Abstract:
The application provides sample preparation devices and analyses. The devices and analyzes allow for the rapid preparation and analysis of samples using a variety of techniques, including PCR, by even unskilled users.

Description:
[0001]    CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
         [0002]    Applicants claim priority to GBRI Priority Application 0720264.1, filed Oct. 17, 2007 including the specification, drawings, claims and abstract, which is incorporated herein by reference in its entirety. 
       FIELD OF THE APPLICATION 
       [0003]    This application relates to sample preparation devices and analyzers. The application is more particularly concerned with devices for preparing biological samples into a form suitable for subsequent analysis. 
       BACKGROUND 
       [0004]    Analysis or detection equipment is available that can reliably identify specified biological substances by means of polymerase chain reaction (PCR) amplification and fluorescence identification. The polymerase chain reaction is a well known technique for amplification of small amounts of a specific DNA sequence to produce larger amounts of that specific DNA sequence, at which point the specific products can be identified or visualised in a number of ways. A variant of the polymerase chain reaction uses RNA as its input: reverse transcription of the RNA to its complementary DNA sequence is followed, optionally in the same reaction mixture, and optionally by the same enzyme, by polymerase chain reaction amplification of the complement DNA. 
         [0005]    This technique, although extremely powerful, is prone to inhibition by a wide variety of inhibitors, found widely in most sample types. There are well-established sample preparation methods in the prior art for addressing this issue, which rely either on the use of kits by trained molecular biologists, or the use of large laboratory robotic systems using reagents and plastic consumables. Portable PCR analysis equipment (such as the Bio-Seeq sold by Smiths Detection—Watford Limited) is available, which can be used easily with little training. Examples of preparation apparatus are described in WO05/121963, WO06/090127, WO06/079814, EP1383602, WO05/106040, WO05/019836 and GB0704035.5, which are hereby incorporated by reference in their entirety. 
       SUMMARY 
       [0006]    Provided herein are alternative sample preparation devices and analyzers. 
         [0007]    According to a first aspect there is provided an arrangement for separating magnetic particles from a fluid including a container of the fluid and magnetic particles having a tapering, closed lower end portion, and magnet means selectively positionable relative to the container adjacent its lower end, the magnet means including two magnet pole pieces aligned substantially parallel with the axis of the container and arranged to form regions for collection of the magnetic particles along the lower end portion and displaced from the lower end of the end portion. 
         [0008]    According to a second aspect there is provided an arrangement for separating magnetic particles from a fluid including a container of the fluid and magnetic particles, and magnet means movable between a first position where its magnetic field attracts the magnetic particles to a surface of the container and a second position where its magnetic field has substantially no effect on the magnetic particles, the magnet means being movable along curved path in a plane substantially at right angles to the axis of the container. 
         [0009]    According to a third aspect there is provided an arrangement for dispensing a fluid into a cuvette including a capillary tube open at both ends and extending within the cuvette with the lower end of the capillary in contact with the inside of the closed end of the cuvette and with the upper end of the capillary exposed at the upper end of the cuvette, the dimensions of the capillary and cuvette being arranged such that when the fluid is applied to the upper end of the capillary it flows to its lower end expelling air in the cuvette between the outside of the capillary and the inside of the cuvette. 
         [0010]    According to a fourth aspect there is provided a sample preparation device including an arrangement according to the above first, second or third aspects. 
         [0011]    According to a fifth aspect there is provided a sample preparation device including a fluid-transfer mechanism arranged to transfer material between different containers in the device, the mechanism having two components movable relative to one another to define a chamber of variable volume and a dispensing device connected with the chamber, the dispensing device being displaceable such that it can be raised and lowered relative the containers, the displacement of the dispensing device and the two components relative to one another both being brought about by rotary means. 
         [0012]    The two components preferably include a barrel and a piston. The rotary drive is preferably provided by an external unit to which the sample preparation device can be mounted and demounted. 
         [0013]    According to a sixth aspect there is provided a sample preparation device having a sample inlet including manual macerator means by which a fluid material is derived from a liquid, solid or semi-solid sample material preparatory to further preparation. 
         [0014]    The macerator means caninclude at least one reservoir of a treatment fluid protected by a breakable seal, the treatment fluid being brought into contact with the sample material by manual operation of the macerator means. The macerator means caninclude a rotatable macerator knob that seals the inlet and is screw threaded relative to the sample inlet such that rotation of the knob displaces it down to push the sample down through the macerator means. 
