WO2008032030A2

WO2008032030A2 - Improvements in and relating to the storage and delivery of liquids

Info

Publication number: WO2008032030A2
Application number: PCT/GB2007/003402
Authority: WO
Inventors: Mark John Frogley; Yildiz Uludag; Marion Rehak; Christopher John Hammond; Sia Brahami
Original assignee: Akubio Limited
Priority date: 2006-09-12
Filing date: 2007-09-10
Publication date: 2008-03-20
Also published as: WO2008032030A3; GB0617923D0

Abstract

A sealed container (4) provides a reservoir of reagent, buffer solution or other liquid for a scientific laboratory or diagnostic instrument or medical device. The liquid in the sealed container is in a degassed state and the container is flexible so as to be at least partially collapsible, thereby to inhibit the aeration of the liquid remaining in the container after the latter has been opened and some of the liquid removed. The container, or a cap (8), for use therewith may include a tapered portion to assist in the expulsion of any residual gas from the container. The container and liquid may form part of a liquid delivery system further comprising a supply conduit (2) and a connector (5) for releasably connecting the container to the supply conduit (2).

Description

1266.01/ A

Title: Improvements in and Relating to the Storage and Delivery of Liquids

Field of the Invention

This invention relates to a sealed container of liquid, in particular a reagent or buffer solution, and to a liquid delivery system for a scientific, laboratory or diagnostic instrument or medical device.

Background to the Invention

It is becoming increasingly common to connect a scientific, laboratory or diagnostic instrument to a reservoir of buffer solution or other liquid reagent used in volume which is consumed over the course of a period in which the instrument is performing successive tests. Examples of such instruments are High Performance Liquid Chromatography (HPLC) and Fast Protein Liquid Chromatography (FPLC) apparatus, cell culture delivery systems, capillary flow instruments, anaerobic fermentation and analytical instruments for example Quartz Crystal Resonance or Surface Plasmon Resonance biosensor instruments. This approach may also be applicable to any scientific or diagnostic instrument or medical device where provision of reagents or other fluids is important.

In the example of Quartz Crystal Resonance or Surface Plasmon Resonance biosensor systems, the buffer solution, conventionally based on a phosphate buffer solution or Hepes (or HPS: N-(2-hydroxyetheyl) piperazine-N'-(2-ethanesulfonic acid); 4-(2-hydrozyethyl)-l- piperazineethanesulfonic acid), is used to prime and wash biosensing surfaces, to establish conditions for the detachment of affinity bound molecules and for the measurement of kinetic parameters in an assay or experimental programme. In such programmes, selective variation of the conditions of pH and ionic strength of the running buffer is often used. The buffer solution from the reservoir can also be used as a "running buffer" which steadily flows through the instrument's fluidic system and over the sensor surface when the latter is not being exposed to reagents to be immobilised or analytes to be captured for example.

It is potentially important that the buffer supplied to the instrument is particle free, sterile and substantially free of dissolved gas. Dissolved gas can have a detrimental effect on the performance of the instrument because in many cases the dissolved gas may coalesce into small or microscopic bubbles which cause artefacts in the collected data, particularly in devices where the sensor located in the flow cell is sensitive to changes in density or refractive index of the fluid above the sensor, such as in quartz crystal resonance sensing or surface plasmon resonance. Such bubbles can cause shifts or drift in the sensor signals, rendering the data unusable.

Various means such as signal processing have been used in an attempt to overcome this problem, but the provision of gas free buffer to the sensor surface remains the most effective way to avoid the problems. Generally, therefore, users must prepare and degas their own buffer solutions, which is a time consuming process. One supplier does currently provide pre-prepared buffer solutions in Tetra packs (RTM), but to use these the user needs to make an incision or cut in the corner of the pack and insert a tube through which buffer solution is then withdrawn under pumping action by computer controlled pumps in the instrument.

To avoid re-aeration of this solution during shipping, transport and storage, the pack is filled with negligible headspace, but once opened immediately allows its contents to come into contact with air through the cut opening. ,

As the re-aeration rate of bulk liquid is proportional to the area of the air-liquid interface and is enhanced by agitation, pump extraction of the solution from such a pack reaerates the buffer and causes a reduction in the useful post-opening lifetime of the supply of buffer solution. As a result, typical useful lifetime of such packs is only 1-2 days. In addition, there is a risk that air could be drawn into the instrument as the last of the buffer solution is removed from the pack. To avoid this, it is common for users to discard packs after only some of the buffer solution therein has been used.

Summary of the Invention

According to a first aspect of the invention, there is provided a sealed container of liquid wherein the liquid is in a degassed state and the container is flexible so as to be at least partially collapsible, thereby to inhibit the aeration of the liquid remaining in the container after the latter has been opened and some of the liquid removed.

Accordingly, as liquid is removed from the container, the latter can partially collapse, without rupturing, so as to inhibit or prevent the ingress of air.

Preferably, the container is at least partially collapsible to the extent that the removal of a volume of degassed liquid from the container causes a corresponding reduction in the container's internal volume, if no other fluid is allowed to enter the container.

