U.S. patent application number 09/775958 was filed with the patent office on 2002-08-08 for fraction collector.
Invention is credited to Andersson, Lars.
Application Number | 20020104583 09/775958 |
Document ID | / |
Family ID | 25106053 |
Filed Date | 2002-08-08 |
United States Patent
Application |
20020104583 |
Kind Code |
A1 |
Andersson, Lars |
August 8, 2002 |
FRACTION COLLECTOR
Abstract
A fraction collector (1) for dispensing liquid from a liquid
source into receptacles (23) carried on a rotatable turntable (6),
wherein the turntable is connected to the fraction collector casing
(5) via a support arm (7) such that the turntable is rotatably
mounted at one end of said support arm, and said support arm at its
other end being rotatably mounted to the fraction collector casing.
Thereby it is possible to align any position of the turntable under
a dispensing tube (4) to dispense a liquid into a receptacle placed
anywhere on the turntable.
Inventors: |
Andersson, Lars; (Uppsala,
SE) |
Correspondence
Address: |
AMERSHAM BIOSCIENCES
PATENT DEPARTMENT
800 CENTENNIAL AVENUE
PISCATAWAY
NJ
08855
US
|
Family ID: |
25106053 |
Appl. No.: |
09/775958 |
Filed: |
February 2, 2001 |
Current U.S.
Class: |
141/145 |
Current CPC
Class: |
G01N 1/18 20130101; G01N
30/80 20130101 |
Class at
Publication: |
141/145 |
International
Class: |
B67C 003/00; B65B
043/42 |
Claims
What is claimed is:
1. A fraction collector (1) for dispensing liquid from a liquid
source into receptacles (25) carried on a turntable (6, 106) being
rotatable with respect to the fraction collector casing (5, 105),
comprising: the turntable (6, 106) connected to the fraction
collector casing (5, 105) via a support arm (7, 107) having two
ends, the turntable being rotatably mounted at one end of said
support arm, and said support arm at its other end being rotatably
mounted to the fraction collector casing.
2. The fraction collector of claim 1, wherein the fraction
collector further comprises a stepping motor (12, 112) for rotating
the turntable with respect to said support arm (7, 107).
3. The fraction collector of claim 2, wherein said stepping motor
(12) is mounted in said support arm (7).
4. The fraction collector of claim 2, wherein said stepping motor
(112) is mounted in the fraction collector casing (105), and
includes a belt drive which transfers the rotation of said stepping
motor to the turntable (106) via said support arm (107).
5. The fraction collector of claim 2, which further includes a
second stepping motor (13, 113) provided in the casing (5, 105) of
the fraction collector for rotating said support arm (7, 107) with
respect to the casing.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to fraction collectors, such
as fraction collectors used in the field of liquid
chromatography.
DESCRIPTION OF RELATED ART
[0002] Numerous fraction collectors including a rotatably mounted
turntable for supporting a plurality of collection tubes are known,
for example through U.S. Pat. No. 4,862,932. In fraction collectors
of the turntable type, a liquid is sequentially discharged into the
collection tubes through an outlet conduit, such as a hollow
needle. The outlet conduit is mounted on an arm reaching over the
turntable. Typically, the arm can swing around a vertical post to
be positioned over different radial rows of collecting tubes.
[0003] Similarly, fraction collectors wherein collecting tubes are
arranged in a rectangular grid pattern and an outlet conduit is
positioned over each collecting tube by a rectilinear positioning
movement are known. In such fraction collectors, herein referred to
as "X-Y-collectors", it is usually the outlet conduit that is moved
with respect to the collecting tubes. An example of such a fraction
collector is shown in U.S. Pat. No. 4,422,151.
[0004] An example of an X-Y-collector wherein both a receptacle
supporting table and a delivery head are moved linearly, in
transverse directions with respect to each other, is described in
U.S. Pat. No. 4,077,444.
[0005] In a conventional turntable fraction collector it is
possible to dispense liquid volumes into a selected number of
receptacles, for example test tubes. The dispensing means,
typically a metal or plastic tube extending from an arm reaching
over the receptacles, essentially is held at rest with respect to
the turntable, while the receptacles change place by rotating the
turntable when switching from one receiving receptacle to the
next.
