GB2456130A

GB2456130A - Preparation of specimens

Info

Publication number: GB2456130A
Application number: GB0725141A
Authority: GB
Inventors: Mark Edward Fish; Melvyn Whiteside
Original assignee: RTS Life Science Ltd
Current assignee: Azenta UK Ltd
Priority date: 2007-12-24
Filing date: 2007-12-24
Publication date: 2009-07-08
Anticipated expiration: 2027-12-24
Also published as: GB2456130B; GB0725141D0

Abstract

A sample preparation apparatus (100) for processing a sample arranged in a sample tube together with a solvent, the apparatus comprising: a homogenizer (300), operable to agitate the sample tube and so assist the sample to dissolve in the solvent; a centrifuge (400), operable to separate insoluble materials from a desired solution; and a robotic system (110) arranged to transport a sample tube holder (220), e.g. a rack, or a carrier, comprising the sample tube (230), between the homogenizer and the centrifuge, and wherein the sample tube holder is arranged to be securely attachable to, and detachable from, the homogenizer and the centrifuge.

Description

IMPROVEMENTS IN AND RELTING TO THE PREPARATION OF

SPECIMENS

The present invention relates to the processing of specimens, particularly pharmaceutical or biological specimens, so that various tests and procedures can be performed thereon.

In particular, but not exclusively, the present invention is concerned with the homogenisation of a pharmaceutical preparation and its subsequent separation into soluble and insoluble components, by action of a centrifuge.

In studies of pharmaceutical compounds, it is important to test the quantity of active component included in a

particular preparation (pill or tablet). Prior art

techniques involved dissolving one or more such doses in a suitable solvent system such as acidified water with the optional addition of an organic co-solvent such as methanol, ethanol or acetonitrile and then removing any insoluble components (excipient and the like) before analysing the remaining solution, which should include substantially all the active ingredient.

Typically, following sample preparation, analysis via high performance liquid chromatography or UV/visible spectroscopy is required in order to ensure that the dosage is correct and uniform across the batch being sampled.

There are various prior art techniques used to ensure that a sample has substantially completely dissolved in the solvent. Some involve stirrer baths or ultrasonic methods to aid the process, but a common approach typically used in automated apparatus a mechanical homogenisation process where the sample for analysis is added to the solvent and mechanically homogenised by action of a rotating blade which is immersed into the mixture. The rotation blade smashes the sample into fragments, the soluble parts of which are then dissolved into the liquid solvent. The insoluble parts are suspended in the solution. The process of homogenisation can take a significant time, especially in the case of certain forms of slow-release pharmaceuticals which are specifically formulated to break down and dissolve over a prolonged period of time. A typical cycle time can be in the region of 20-30 minutes using such an apparatus. Once the homogenisation is complete, the insoluble compounds must be removed and this is typically performed by filtration. The filtration process uses a disposable filter cartridge which removes the insoluble portion and allows the wanted solution to pass through.

A disadvantage of the mechanical prior art system

described is the time taken to prepare the wanted solution. When a large batch of samples is tested, the total time required can be excessive or can require a large number of test stations operating in parallel to achieve the required throughput.

Another disadvantage is the possibility of contamination from the rotating blade structure, the pipes used in the filtration system or from the filter cartridge itself.

Furthermore, the quantity of solvent required can be more than ideal in order to allow a sufficient volume of liquid for the blades to adequately operate and, subsequently, to ensure that components of the system are cleaned between operating cycles.

An aim of an embodiment of the present invention is to address the disadvantages in the prior art, whether mentioned herein explicitly or not.

According to the present invention there is provided an apparatus and method as set forth in the appended claims.

Other features of the invention will be apparent from the dependent claims, and the description which follows.

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which: Figure 1 shows a sectional plan view of an embodiment of the invention; Figure 2 shows a sectional side view of an embodiment of the invention; Figure 3 shows a sample caddy forming part of an embodiment of the invention; Figure 4a shows a view of an homogeniser suitable for use in an embodiment of the invention; Figure 4b shows an adaptation made to the homogeniser of Figure 4a, which forms an embodiment of the invention; Figures 5a and 5b show a locking pin in an unlocked condition; and Figures 6a and 6b show a locking pin in a locked condition.

An embodiment 100 of the present invention is shown in Figures 1 and 2. The device comprises three main sections: a staging area 200 for housing samples to be processed; an homogeniser 300; and a centrifuge 400. Positioned above these three sections and communicating with each of them is a gantry robotic system 110, 120 arranged to move samples between the sections.