Thus the collapse of the container can substantially prevent the creation of headspace in the container.

The degassed liquid has application in analytical chemical devices, such as chromatographic, and biosensing devices

Preferably, the degassed liquid comprises a buffer solution and/or a solution for washing or priming biosensing devices and/or a solution for detaching affinity bound molecules from a sensing surface.

Alternatively the degassed liquid may be de-ionised water The concentration of dissolved air, as opposed to dissolved oxygen in the solution depends on the degassing conditions, particularly the temperature. Following degassing under a set of standard conditions the concentration of oxygen is a good indicator of the concentration of dissolved air. As dissolved oxygen is easier to measure accurately at low levels than dissolved air, this is the preferred metric for dissolved air.

Preferably, the concentration of dissolved air and oxygen in the solution is reduced to a level equal to that found by evacuation of a volume of approximately 20 litres for 20 minutes at 0.2 bar at a temperature of 45 degrees Celsius.

Preferably, the concentration of dissolved oxygen in the solution is 6ppm or less.

Preferably, the concentration of dissolved oxygen in the solution is between 4 and 5ppm.

In fact the lower the better as it extends shelf life, so more preferable is between 2 and 4ppm, and most preferably less than 2ppm (These numbers can be achieved depending on the setup and type of the degassing rig).

Preferably the liquid is sterile

The container may to advantage comprise a flexible pouch, which is capable of being substantially fully collapsed without rupturing the container walls.

Thus the enclosed volume within the container may be substantially zero when the container is empty thereby to enable substantially all of the liquid to be discharged without being aerated within the container.

The pouch may conveniently be formed from one or more sheets of a plastics laminate material and preferably of a laminate comprising a metalised plastic layer or other coated plastic sheet having a low permeability to gases. Other coated plastics laminates having low gas permeability may be suitable.

Preferably, there is substantially no headspace in the container, but the volume of liquid is less than the maximum volume of the container.

This can be achieved by, for example, squeezing or otherwise deforming the container prior to sealing. Consequently, the risk of spillage of liquid during the opening of the container is reduced and there is an expansion volume in the sealed container to accommodate the increase in volume of the contents if the container is kept in freezing conditions during storage or transportation.

The container may to advantage have an internally tapered portion at its outlet, so arranged as to facilitate the expulsion of gas from the container when the outlet is held uppermost.

Thus any residual gas in the sealed container or any gas entering the container on opening the latter will tend to collect at the top of the taper and hence at the outlet so that substantially all of said gas can then be flushed out with some of the liquid by squeezing the container.

The tapered portion and/or outlet may to advantage be included in an initially separate cap, attachable to the container after the latter has been opened.

The full container may be sealed with a screw threaded shipping cap, which is subsequently replaced with the cap having the outlet and/or tapered portion when liquid is to be dispensed from the container.

There is preferably also provided a connector for releasably connecting the container to a liquid supply conduit for supplying liquid to an instrument, the connector preferably including a valve which is open when the connector is connected to the conduit but is closed by disconnecting the connector from the conduit. Alternatively, the container may include an outlet valve which is opened by attaching a cap to the container.

The connector may conveniently be included in a cap for the container.

Users frequently require samples of the buffer for calibration and possibly dilution of sample material, and, with known containment arrangements, the extraction of such samples may introduce turbulence in the packs and thus lead to re-aeration. Additionally, the extraction of samples results in the repeated removal and reinsertion of the tube through which the liquid is extracted in conventional arrangements. Consequently, that tube needs to be regularly cleaned. By contrast, the connector with the valve enables the instrument supply conduit readily to be detached from the container and, since the conduit does not need to be inserted into the container, does not need to be repeatedly cleaned. A second conduit may be provided for connection to the cap via the outlet to carry expelled liquid and air to a waste receptacle or to extract a sample by squeezing the pouch.

Furthermore, this feature also enables a partially emptied container to be disconnected without aerating the liquid remaining in the container so that the remaining liquid is available for subsequent use. Accordingly, the useful lifetime of the contents of the container is increased.

Preferably, the container includes sealing means for sealing the outlet of the container prior to use and a cap attachable to the container so as to break said seal to allow the contents of the container to be expelled through the cap.

Preferably, the sealing means comprises a barrier, the cap preferably having a piercing member for breaking the seal by rupturing the barrier.

The piercing member may to advantage comprise a needle. Preferably, the barrier comprises a septum.

The septum is preferably rubber.

If the piercing member is provided on the cap, the latter preferably includes a sealing collar which surrounds the piercing member, and is arranged to abut and seal against a surface of the container, other than the cap, to seal the interior of the cap against the rest of the container before the seal is ruptured.

According to a second aspect of the invention, there is provided a liquid delivery system for a scientific instrument, the system comprising a container and liquid in accordance with the first aspect of the invention, a supply conduit for conveying liquid from the container to the instrument and a connector for releasably connecting the container to the supply conduit.

The conduit may, for example, comprise a tube.