[0006] The turntable fraction collector is useful in many
applications. However, in certain cases X-Y-collectors are more
suitable. For example, when handling a large number of receptacles,
bench space is more effectively used when arranging the receptacles
in a X-Y-pattern. There are also popular standardized receptacle
plates, so called microtiter plates, that have small recesses
arranged in a X-Y-pattern. Conventional turntable fraction
collectors cannot handle such plates.
[0007] A conventional X-Y-collector has a table for holding the
receptacles (or microtiter plates or similar), and is further
equipped with means for moving a dispensing tube over and between
the receptacles. Typically, the moving of the dispensing tube is
achieved by the use of a set of stepping motors. Furthermore, it is
known to control the stepping motors to position the dispensing
tube over any receptacle in any desired order.
[0008] However, compared to the turntable collector, a
X-Y-collector requires a longer attachment tubing, since the
equipment providing the liquid is stationary with respect to the
receptacles, and the tubing therefore has to follow the dispensing
tube to any receptacle. Especially in high-resolution liquid
chromatography this is a disadvantage since a long tubing give
separated components in the liquid longer time to diffuse within
the liquid flow, and consequently the precision of the separation
is negatively affected.
[0009] When switching from one receptacle to the next spillage
could occur due to an outflow through the dispensing tube between
the receptacles. Under certain conditions such spillage should be
avoided, for example when collecting fractions of a liquid holding
very valuable substances wherein it is important to collect each
individual drop. In such cases, a conventional X-Y-collector is
disadvantageous since the movement of the dispensing tube is apt to
shake off any drop developed at the end of the dispensing tube
during the switching movement.
[0010] The disadvantages of the conventional X-Y-collector, as
described above, could be overcome with a X-Y-collector wherein the
receptacle table is moved in the X and Y directions, instead of the
dispensing tube. However, with such a construction valuable
bench-space is lost.
SUMMARY OF THE INVENTION
[0011] It is the object of the present invention to provide a bench
space saving fraction collector with the ability to position a
selected receptacle among a plurality of receptacles, regardless of
the pattern in which the receptacles are arranged, under a
dispensing tube connected to a liquid feeding system
[0012] This object is achieved with a device of the type described
herein.
[0013] The fraction collector according to the invention combines
the features of the substantially resting outlet tube, short
attachment tubing length and small bench space requirement
connected with a turntable collector, with the features of
X-Y-arrangement ability and dispensing of liquid in a selectable
sequence of receptacles connected with a X-Y-collector.
[0014] Thus, the fraction collector of the invention is useful for
receptacles of any size (including of mutually different sizes)
arranged in any two-dimensional pattern, eg. in circular rows of
test tubes as well as microtiter plates.
[0015] Since the receptacles are moving during a receptacle change,
rather than the dispensing tube, the risk of losing drops is
reduced as compared to the conventional X-Y-collector.
[0016] As the dispensing tube is at rest with respect to the
receptacles it can be positioned very near the outlet of any liquid
feeding device, such as the outlet of a liquid chromatography
column, thereby providing for the shortest possible attachment
tubing.
[0017] All these advantageous features as well as others that are
obvious from the following detailed description of preferred
embodiments of the invention are obtained with a fraction collector
requiring a limited amount of bench-space.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a schematical perspective front view of an
embodiment of a fraction collector according to the present
invention.
[0019] FIG. 2 is a partly exploded rear view of the fraction
collector of FIG. 1.
[0020] FIG. 3 is an exploded view of a template arrangement for
placing a microtiter plate on the turntable of a fraction collector
according to the present invention.
[0021] FIG. 4 is a top view of a set of receptacles in a microtiter
plate, showing a system of coordinates associated with the
plate.
[0022] FIG. 5 is a top view of the plate according to FIG. 4
positioned on a turntable, showing a system of coordinates
associated with the shaft rotating the turntable.
[0023] FIG. 6 is a top view of a fraction collector according to
the invention, showing a system of coordinates associated with the
fraction collector casing.
[0024] FIG. 7 is a top view of the fraction collector according to
FIG. 6, after rotating the support arm.
[0025] FIG. 8 is a top view of the fraction collector according to
FIG. 7, after rotating the turntable.
[0026] FIG. 9 is a schematical side view showing a belt
transmission for use with an embodiment of the present
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0027] An embodiment of a fraction collector 1 according to the
present invention is shown in FIG. 1 and 2.