         [0015]    According to a seventh aspect there is provided a sample preparation device having a plurality of containers of substances used in preparation of a sample, a transfer device that is arranged to be raised and lowered and moved laterally relative to the containers to transfer substances between containers, the device including an absorbent material arranged to collect excess substance at the lower end of the transfer device. 
         [0016]    The absorbent material can be disposed on the upper surface of the containers and may be a fabric or non-woven material, for example. The sample preparation device can be arranged to lower the transfer device such that its lower end contacts the absorbent material when it is necessary to remove excess fluid from the end of the transfer device. 
         [0017]    According to an eighth aspect there is provided an analyzer arrangement including a PCR analyzer and a sample preparation device according to any one of the fourth to seventh aspects. 
         [0018]    According to a ninth aspect there is provided an analyzer arrangement including a base unit and a sample preparation device mountable with and demountable from the base unit, the sample preparation device including at least one container containing a mixture of a fluid and magnetic particles and the sample preparation device including means for extracting fluid from the container, the base unit including means operable to move magnet means selectively between a first position where a magnetic field from the magnet means attracts the magnetic particles to a surface of the container such that the fluid can be extracted and the magnetic particles retained in the container and a second position where the magnetic filed has substantially no effect on the magnetic particles. 
         [0019]    The magnet means can be movable along an arc in a plane at right angles to the axis of the container, and can be mounted on the sample preparation device. 
         [0020]    According to a tenth aspect there is provided an analyzer assembly including an analyzer and a sample preparation device mountable with and demountable from the analyzer, the sample preparation device including a plurality containers of substances for preparing the sample, some at least of the containers being provided together as a single component and at least one of the containers being provided separately of the component and being mountable with the component, the separately-provided container being provided with a machine-readable identification that can be read by the analyzer to control the analyzer to drive the sample preparation device in a particular sequence. 
         [0021]    The component providing at least some of the containers may be a circular carousel, which may be rotatable relative to the sample preparation device. 
         [0022]    According to an eleventh aspect there is provided a method of identifying a sample substance, including providing a sample preparation device having a plurality of installed containers of substances suitable for use in preparation of a range of different substances, providing a range of at least two separate containers containing different substances suitable for use in preparation of at least two respective different substances, selecting one of the separate containers according to the substance to be detected, installing the selected separate container with the sample preparation device, adding the sample substance to the sample preparation device and operating the sample preparation device to prepare the substance. 
         [0023]    According to a twelfth aspect there is provided apparatus for carrying out a method according to the above eleventh aspect. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    A portable sample analysis device assembly including an analyzer and a sample preparation device and its method of operation will now be described, by way of example, with reference to the accompanying drawings, in which: 
           [0025]      FIG. 1  is a perspective view of an exemplary analyzer assembly; 
           [0026]      FIG. 2  is a perspective view of an exemplary sample preparation device ( 2 ) from a side; 
           [0027]      FIG. 3  is a perspective view of the exemplary sample preparation device of  FIG. 2  from the opposite side of that shown in  FIG. 2 ; 
           [0028]      FIG. 4  is a side elevation view of the exemplary sample preparation device of  FIGS. 2 and 3  from one side; 
           [0029]      FIG. 5  is an end elevation view of the exemplary sample preparation device of  FIGS. 2 and 3 ; 
           [0030]      FIG. 6  is an enlarged cross-sectional side elevation view of a lower part of the exemplary sample preparation device of  FIGS. 2 and 3  showing a part of the drive mechanism; 
           [0031]      FIG. 7  is a view of the underside of the exemplary sample preparation device of  FIGS. 2 and 3 ; 
           [0032]      FIG. 8  is an enlarged excerpt of  FIG. 7  ; 
           [0033]      FIG. 9  is an enlarged cross-sectional side elevation view of a lower part of the sample preparation device of  FIGS. 2 and 3  showing a part of the cuvette filling arrangement; 
           [0034]      FIG. 10  is an exploded view of the sample inlet port of  FIGS. 2 and 3 ; 
           [0035]      FIG. 11  is a perspective view of the interior of the sample preparation device of  FIGS. 2 and 3 , with its housing removed and with the pipette in a raised position; 
           [0036]      FIG. 12  is a cross-sectional, side elevation view of the interior of the sample preparation device of  FIGS. 2 and 3  with the pipette in a lowered position for filling the cuvette; 
           [0037]      FIG. 13  is a perspective view of the outside of the sample preparation device of  FIGS. 2 and 3  showing the macerator knob and the reagent cartridge prior to insertion; 
           [0038]      FIGS. 14 ,  15  and  16  are cross-sectional side elevation views of the sample preparation device of  FIGS. 2 and 3  showing a macerator knob being inserted; 
           [0039]      FIGS. 17 and 18  are cross-sectional side elevation views of the sample preparation device of  FIGS. 2 and 3  showing stages in filling of a cuvette; 
           [0040]      FIG. 19  is a plan view of a mounting bay of an exemplary analyzer instrument; 
           [0041]      FIG. 20  is a sectional elevation view showing an interaction of a magnet assembly with a container of the carousel; 
           [0042]      FIG. 21  is an exploded perspective view of an exemplary reagent cartridge ( 27 ) as shown in  FIGS. 2 and 3 : 
           [0043]      FIG. 22  is a plan view of an exemplary carousel of a sample preparation device; 
           [0044]      FIG. 23  is a perspective view of the carousel of  FIG. 22 ; 
           [0045]      FIG. 24  is a cross-sectional side elevation view of an exemplary cuvette filling mechanism; and 
           [0046]      FIG. 25  is a perspective view showing how a pipette is mounted. 