Preferably, the apparatus includes a valve for sealing the container when the latter is disconnected from the conduit. The valve may be a non-return valve to prevent the return of fluids from one section of the conduit contaminating the fluid in the other section on reconnection.

The system may to advantage include a further connector, attached to the conduit, which is releasably attachable to the first said connector to connect the container to the conduit. The further connector including a valve for preventing liquid exiting, or air entering the conduit while the two connectors are disconnected from each other.

According to a third aspect of the invention, there is provided a container containing a degassed buffer solution for an instrument, the container including an internally tapered portion which leads to an outlet for the container, the arrangement being such that, when the container is orientated with its outlet uppermost, the tapered portion will guide any gas in the container to the outlet for expulsion therethrough. The outlet and tapered portion may be included in an initially separate cap attachable to the container after the latter has been opened. Alternatively the tapered portion may be a part of the container separate from any cap.

The container may further be used to supply an instrument which comprises an on-board degassing unit, to improve the performance or the final level of dissolved gas obtained by the degassing unit over that achieved when the liquid or other buffer supplied to it is not degassed.

Brief Description of the Drawings

The invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a diagrammatic view of a liquid delivery system in accordance with the invention, including a pouch also in accordance with the invention;

Figure 2 is an isometric view of the pouch, showing the pouch when sealed with a shipping cap;

Figure 3 is an isometric view of apparatus for use in filling pouches, such as the pouch of Figure 2, three at a time.

Figure 4 is a partially sectioned side view of a cap for the pouch;

Figure 5 is a sectional side view of a connector on said cap and a co-operating connector on the end of a tube for conveying liquid from the pouch the two connectors being shown disconnected from each other; Figure 6 is a similar view, showing the two connectors connected together;

Figure 7 is an isometric view, corresponding to Figure 3, of another type of apparatus for use in filling three of the pouches at a time;

Figure 8 is a sectional side view of an alternative embodiment of cap on the neck of a pouch which has been sealed by a rubber septum;

Figures 9a and 9b are sectional side views of the upper portion and cap of a further embodiment of pouch, in which a valve is provided in the neck of the pouch;

Figure 9c shows the underside of the portion shown in Figures 9a and 9b, both of which are sections taken along the line A-A of Figure 9c;

Figures 10 and 11 illustrate alternative approaches to filling pouches, Figure 10 showing a pouch being filled from underneath and Figure 11 showing a pouch being filled from the side.

Detailed Description

The system shown in Figure 1 is operable to supply a buffer solution to a scientific instrument, 1 in the present example a quartz crystal resonance or surface plasmon resonance biosensor instrument through a conduit in the form of a connection tube 2. The instrument is provided with an onboard pump for drawing the buffer solution along the tube 2 from a reservoir contained in a pouch 4. The buffer solution is used, in a known way, in the instrument, for example to prime or wash the biosensor surfaces of the instrument (e.g the surfaces of the quartz crystal wafers which carry an immobilised coating, in the case of a quartz crystal resonance instrument), and also for detaching affinity bound molecules, and maintaining the instrument in 'idle' mode following the completion of an assay or experimental programme. De-ionised water can be used to purge the instrument following cleaning of the instrument to remove all traces of cleaning reagents, and to leave the instrument idle over extended periods when the use of salt containing buffers might risk build up of deposits in the instrument.

The end of the tube 2 remote from the instrument 1 is attached to a first connector 5 which releasably, matingly engages a complementary connector 6 on a cap 8 screwed onto a screw threaded a translucent neck 22 of the pouch 4. The system is also provided with a sampling tube 10, one end of which is terminated at a connector 12 similar to the connector 5. The connector 12 can also matingly engage the connector 6 so that a sample of liquid can be extracted from the pouch 4 via the tube 10. In addition, the connector 12 and tube 10 can provide an outlet for any air initially in the pouch 4 (in the way discussed below).

With reference to Figure 2, the pouch 4 is formed from a pair of opposed sheets of laminated material. One layer of the laminate comprises a metallic coating, and a second layer of the laminate is a heat sealable layer. The sheets are heat-sealed together along two opposed longitudinal seams 14 and 16 to define the container walls. The top and bottom of the pouch are defined by corresponding gusset-like spacer portions, each of which is heat sealed to the two sheets. In Figure 2, the top spacer portion is denoted by reference numeral 18, whilst the one of said opposed sheets to which it is heat sealed is denoted by reference numeral 20. The bottom spacer portion is formed of the same laminated material as the walls. The top spacer is in this case a moulded plastic insert which also comprises the neck 22. A shipping cap 24 is attached to the neck 22 and closes the pouch 4.

The sheet material for the pouch 4 is chosen to have suitable gas permeation properties. To that end, the pouch may, for example, be of the kind supplied by Nalgene such as its clear plastic 500ml pouch CAT 332902-0500 or 1.5L pouch CAT number 332902-1500, and 332900 and 342900 wide mouthed pouch product lines.