[0028] As is shown in FIG. 1, which is a perspective front view,
the fraction collector includes a dispensing assembly including an
extension arm 2 with a dispensing tube 4 mounted on a post 3, the
post being supported on a fraction collector casing 5. Receptacles
23 (represented with a schematical microtiter plate 23) are placed
on a turntable 6. The turntable is rotatably mounted on a support
arm 7. The support arm 7 is rotatably mounted on the casing 5 via a
supporting post 8. Connecting tubing and cables are not shown.
[0029] The arrangement is more clearly seen in FIG. 2, which is a
partly exploded rear view wherein the extension arm assembly for
reasons of clarity has been omitted and is symbolized by a hole 3A
for receiving the arm 3. The center of the turntable 6 is fixed
coupled to a first shaft 10.
[0030] The support arm 7 rotatably supports the first shaft 10 at
one end of the arm. A first stepping motor 12 is mounted in the
support arm 7, and is coupled to the first shaft 10. Thus, by
driving the first stepping motor 12 the first shaft 10 is rotated
and, in consequence, the turntable 6 is rotated therewith.
[0031] At its other end the support arm 7 is pivoted on the casing
5 via a tubular supporting post 8. A second shaft 14 extends
through the supporting post 8 to couple the extension arm 7 to a
second stepping motor 13 mounted in the casing 5. Thus, by driving
the second stepping motor 13 the second shaft 14 is rotated and, in
consequence, the support arm 7 is rotated therewith. As the support
arm 7 swings, the turntable 6 and its shaft 10 and motor 12 swings
therewith.
[0032] It should be noted that the detailed design of the
components of the fraction collector, their positions, how to mount
them in bearings etc. are not shown in detail. It is obvious for
anyone skilled in the art that numerous designs of the separate
components are possible, each one being well known in itself.
Therefore, the detailed designs should be selected to suit the
application at hand. This is also valid for the electric and
electronic driving circuits, since it is easy to control the
stepping motors (or any other suitable type of driving motors)
according to the invention once the invention is understood.
[0033] During operation the extension arm 2 is at rest and,
consequently, the dispensing tube is held still at a specific point
with respect to the casing 5.
[0034] The receptacles are arranged on the turntable 6 in any
selected pattern, but the position of each individual receptacle
with respect to the turntable should be registered and input to a
computer program for controlling the stepping motors 12, 13.
Typically, a number of arrangements are pre-selected, and the
corresponding receptacle positions are stored in a suitable
computer data memory, such as a RAM, to be loaded at the operator's
command. An easy way to arrange this is exemplified in FIG. 3,
wherein a template 22 (being selected from a plurality of templates
suited to different receptacle arrangements) has holes 28 that fit
onto pins 21 inserted in the turntable to be positioned at a
pre-selected position on the turntable. The template 22 has a
recess 24 that is formed to receive a specific model of a
microtiter plate 23 having a plurality of separate compartments 25.
As the pin positions, the recess position and the size and
positions of the compartments within the microtiter plate are
known, the position of each compartment 25 with respect to the
turntable 6 is easily determined in advance to be stored for use
with the computer program.
[0035] When selecting the length and direction of the extension arm
2, as well as the position of the post 3 in the casing 5, care
should be taken to ensure that the length of the arm 2 is enough to
allow the turntable to pass under the arm free from the post 3.
Furthermore, in order to ensure that all positions on the turntable
are reachable for the tube 4, provided that this is a requirement,
the tube should be positioned such that the first shaft 10 could be
placed right below the tube.
[0036] According to the invention, by selecting the lengths of the
extension arm 2, the support arm 7 and the turntable 6 radius for
cooperation as described above, any position at the turntable can
be positioned below the dispensing tube by suitably rotating the
support arm 7 around the supporting post 8 while suitably rotating
the turntable 6 with respect to the support arm 7.
[0037] This shall now be explained in more detail with reference to
FIGS. 4-7, and using a small (non-standard) microtiter plate having
four times three recessed compartments for receiving liquid. Such a
plate 23 is shown in a top view in FIG. 4. Any compartment can be
identified by its x-y-index, as defined in FIG. 4. As an example to
be used throughout this explanation, the right uppermost (when
viewing FIG. 4) compartment has the index x=4, y=3, and will
therefore be referred to below as the (4, 3)-compartment. The
compartments are separated in the x-direction with a distance D,
and in the y-direction with the same distance D.