The staging area 200 comprises a turntable 210 which is configured to hold a plurality of sample caddies 220, with each caddy being arranged to hold a plurality of individual sample tubes 230.

The staging area 200 is arranged behind a safety-interlocked door 130 and allows new samples for processing to be introduced to the system and for processed samples to be removed for analysis.

Each sample is added to a sample tube 230, which is a simple container having a screw-cap for securely closing the tube and preventing spillage. Once the sample and solvent have been added to the tube, the tube is placed in a caddy 220 as shown in Figure 3. Each tube also includes a grinding matrix, which can comprise a plurality of ceramic beads, or similar, which, when vibrated vigorously with the samples, cause homogenisation to occur. The grinding matrix does not affect the active ingredient under analysis and is itself unaffected by the homogenisation process.

Each caddy 220 can accommodate a plurality of tubes, and the example shown has five tubes. The number of tubes per caddy may vary in different embodiments.

Once a caddy is filled with tubes, it can be placed on a support on the turntable. From here, it can be moved to the homogeniser section 300 by use of the robot 120.

The robot 120 travels along a track 110 which runs above all three sections of the device. When instructed to do so, it travels to the staging area 200, picks up the caddy 220 in the defined position, as determined by its position on the turntable 210, and transports it to the adjacent homogeniser section 300 where it is placed on the homogeniser.

The homogeniser 300 is a device which produces very rapid oscillations of the sample caddy 220, causing the solid samples to collide violently with each other and the grinding matrix, thereby causing them to break up and dissolve in the solvent. The homogeniser is controlled by a central controller running a control programme and is active for a defined time, which is selected based upon the type of sample being processed. As noted, certain slow-release formulations will require a longer processing time than regular formulations.

The homogeniser 300 can be any suitable device which creates a suitable vigorous and rapid oscillatory action.

It has been found that the device described in US Patent 5,567,050 provides the desired level of performance. A brief overview of its operation is included herein to aid understanding of the invention, but the skilled person will realise that other devices and configurations can achieve the same or similar effects. The configuration shown in Figure 4a is subtly different to that used in a preferred embodiment of the invention, but the principle of operation is best explained using this figure. Figure 4b shows an adaptation, suitable for use with an embodiment of the invention.

Figure 4a shows a close-up detailed view of the active part 10 of homogeniser 300. The apparatus 10 comprises a drive motor 12 having a vertically oriented output or drive shaft 14 which is rotatable about a fixed vertical axis, the motor being hung or suspended from anchor structure shown generally at 18, the motor being capable of rotating at speeds up to at least about 8000 R.P.M. The anchor structure 18 includes a plate 21 and blocks 7 on which it is set, the blocks in turn being mounted on drum 6. Intervening the plate 21 and the blocks 7 is a resilient material pad 20 which preferably is of rubber and one which exhibits stiffness in respect of a twisting thereof yet is readily flexible and yielding in respect of vertical force applied thereto. Pad 20 serves to damp vibrations transmitted through the plate 21 that otherwise could enter the drum 6 and transmit to the casing C. The apparatus includes oscillatory motion producing means shown generally at 22, said means including an eccentric mounting collar 11 integral with a hub 13, this unit being screwed on to shaft 14 and rotatable with shaft 14.

This oscillatory motion producing means also includes a bearing unit comprised of an inner race 21 clamped between hub 13 and a nut 15 threaded on shaft 14 so as to be fixed to rotate with the mounting collar, an outer race 23 fixed to a central bore of a relatively widened, relatively shallow vessel holder 24 made preferably in the shape of a disc located a distance above the anchor structure, and a plurality of ball bearings 19 captive between the races. A preferred form of bearing is a double row angular contour ball bearing.

The mounting collar 11 has an outer surface which is symmetrical about an axis K which is skewed longitudinally of the fixed shaft axis F. Thus it is seen that the vessel holder 24 is mounted on the mounting collar such that vessel holder vessel receptive structure is symmetrically arrayed with respect to this skewed axis K. Further it is seen that relative rotatability exists between the vessel holder and the mounting collar.

With this arrangement, it is seen that if the vessel holder 24 not be held during rotation of the mounting collar 11, the vessel holder would be caused to have a certain rotation in unison with the mounting collar about axis K, such rotation being at the inclined solid line showing of the vessel holder in FIG. 2. On the other hand, if the vessel holder 24 is haltered or held during mounting collar 11 rotation, the vessel holder will be caused to oscillate vertically up and down and symmetrically with respect of fixed axis F. This movement is illustrated in exemplary showing in dashed line vessel holder fragment positioning as at OS in FIG. 2.