The present example, as mentioned above, uses a metalised foil laminate and may therefore be, for example, a Pactech 21819 pouch. All of the above types of pouches are sufficiently rigid not to collapse under their own weight when filled thus facilitating handling and shipping. The lower spacer portions in the pouches open under the weight of the liquid and form a flat surface to enable the pouches to stand upright on a horizontal support surface. Pouch sizes of up to 3 litres with this property are available. The pouch material can be chosen to have a degree of flexibility such that, when connected to the instrument pump, in a closed system, the action of the pump can withdraw liquid and cause the pouch to collapse. It has been found that, under such conditions, such pouches are capable of collapsing to almost zero volume, thus allowing maximum extraction of liquid.

The shipping cap 24 is formed from plastics material and provides an air tight seal against the neck 22 under standard closure torques.

The pouch 4 is filled with a degassed buffer solution made up in a conventional way, either from raw material powder ingredients or from concentrates supplied by, for example, Sigma, Hyclone or SAFC Biosciences. The solution can then be degassed using a variety of commercial degassing systems suitable for the volumes chosen. In that connection, the SOTAX Media Preparation Station can produce solutions of approximately 20 litres in volume with dissolved oxygen levels of around five parts per million. Smaller volumes (in the region of 8 litres) may be produced by the Dosaprep X8 Media Preparation Station. Larger volumes may be produced by known types of membrane based process equipment.

Using the SOTAX Station it was determined that degassing of HBS buffer at 40 degs C and 0.2 bar for 30 minutes resulted in Dissolved Oxygen levels of typically 3.7ppm. Similar results were obtained for Milli-Q water and PBS buffer.

In order to prevent air being incorporated into the buffer as a result of turbulence arising during the filling operation, degassing apparatus such as the SOTAX apparatus mentioned above may be programmed to expel a predefined volume of buffer solution into the pouch. The apparatus may also impose a filling regime whereby the flow rate during the initial filling stages is low, increases during filling and then decreases again as the programmed volume is approached. At the start of the filling process, the filling tube on the degassing apparatus (not shown) is placed with its end in the bottom of the pouch 4. As the pouch 4 fills, the filling tube is raised to maintain its position just below the liquid surface, and is then lifted gently clear of the surface when the pouch is full. It is possible to overset the fill volume by a small amount to take account of variation in manufactured pouch volumes. The programmed volume can be determined experimentally in order to achieve those ends.

In the absence of a preprogrammed volume facility in the dispenser, the pouch can be filled to a predetermined weight.

Once the pouch has been filled in this way, a slight pressure is applied to the pouch during the application of the shipping cap 24 to expel any air that has been included in the pouch contents during the filling process. This squeezing can be achieved using the apparatus shown in Figure 3.

The apparatus comprises a metal housing having two opposed side plates 30 and 32 separated by a rear plate 34, and which support an upper metal strip 36 which has three lined openings 38, 40, 42 each for receiving the neck of a respective pouch. Thus, for example, the pouch 4 is shown in position in the apparatus with its neck in the opening 38. A lower strip 44 extends across the bottom edge of the apparatus from the plate 30 to plate 32 and carries three hinged fingers 46, 48 and 50, which are rotatable about the same horizontal axis.

A bar 52 extends behind the fingers 46, 48 and 50 and is held in position in vertical slots 54 and 56 each in a respective one of the plates 30 and 32. The bar has screw threaded ends and is frictionally held in position at a selected height in the slots 54 and 56 by end nut and washer arrangements, such as is shown at 58.

In use, each pouch in the apparatus is squeezed by pressing the respective hinged finger against the pouch until the finger abuts the bar 52. Thus the bar 52 ensures that all the pouches are compressed by the same amount. It will also be appreciated that the position of the bar 52 can be adjusted to vary the amount of expelled liquid, by being moved vertically in the slots 54 and 56. With the pouches so squeezed, the caps for shipping are applied and tightened to standard torque settings. Alternatively the pouches may be squeezed during filling. The thread profile and sealing mechanism of the shipping caps and the necks of the pouches is chosen to provide a suitable liquid and airtight seal, and are the same as that used in the instrument cap. A peripheral annular cavity the same as that shown as 68 in Fig 4 seals around the rim of the neck which is profiled to mate against the bevelled inner edge of the cavity when the cap is screwed onto the neck of the pouch with a specified torque. For example, the American Petroleum Institute semi buttress thread 35.5dia-6 T.P.I, may be used to secure the seal.

An improved device 220 for filling is shown in Fig 7, in which control of the headspace volume is improved, thus enabling headspace volume to be minimised and so reduce the amount of gas redissolved in the liquid. The station is shown with three pouches 231 232 233 in place. Pouch 233 is being filled via the dispensing tube 230 of the degassing unit.

