
22. The process is then ready to be repeated.
- 25 - 1312480
1 In order to properly sequence the raising and
lowering motor 38, the syringe motor 42, the valve
rotating means 61,61', and the carousel positioning
means 26 to carry out the above method, a conteoller 90
may be used. Such controller may be a microprocessor
chip, printed circuit, or other such means to allow the
timely and proper se~uencing of operator of each of the
above components~
In order to eliminate the problem of
contamination of the injected portion of sample due to
remaining residual ~uantities of earlier samples
remaining within the sample loop 58 and injector valve
ports 70,72, a wash apparatus 100 may easily be
incorporated into the sampler-injector apparatus 10 of
the present invention. Accordingly, a wash reservoir
102 for containing a solvent may be provided, and a
pump means 104 further provided to force the solvent
through tubing means 106 into the syringe loop 24.
Valve means 108, optionally controlled by the
controller 9~, may be placed at the junction of the
tubing means 106 with the syringe loop, to allow flow
of solvent through the syringe loop 24 when the
injector tube 22 is in the tube-receiving passage 34,
and the injector valve 36 is in the load position, as
shown in Fig~ 2. This configuration allows the solvent
- 26 - 1312480
1 to purge the syringe loop 24, injector tube 22, valve
ports 70,72, and the sample loop 58 connected thereto,
of all previously remaining quantity of sample, prior
to withdrawing the injector tube 22 from the valve 36
and subsequently positioning another sample container
therebeneath. The flow of solvent through the above
components may then easily exit from the in~ector
valve through the fifth port 78 and into discharge tube
80 and thence into waste receptacle 82 (see Fig. 4) to
ready the apparatus 10 for sampling of another sample
quantity.
In the preferred embodiment, the wash
reservoir 102 is a sealed container, and the pump means
104 is an air pump connected to the wash reservoir to
pressurize the wash reservoir and thereby force solvent
contained therein into tubing means 106.
In order to utilize as much as possible all
sample quantity, in a preferred embodiment it is
contemplated that the tube receiving passage 34 located
within the first element 66 of the valve extend
straight through the first element 66 to the face 67
thereof which is in bearing contact with the face 69 of
the second element, as shown in Fig. 6. It is further
contemplated that the injector tube have a
substantially flat tip 95 lying in a plane
- 27 - 1312480
1 perpendicular to the axis of the injector tube 22, so
as to allow the injector tube 22 when inserted to the
full depth of the tube-receiving passage 34 to lie
flush against the face 69 of the second element 68, as
shown in Fig. 6. In this embodiment, however, the
first port 70 which in the load position is in
communication with the tube-receiving passage 34 and
injector tube 22 is contemplated as being narrower than
the injector tube 22 to prevent passage of the tube 22
into the first port 70. Accordingly, then, all of the
portion of sample forced into the injector valve 36 may
be transferred directly to the sample loop 58 through
the second element 68 of the valve 36, and may
subsequently be transferred to the liquid chromatograph
column 62 upon the valve being switched from the load
position (Fig. 4) to the inject position (Fig. 5) by
rotation of the second element 68 relative to the first
element 66.
Although the disclosure describes and
illustrates preferred embodiments of the invention, it
is to be undeestood that the invention is not limited
to ~hese particular embodiments. Many variations and
modifications will now occur to those skilled in the
art. For definition of the invention, reference is to
be made to the appended claims.