A halter means is used to prevent rotation of the disc 24 in unison with the mounting collar 11 during apparatus operation. This halter means can be, e.g., a tension type coil spring 36 connected to the disc at an underface part thereof and with the anchor structure 18, connection to the anchor structure minimizing extraneous vibration transmission to the spring. The spring 36 will be connected to the underf ace of the disc 24 at a radial location thereon which is closely proximal the shaft 14 and such that the spring disposes parallel to fixed axis F, this being done to limit the degree of tensing produced in the spring thereby reducing fatigue effect and lengthening spring useful service life.

By haltering the disc 24, oscillatory motion producing means drive effect thereon is as mentioned above to rapidly vertically oscillate the disc, periphery of the disc ring describing an imaginary rolling wave course about the shaft 14, it being understood that there is no circular travel of the shaft during oscillation thereof.

The result is that the vials 26 are rapidly oscillated in vertical reciprocal movements at a rate of as much as eight thousand oscillations per minute (133 Hz). Due to that rapid oscillatory movement of the vial, average linear acceleration values of up to 415 g are produced in the vial contents.

Figure 4b shows a slight adaptation to the device shown in Figure 4a, which allows the automatic connection of the sample caddy 220 to the homogeniser 300, by use of the robot 120. In the apparatus of Figure 4b, which shows part of homogeniser 300, there is added a shaft 302, with which the sample caddy is arranged to engage, as described shortly.

In order to allow easy connection of the sample caddy 230 to shaft 302, it is preferable to ensure that shaft 302 is substantially vertical. However, the arrangement of the homogeniser means that the shaft is offset from the vertical as shown. There are two straightforward possible solutions to this problem. The first is to mount the homogeniser 300 on an inclined support, thereby ensuring that the shaft 302 is substantially vertical at all times.

The second approach is to mount the homogeniser 300 on a tiltable platform, such that the entire homogeniser is tilted when the caddy 230 is attached or detached, such that the shaft 302 is substantially vertical at those times.

Once the caddy 220 has been transferred to the homogeniser 300, it must be securely locked in position to ensure that it remains in situ throughout the homogenisation process, which can exert forces in excess of 2000N on the caddy.

Once the caddy 220 has been located on the homogeniser by the robot, a locking pin 240 is used to secure it in place. The locking pin 240 is integrally formed with or permanently attached to the caddy 220. The locking pin 240, shown in isolation in Figures 5a and 6a, is designed to be easily operable by the robot 120. It comprises a lower, relatively narrow, shaft 242 arranged to pass through the lower portion of the caddy 220 and engage with the drive shaft 302 of the homogeniser and an upper, relatively wide, shaft 244 arranged to be accessible from the upper surface of the caddy and to be grasped by the robot's gripping mechanism 122. At the upper surface of the locking pin is a button 246, the depression of which causes the locking mechanism to be deactivated. The locking mechanism comprises a plurality of ball bearings 248, which are retained within the lower shaft 242, but allowed to protrude through a plurality of suitable dimensioned apertures. When the button 246 is depressed, an internal member causes the ball bearings 248 to travel into the shaft so as not to protrude. When the button is released, the internal member forces the ball bearings 248 to protrude through the apertures and to engage with suitable positioned recesses in the rotor or drive shaft 302 of the homogeniser, as shown in Figure 6b, thus securely locking the caddy in position. The button is biased towards the locked state and so the lock must be specifically deactivated to release the caddy 220.

To pick up a caddy 220 and couple it to the homogeniser 300, the robot 120 is provided with a gripping mechanism 122 which grips the upper shaft 244 of the locking pin 240 and so picks up the associated caddy from the turntable 210 in the staging area 200.

Then, a plunger descends from the robot's gripping mechanism 122 to depress the button 246, thus withdrawing the ball bearings 248. The robot lowers the caddy into position, such that the lower part 242 of the pin 240 engages with the drive shaft 302 of the homogeniser. The plunger is withdrawn, causing the locking mechanism to engage as described. The robot can then withdraw from the homogeniser, leaving the caddy securely locked in position by the locking pin 240.