Pouch 232 is in the process of having the level of liquid adjusted to ensure minimum headspace, and pouch 231 is sealed with the shipping cap. The fingers of the device shown in Fig 3 are replaced by a circular pad 220 rotatably mounted on a shaft 223 which is in turn attached to rotary knob 221. The shaft 223 is screw threaded and engages a bracket 224 which is mounted on rails 225, to enable it to slide along the row of containers to bring the pad into register with any selected one of the containers. The filling station is equipped with a level detector 226 which can be translated along rails 222 to position it over the open neck 227 of pouch 232. The pouches are mounted in substantially the same way as in the apparatus shown in Figure 3. To fill a pouch to near zero headspace, it is first filled with a defined volume of liquid. The defined volume should be sufficient to substantially fill the pouch, but leave a headspace in the top of the pouch. The level detector 226 is moved to be above the open neck and the knob rotated which causes the pad to contact and squeeze the pouch and raise the internal liquid level in the pouch. The level detector comprises an ultrasonic proximity sensor, (type 458 5533 available from RS components) 228 which is directed towards the liquid surface. The detector 228 can be calibrated to detect when the liquid rising through plastic neck, reaches a warning level, at which stage a warning LED 229 positioned above the open neck lights to inform the operator. The warning level can be set to be an appropriate level below the rim of the neck, typically 1-3 mm. The operator then carefully applies the shipping cap. A light source 233 positioned behind the neck illuminates the translucent neck for assistance. By this means the final headspace can be well controlled, and headspace air volumes of below 1 ml achieved . It can be seen that such a process could be automated by incorporating electronic control of the pad displacement linked to the level detector signals, and by feeding filled packs though the station.

When a pouch has been filled in this way, the volume of the liquid contained in the pouch will be less than the maximum capacity of the pouch, but (because the pouch was compressed) there will nevertheless be substantially no headspace in the pouch. This reduces the risk of spillage during the subsequent opening of the pouch, and also provides an expansion volume in the pouch in the event of freezing conditions during transportation or storage.

A very small air volume included will dissolve in the degassed liquid. Although this elevates the gas level this has been found to make a negligible difference on the level of dissolved gas and is normally acceptable. Table 1 shows the effect of leaving a small headspace below the rim of the neck of the pouch. A batch of 500 ml pouches were made and filled as described above, using the apparatus of Fig 3. Dissolved Oxygen levels were measured immediately after filling, and after storage at room temperature 1 week later.

ϊo. Dissolved O₂ (ppm) Notes

Initial Final average

1 3.72 5.1 l-2mm

2 3.72 5.45 5.31 air-gap

3 3.72 5.37

4 3.72 5.56 5mm

5 3.72 5.62 5.62 air-gap

6 3.72 5.69

7 3.72 6.27 10mm

8 3.72 6.03 6.12 air-gap

9 3.72 6.07

It can be seen that the dissolved O₂ level increases as the greater volumes of headspace gas become dissolved in the solution.

Provided the pouch material is chosen appropriately, such a sealing process provides a solution which will keep dissolved oxygen/air at an acceptable level. Alternatively, it is possible to seal a less permeable pouch in a higher barrier wrapper under vacuum to provide additional protection. At these levels the formation of bubbles in the instrument is prevented.

It has been found that under appropriate cleaning regimes of the degassing equipment, combined with the sterile filtration, the sterility of the liquid in the pouch may be maintained. The Sotax degasser was sterilised using 0.1M HCl solution by running one cycle at the end of use, and then left in this condition until the next operation. Similarly, the nozzle was sterilised by storage in 0.01M HCl solution. After sterilising the system was purged and 4 1500ml pouches were filled with HBS buffer solution using a sterile filter incorporated into the filling station nozzle 230 (Watman. Polycap 0.22micron TC filter). 4 pouches were filled, and 2 pouches were stored at room temperature and 2 pouches at 37°C for 5 weeks, following which they were tested for bacterial growth and found to be sterile. In practice the incorporation of the filter in the nozzle has been found to increase the dissolved oxygen content by about 0.5ppm.

Liquids may also be sterilised in bulk by gamma irradiation or alternatively the entire process may be carried out under sterile conditions.

When the pouch is to be connected to the rest of the liquid delivery system, the shipping cap is removed, and replaced with the cap 8, which is shown in more detail in Figure 4. The cap 8 comprises a cylindrical body 60 of a plastic material, having a coaxial opening 62 which extends up from the underside of the cap, and has a screw threaded lower half 64 which engages the neck of the pouch 4. At the top of the portion 64 there is provided an annular recess 66 in the side of the opening 6 which aids in the machining of the screw thread in the cap. The top of the opening 62 includes a peripheral annular cavity 68 which seals against the top of the neck of the pouch as described above. The cavity surrounds an inverted funnel shaped recess 70 which also extends from the top of the opening 62, and thus defines a tapered portion in the cap 8. The top of the recess 70 is connected via an L-shaped passage 72 to the connector 6 which is screwed into a screw threaded radial bore in the cap 8. To that end the connector 6 includes an integral flat faced portion 74 which can be engaged by a tool, such as a spanner, to facilitate tightening of the connector 6 into the radial bore. The funnel shaped recess 70 accommodates at least some of the liquid which might be inadvertently expelled from the pouch during the attachment of the cap 8.