[0038] A receptacle system of coordinates with its origin of
coordinates in the center of the microtiter plate is defined by a
receptacle x-axis 35 coinciding with the direction of the rows of
compartments in the microtiter plate and a receptacle y-axis 36
extending perpendicularly with respect to the x-axis 35, as shown
in FIG. 4. It is easily recognized that the x,y-position of the
center of the exemplary (4, 3)-compartment with respect to the
receptacle system of coordinates is (1.5*D, D).
[0039] The position can also be expressed in polar coordinates as
(r*cos(.beta.o), r*sin(.beta.o)), wherein
r=(Lx.sup.2+Ly.sup.2).sup.1/2an- d .beta.o=arc cos (Lx/r).
[0040] Thus, the polar coordinates for the (4, 3)-compartment with
respect to the receptacle system of coordinates is
((3.25).sup.1/2*D*cos(.beta.o)- , (3.25).sup.1/2*D*sin(.beta.o),
wherein .beta.=arc cos (1,5/(3.25).sup.1/2).
[0041] The microtiter plate 23 is positioned at the turntable 6 in
such a way that the center of the microtiter plate, or more
generally the origin of coordinates for the receptacle system of
coordinates, coincides with an imagined extension of the central
axis of the first shaft 10, as shown in FIG. 5. It is preferred to
use a template, as described above, to ensure a correct
positioning.
[0042] A turntable shaft system of coordinates, as shown in FIG. 5,
with its origin of coordinates coinciding with a point at the
extended central axis of the first shaft 10 is defined by a
turntable x-axis 31 and a turntable y-axis 33 perpendicular with
respect to the x-axis 31.
[0043] Furthermore, according to FIG. 6 a casing system of
coordinates with its origin of coordinates coinciding with a point
at the central axis of the second shaft 14 is defined by a casing
x-axis 32 and a casing y-axis 34 perpendicular with respect to the
casing x-axis 32.
[0044] The casing system of coordinates is fixed with respect to
the casing 5. The origin of the turntable shaft system of
coordinates follows the first shaft 10, but each axis is always
parallel to the corresponding axis of the casing system of
coordinates. That is, the turntable x-axis 31 is always parallel
with the casing x-axis 32, although the origin of coordinates of
the turntable shaft system of coordinates is moveable with respect
to the casing system of coordinates.
[0045] A start position for the fraction collector according to the
present embodiment of the invention is shown in FIG. 6. The
center-to-center distance between the first and second shafts 10
and 14 is R.sub.ARM. In the start position, the arm 7 is positioned
at an angle .beta.o with respect to the casing reference x-line 32.
Similarly, in the start position the receptacle x-axis 35 (not
being shown in FIG. 6) coincides with the turntable x-axis and is
therefore parallel with the casing x-axis 32.
[0046] Thus, the start position of the center of the (4,
3)-compartment with respect to the casing system of coordinates
is
(R.sub.ARM*cos(.alpha.o)+(3.25).sup.1/2*D*cos(.beta.o),
R.sub.ARM*sin(.alpha.o)+(3.25).sup.1/2*D*sin(.beta.o))
[0047] FIG. 7 shows a position after that the arm 7 has been
rotated around the second shaft 14 an angle .alpha. with respect to
the casing system of coordinates, to be positioned at a new angle
.alpha.1 with respect to the casing system of coordinates
(.alpha.1=.alpha.o+.alpha.). During the movement of the arm 7, the
first axis 10 has been held at rest with respect to the support arm
7. Therefore, the receptacle system of coordinates will no longer
coincide with the turntable shaft system of coordinates, but will
be rotated with respect to the turntable shaft system by the same
angle .alpha. that the arm 7 has been rotated.