With the caddy 220 firmly secured in position, the homogeniser 300 can be started, according to a predefined programme. The homogeniser rapidly and vigorously vibrates the caddy containing the samples for as long as is specified in the controlling programme. At the end of the operation, which may be in the region of ten seconds to five minutes, the homogeniser stops and the caddy may be removed by the robot and taken to the final stage.

In order to unlock the locking pin 240 and remove the caddy 220, the process is effectively the same as that already described in reverse.

The next step in the process is to process the sample such that the solution for analysis is easily separable from the insoluble excipient and grinding matrix which is also present in the tube 230. Prior art techniques employed filtration, but embodiments of the present invention employ a centrifuge 400 to cause all the insoluble materials to be forced into the bottom of the tube 230, thus allowing the solution of interest to be easily drawn off in a later operation.

The robot 120 picks up the caddy 220 by the locking pin 240 and transports it to the centrifuge 400, where it is placed in position and locked in place using the same locking technique as previously described. Advantageously, the rotor of the centrifuge 400 and that of the homogeniser 300 are adapted to use the same locking pin 240 to secure the caddy in position, allowing the robot to easily move the caddy 220 between the two machines and secure it in place.

Once securely locked in position, the centrifuge is activated for a defined time, typically in the range 4 -minutes, according to the controlling programme. A suitable centrifuge for this application has a speed of 6000 RPM or greater and is capable of imparting a relative centrifugal force (RCF) in the range of 3500g -4500g to the tubes loaded in the rotor. Suitable centrifuge devices are manufactured by Hermle LaborTechnik under the model numbers Z300 and Z323 although other manufacturers produce suitable devices and the skilled person will be aware of

suitable devices.

Once the centrifuge 400 has completed its process, the robot unlocks the locking pin, in the same way as described previously, and then retrieves the caddy and transports it back to the staging area, from where it can be collected by a user for the final analysis step, which is carried out elsewhere.

The entire operation of the device is controlled by means of a touch panel control 140 accessible from the exterior of the device, and used to control a suitably programmed microcomputer or similar processor arrangement. The touch panel control 140 allows the various operational parameters to be set individually or for one or more pre-defined programmes to be used.

Embodiments of the invention have been described herein in relation to preparing a pharmaceutical or chemical sample f or further analysis. However, embodiments of the invention can also be used for a variety of other purposes including cell-lysing applications and other similar biological sample preparation processes.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features

disclosed in this specification (including any

accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. Sample preparation apparatus for processing a sample arranged in a sample tube together with a solvent, the apparatus comprising: an homogeniser, operable to agitate the sample tube and so assist the sample to dissolve in the solvent; a centrifuge, operable to separate insoluble materials from a desired solution; and a robot arranged to transport a caddy comprising the sample tube between the homogeniser and the centrifuge, and wherein said caddy is arranged to be securely attachable to, and detachable from, said homogeniser and said centrifuge.

2. Apparatus as claimed in claim 1 wherein the robot is positioned above both the homogeniser and the centrifuge and comprises a gripper operable to descend and pick up the caddy.

3. Apparatus as claimed in claim 1 or 2 wherein the apparatus further comprises a staging area for housing a plurality of sample caddies.

4. Apparatus as claimed in claim 3 wherein the staging area comprises a turntable.

5. Apparatus as claimed in any preceding claim wherein the caddy is securely attachable to the homogeniser and the centrifuge by means of a locking pin.

6. Apparatus as claimed in claim 5 wherein the locking pin is integrally formed with the caddy.

7. Apparatus as claimed in claim 5 or 6 wherein the robot comprises means to unlock the locking pin.

8. Apparatus as claimed in claim 7 wherein the means to unlock the locking pin is a plunger operable to depress a push-button on the locking pin.

9. A method of preparing a sample comprising the step of providing a robotic system to transfer a sample caddy between a homogeniser and a centrifuge, wherein said robotic system is adapted to securely lock and unlock the sample caddy to/from the homogeniser and/or the centrifuge.

10. A method of preparing a sample for analysis, comprising the steps of: using a robot to pick up a sample caddy comprising the sample; using the robot to transport the sample caddy to an homogeniser; using the robot to locking the sample caddy into position; operating the homogeniser; using the robot to unlock the sample caddy; using the robot to transport the sample caddy to a centrifuge; and operating the centrifuge.

11. A method as claimed in claim 10 further comprising the step of using the robot to unlock the sample caddy from the homogeniser and transporting the sample caddy to a staging area.

12. Apparatus as hereinbefore described, having particular reference to the accompanying figures.

13. A method as hereinbefore described, having particular reference to the accompanying figures.