The inboard end of the connector 6 bears against a washer 76 which in turn clamps a circular filter 78 in position in the path of flow from the pouch 4 to the connector 6. The filter 78 can prevent any solids in suspension in the liquid in the pouch 4 entering the tube 2.

With reference to Figure 5, the inboard end of the connector 6 has an inlet opening 80, which is concentric with the connector and leads to an axial passage 82 which accommodates a compression spring 84 at the end of the connector opposite opening 80. The passage 82 is of a larger diameter than the opening 80, so that there is provided a shoulder 86, surrounding the opening 80. The compression spring 86 acts between that shoulder and a valve barrel 88 that is axially slideable in a sleeve 85 and extends beyond both ends of the sleeve. The barrel has, at its inboard end, a flange 90 against one side of which the spring 84 acts. An annular groove on the other side of the flange 90 locates an O- ring seal 92 that is urged against a valve seat defined by a tapered portion of the passage 82. The portion of the barrel 88 in which the flange 90 and seal 92 are provided is solid so that liquid is prevented from flowing through the passage 82 when the seal 92 is urged against the seat 94. However, the other end of the barrel is open, and the barrel includes radial openings such as opening 96, through which liquid may enter the barrel (from the upstream portion of passage 82) when the seal 94 is unseated. The sleeve 85 includes two external annular grooves, one of which accommodates an O-ring seal 98 adjacent the downstream end of the passage 82, the other, groove 100, accepting a locking plate 102 on the connector 5. The plate 102 is biased in an upward direction by a spring (not shown) and includes an aperture that passes over the sleeve 85 so that said spring urges the plate 102 into the groove 100 to secure the connectors 5 and 6 together. The plate can be released by pushing, against the action of the spring, an integral finger 104 which extends perpendicularly to the rest of the plate.

The seal 98 acts against the inner wall of a passage 106 in the connector 5 to prevent the escape of liquid being transferred from connector 6 to connector 5. A step in the passage 106 defines an annular shoulder against which compression spring 108 acts, thereby to urge a barrel 110 (slideably mounted in passage 106) to the right as viewed in Figure 5. The end of the barrel 110 closer to the plate 102 is open and leads to a hollow portion 111 in which radial openings such as at 112 are provided. The opposite end of the barrel 110 is closed and carries an O-ring seal 114 which is urged against a seat, in the form of a tapered portion 116 in the passage 106, with the barrel so sealed, liquid is prevented from travelling along the connector 5.

The connecting together of the connectors 5 and 6, as shown in Figure 6, results in the outboard end of the barrels 88 engaging the open end of the barrel 110 so that the barrels displace each other, against the action of the springs 86 and 108 to unseat the seals 95 and 116. This allows liquid to flow into the passage 82, into the radial openings in the barrel 88, out of the open, outboard end of the barrel 88, into the open end 111 of barrel 110, through the radial openings in the latter and then into tube 2 from the downstream end of passage 106. However, when the connectors are disconnected, the flow of liquid is prevented.

The connector 12 is identical to the connector 5.

The connectors disclosed here are either of the type PCMD180428121, and PMCD480428121, available from Colder Products Inc., or are modified variations thereof. When the pouch is to be first used, connector 12 is connected to the connector 6, and the pouch squeezed, to expel any gases (which will have accumulated at the top of the tapered portion 70). The connector 12 can then be removed and the connector 5 attached. Since connectors 5 and 6 both include shut-off valves, the pouch 4 can be disconnected, for example to enable a sample of liquid to be obtained through connector 12 and tube 10 for calibration purposes, without allowing air into either tube 2 or the pouch 4.

The invention enables pouches of different fluids to be serially connected used and disconnected with minimum air ingression and cross contamination, extending shelf life and improving usability of the instrument.

Further enhancements may be incorporated into the instrument to control the use of packs, for example if the pump stroke is known, software may be used to count the pump strokes, and monitor usage. An alarm can be provided when the pumped volume exceeds a percentage of the pouch volume. Pouches may be bar coded or comprise a smart chip and be individually read by the instrument to determine the original volume, buffer nature, pouch identity, date of manufacture etc. A user may enter the date of first opening, expelled volume during calibration analysis etc. Using this data the instrument can keep records of the amount remaining in each pouch identity, and estimate the lifetime available based on manufacturer's data. Preferably where instruments allow users to construct assays, the required volume of buffer may be calculated from the assay protocol. This enables the instrument to advise the user on whether an individual pouch identity has sufficient volume for completion of the experimental programme.

Figure 8 shows an alternative type of cap 151 attached to the neck 152 of a pouch identical the pouch shown in Figures 1 and 2 except for the fact that the pouch of Figure 8 includes a membrane seal 153 in the form of a rubber septum stretched over the top of the neck 152 and sealed around its periphery to the neck. The cap 151 is hollow and includes a central upper aperture 160 through which a needle 150 extends. The needle 150 is fixed to the cap 151 at the aperture and is attached at its upper end to a solution delivery tube (not shown).