[0048] If, in addition thereto, the first shaft 10 is rotated an
angle .alpha. with respect to the support arm 7, the receptacle
system of coordinates is also rotated the angle .alpha. with
respect to the turntable system of coordinates and, consequently,
also with respect to the casing system of coordinates. This is
shown in FIG. 8. In summary, the receptacle system of coordinates
is now at an angle of .beta.1=(.beta.o+.alpha.+.beta.) with respect
to the casing system
[0049] Therefore, after rotating the first shaft 10 to the angle
.alpha.1, with respect to the casing system of coordinate, and the
second shaft the angle .beta.1 with respect to the support arm, the
center of the (4, 3)-compartment is now at the point
(R.sub.ARM*cos(.alpha.1)+(3.25).sup.1/- 2*D*cos(.beta.1),
R.sub.ARM*sin(.alpha.1)+(3.25).sup.1/2*D*sin(.beta.1)) with respect
to the casing system of coordinates
[0050] Thus, starting from a first position for a separate
receptacle, the receptacle can be positioned anywhere within an
annular area surrounding the second shaft 14, the annular area
having an inner radius of (R.sub.ARM-r) and an outer radius of
(R.sub.ARM+r), provided that no obstacles are placed within the
area. This means that in the case that the dispensing tube 4 is
positioned anywhere on the circle representing the radius R.sub.ARM
around the second shaft 14, it is possible to align any receptacle
on the turntable under the tube 4.
[0051] The receptacles could be arranged according to any pattern
on the turntable, as long as their initial positions with respect
to the turntable are known, and a computer program used for
controlling the operation of the fraction collector is updated with
the present positions. For example, more than one microtiter plate
could be placed on the turntable.
[0052] In operation, a computer program can be used to control the
rotation of the first and second shafts via a control unit. Since
anyone skilled in the art is able to design a control unit and a
suitable computer program to suit a certain embodiment of a
fraction collector according to the invention, this will not be
described in detail.
[0053] However, for each receptacle to be filled, and in any
selected order, the turntable is rotated to place the receptacle
under the dispensing tube. Accordingly, the position of the
dispensing tube 4 (X.sub.DT, Y.sub.DT) with respect to the casing
system of coordinates has to be known and input to the controlling
computer program.
[0054] A second embodiment of the present invention, as shown
schematically in FIG. 9, differs from the first embodiment in that
the motor 112 rotating the turntable 106 is mounted within the
casing 105, instead of being mounted in the support arm 107. With
this arrangement the support arm is relieved from the weight of the
motor, and no electrical wires need to be guided through the
support arm.
[0055] The rotation of the turntable driving motor 112 is
transferred to the turntable 106 via a first belt 120 running
around a first belt pulley 121 attached to the first shaft 110 of
the turntable and a second belt pulley 122 attached to a drive
shaft 123 being driven by the turntable driving stepping motor
112.
[0056] The first shaft 110 is mounted in a bearing (not shown) in
the free end of the support arm 107, while the drive shaft 123 runs
through a tubular post 108 fixedly attached to the support arm 107
and mounted in bearings (not shown) in the casing.
[0057] A second belt 124, that runs around a belt groove 126 in the
tubular post 108 and a belt pulley 125 attached to the drive shaft
of a second stepping motor 113, the second motor being mounted
within the casing 105, transfers the rotation of the second motor
to the tubular post, thereby rotating the support arm.
[0058] It should be noted that the illustration of the second
embodiment, as shown in FIG. 9, is schematical in that no details
of the attaching means are shown. It is of course obvious for
anyone skilled in the art that the components that form the second
embodiment could be formed and assembled in numerous ways, each one
selected to suit the application at hand.
[0059] Of course, the rotating movement could be transferred to the
turntable by any suitable means other than a belt transmission,
such as a chain transmission, a gear transmission or a universal
drive shaft.
[0060] In addition to the advantages described above for a fraction
collector according to the present invention even more advantages
could be obtained. For example, minimal band broadening related to
the separation of fractions within the outlet tubing before the
dispensing means is achievable due to the short tubing. The
non-moving dispensing tube support makes it possible to attach a
detector, such as an UV detector at a favorable position near the
dispensing means. Furthermore, faster tube shifting is possible
since no drops are lost due to dispensing means movement.
[0061] It is obvious for anyone skilled in the art that many
variations of the invention are possible within the scope of the
invention. Such variations include, but are not limited to, the
type of driving means for the shafts (such as DC motors with gear
boxes), the position of the motors (such as mounting a stepping
motor in the turntable, or mounting both motors in the support
arm), using one stepping motor only to drive both the turntable and
the support arm, providing the dispensing tube in a separate stand
free from the fraction collector etc. The specific embodiments
described are given by way of example only, and the invention is
limited only by the terms of the appended claims.
* * * * *