The needle 150 extends vertically into the cap and into an axial passage of an annular rubberised collar 154, the needle being a snug slideable fit within the axial passage. The collar 154 is attached to a spring 157 which is, in turn, attached to the internal surface of the top of the cap. This exerts a downward biasing force on the collar 154, but also allows the collar 154 to rotate relative to the cap 151, the collar 154 being slideable relative to the needle 150.

In use, the cap 151 is screwed onto the neck 152, causing the collar first to make contact with the top of the neck on which the septum 153 is provided. The spring urges the collar 154 against the septum to make a seal around the periphery of the latter. As the cap 151 is screwed further on to the neck 152, the spring 157 compresses and the needle 150 slides downwards through the collar to puncture the septum 153. When the cap is unscrewed, the needle is withdrawn from the septum, which, because it is rubber, will re-seal. Capillary action inside the needle will ensure that the solution in the needle and the delivery tube is retained, which limits the amount of air that is introduced into the solution pathway on connection of the cap to the container.

It will be appreciated that, as the cap 151 is screwed on to or unscrewed from the neck 152, the collar 154 remains stationary against the septum 153, so that the needle 150 and cap 151 rotate and slide relative to the collar 154.

Alternately the septum may be manufactured from a material that forms a seal around the needle but does not reseal when the needle is withdrawn. Such materials are suitable for a a single use pouch which is not removed from the instrument until the contents are consumed by the instrument. In this example, the pouch is filled to the top of the neck leaving only a small volume of air present under the septum 153. The septum 153 can be heat sealed to the rim of the neck 152. As the solution is extracted from the pouch, the latter collapses, and the seal between the collar 154 and septum 153 prevents the ingress of air, thus allowing the contents of the pouch to be maintained substantially at their initial dissolved air content.

Figures 9a-c show an arrangement in which a resealable shut off valve is incorporated into the neck 202 of a pouch, and is so arranged that the action of attaching a cap onto the pouch directly opens the valve within the neck of the pouch and allows fluid to pass through a passageway into the connecting tube. Fig 9a shows the neck valve in the closed configuration, with the cap detached. A solid insert 211 in the top of the pouch is welded to the neck 202 and constitutes the top of the pouch. The insert 211 has a tapered portion, in the form of a shallow conical inner surface, which is used to assist the accumulation of residual air under the neck 202. The neck comprises a cavity 208, within which barrel 210 sits. The barrel has two cruciform end parts 205, 209, which allow it to slide within cylindrical apertures at each end of the cavity. In the closed configuration the bevelled surface 204 seals against O-ring 203, under the action of spring 207, and the upper cruciform section 209 protrudes above the inner surface 212 of the neck.

Fig 9b shows the neck valve in the open configuration, with the cap attached. The cap comprises a second barrel 201 integrally formed with the screw thread and pipe stub 206. On screwing the cap onto the neck, the second barrel pushes against the outer edges of the cruciform section 209, and displaces the barrel in the neck against the spring, breaking the contact of the bevelled surface with the O-ring. The cruciform sections allow liquid to be pumped from the pouch via the channels between the arms of the lower cruciform section into the cavity 208, and then via the channels between the arms of the upper cruciform section into the pipe 206, and onwards into the instrument.

With such an arrangement the user can be provided with a second cap connected to a sample tube for the purposes of taking samples and removing residual air. Figures 10 and 11 illustrate alternative approaches to filling a pouch in such a way as to leave the pouch with near zero headspace. Both approaches involve filling the pouch through a region other than the neck (which has already been sealed with a septum) before the pouch has been fully formed. In both cases, the pouch material is a laminate and is such that two pieces of the material can be heat sealed together by sandwiching those two pieces between a pair of heated, opposed jaws.

In Figure 10, the pouch has an upper gusset like portion 171 from which a neck extends, and to which two opposed sheets of laminate material are heat sealed. The two sheets are also heat sealed together along two side seams 170 to define the sides of the pouch. A pair of opposed heated jaws (one of which is shown at 174) heat seal the sheets together along a bottom seam to define the underside of the container. However, before this happens, the container is filled through its bottom 173 by means of a dispensing tube 172 which is inserted into the container whilst the latter is held in an inverted position. The container is filled with liquid to a level just above the tops of the jaws, and the sheets are then sealed together by the jaws below the liquid level 175 (after the dispensing tube 172 has been withdrawn). The excess laminate material above the upper edges of the jaws (such as the edge 176 of jaw 174) is cut off and discarded.

In the alternative type of form filled container shown in Figure 11, the pouch has an upper insert 305 (incorporating the neck) and a lower insert 306 which respectively constitute the top and bottom of the pouch. With the pouch held in the orientation shown in Figure 11 (on its side), the heat seals between the sheets and the inserts 305 and 306 extend vertically from a lower horizontal seam 304. The sheets 301 and 302 are also sealed together in regions above each upper extremity of the inserts 305 and 306 to provide sealed walls in the region 307 and 308. Thus, three sides of the pouch have already been formed.

Before the fourth side is formed, the pouch is filled via the opening 311, using dispensing tube 303, opposite the previously sealed side seam 304 to greater than the required volume such that the fluid level 310 extends above the line at which the areas 307 and 308 meet the inserts 305 and 306. The filling tube is then withdrawn and the opening is sealed by heat sealing jaws, one of which is shown at 309, again through the liquid level. The seal thus formed is twice the necessary width measured in the direction across the finished pouch so that it can be cut to form the finished pouch and the remaining sealed width constitutes the first side seal (corresponding to seal 304) of the next pouch.

Claims

1. A sealed container of liquid wherein the liquid is in a degassed state and the container is flexible so as to be at least partially collapsible, thereby to inhibit the aeration of the liquid remaining in the container after the latter has been opened and some of the liquid removed.

2. A sealed container according to claim 1, in which the container is at least partially collapsible to the extent that the removal of a volume of degassed liquid from the container causes a corresponding reduction in the container's internal volume, if no other fluid is allowed to enter the container.

3. A sealed container according to claim 1 or claim 2, in which the degassed liquid comprises a liquid for use in a chemical or biochemical analytical instrument.

4. A sealed container according to any of the preceding claims, in which the degassed liquid comprises a buffer solution and/or solution for washing or priming biosensing devices and/or a solution for detaching affinity bound molecules from a sensing surface.

5. A sealed container according to any of the claims 1 to 3, in which the liquid is de-ionised water.

5. A sealed container according to any of the preceding claims, in which the concentration of dissolved oxygen in the liquid is 6ppm or less.

7. A sealed container according to claim 6, in which the concentration of dissolved oxygen in the solution is between 4 and 5ppm.

S. A sealed container according to claim 6, in which the concentration of dissolved oxygen is between 2 and 4ppm. ). A sealed container according to claim 6, in which the concentration of dissolved oxygen is less than 2ppm.

10. A sealed container according to any of the preceding claims, in which the liquid is sterile.

11. A sealed container according to any of the preceding claims, in which the container comprises a flexible pouch, which is capable of being substantially fully collapsed without rupturing the container walls.

12. A sealed container according to claim 11, in which the pouch is formed from one or more sheets of plastics laminate material.

13. A sealed container according to claim 12 in which the laminate comprises a metalised plastic layer or other coated plastic sheet having a low permeability to gases.

14. A sealed container according to any of the preceding claims, in which there is substantially no headspace in the container, but the volume of liquid is less than the maximum volume of the container.

15. A sealed container according to any of the preceding claims, in which the container has an internally tapered portion at its outlet, so arranged as to facilitate the expulsion of gas from the container when the outlet is held uppermost.

16. A sealed container according to claim 13, in which the tapered portion and outlet are included in an initially separate cap, attachable to the container after the latter has been opened.

17. A container according to any of the preceding claims, wherein there is also provided a connector for releasably connecting the container to a liquid supply conduit for supplying liquid to an instrument, the connector preferably including a valve which is open when the connector is connected to the conduit but is closed by disconnecting the connector from the conduit.

8. A container according to claim 17, in which the connector is included in a cap for the container.

9. A container according to any of the preceding claims, wherein the container includes an outlet valve which is opened by attaching a cap to the container.

0. A container according to claim 19 in which the valve is located in a neck of the container.

1. A container according to any of the preceding claims, in which the container includes sealing means for sealing the outlet of the container prior to use and a cap attachable to the container so as to break said seal to allow the contents of the container to be expelled through the cap.

2. A container according to claim 21 , which the sealing means comprises a membrane, the cap having a piercing member for breaking the seal by rupturing the membrane.

3. A container according to claim 22, in which the piercing member comprises a needle.

4. A container according to claim 22 or claim 23, in which the membrane comprises a rubber septum.

.5. A container according to any of claims 22-24, in which the cap includes a sealing collar which surrounds the piercing member, and is arranged to abut and seal against a surface of the container, other than the cap, to seal the interior of the cap against the rest of the container before the seal is ruptured.

6. A liquid delivery system for a scientific instrument the system comprising a container and liquid in accordance with any of the preceding claims, a supply conduit for conveying liquid from the container to the instrument and a connector for releasably connecting the container to the supply conduit.

7. A system according to claim 26, in which the system includes a valve for sealing the container when the latter is disconnected from the conduit.

A system according to any of claim 27, in which the value is a non-return valve for preventing the return of fluids from the conduit to the container on reconnection of the conduit.

9. A system according to any of claims 26 to 28, in which the system includes a further connector, attached to the conduit, which is releasably attachable to the first said connector to connect the container to the conduit, the further connector including a valve for preventing liquid exiting, or air entering, the conduit while the two connectors are disconnected from each other.

0. A container containing a degassed buffer solution for an instrument, the container including an internally tapered portion which leads to an outlet for the container, the arrangement being such that, when the container is orientated with its outlet uppermost, the tapered portion will guide any gas in the container to the outlet for expulsion therethrough.

1. A container according to claim 30, in which the outlet and tapered portion are included in an initially separate cap attachable to the container after the latter has been opened.

2. A container according to claim 30, in which the tapered portion is in a part of the container separate from any cap.