       
    
    
     DETAILED DESCRIPTION 
       [0047]    With reference to  FIG. 1 , an assembly can comprise a combination of an analyzer or base unit  1 , by which analysis is carried out, and a sample preparation device  2  by which samples taken from the field can be prepared into a form suitable for analysis by the analyzer. The analyzer  1  can, optionally, include a rugged outer case  10  with a hinged lid  11  and a carrying handle  12 . The base  13  of the case  10  contains a PCR analysis instrument or other instrument capable of one or more suitable analysis methods. The instrument may use any suitable nucleic acid amplification method, such as, for example, conventional PCR or Linear After the Exponential PCR as described in, for example, U.S. Pat. No. 7,198,897. Thermocycling may be carried out using any acceptable method, such as, for example, conventional heating and cooling elements or thermoelectric elements. Detection may be achieved using any suitable method, such as fluorimetric methods. In one embodiment fiberoptic fluorimetry can be used. Conventional PCR analyzers are known, such as, for example, the Bio-Seeq analyzer available from Smiths Detection. The instrument may also use any suitable analytical techniques or a combination of analytical techniques, including mass spectrometry, gas spectrometry, ion mobility spectrometry, and antibody binding methods, for example. In one embodiment, the lid  11  of the case can support, on its inside surface, a display screen  14 , such as an LCD screen or an touch screen. The LCD touch screen can be used to input instructions to control the device or to display information, such as the results of analysis or system parameters. The sample analysis device can include any number of mounting bays each adapted to receive a sample preparation device. In one embodiment, the upper surface  15  of the analyzer base  13  can have any number of mounting bays  16 . In another embodiment, the upper surface  15  of the analyzer can have five mounting bays  16 , arranged in any configuration, such as, for example a row, to which five different sample preparation devices  2  (only two shown fitted in  FIG. 1 ) can be removably fitted. In another embodiment, the analyzer can have auxiliary, for example, slave, mounting bays that can communicate with the master analyzer. It will be appreciated that the analyzer could have any number of one or more bays  16  to which sample preparation devices  2  are fitted. 
         [0048]    In one embodiment, the analyzer  1  can be sealed against ingress of fluids, and all external surfaces can be resistant to normal cleaning fluids. In a further embodiment, the analyzer is substantially completely sealed against ingress of fluids. This enables the analyzer to be immersed in a cleaning fluid, with the case  10  open or closed, to ensure that any harmful substances on the analyzer are rendered harmless. The analyzer  1  is capable of carrying out sample analysis, such as PCR analysis, on each of the samples prepared by sample preparation devices  2  at the same or at different times. This enables the sample preparation devices  2  to be fitted to the analyzer  1  as and when they become available and for the sample preparation stages for each sample to be started immediately. The devices can be fitted so that the analysis can take place as soon as the samples have been appropriately prepared. In one embodiment, the analyzer  1  can provide all the motive power for the sample preparation devices  2  through appropriate mechanical couplings, for example, to be described later, so that the sample preparation devices do not themselves need to include any motor or battery. This helps to keep the cost, size and weight of the sample preparation devices  2  to a minimum and reduces disposal problems, volume, and cost. 
         [0049]    With reference now also to  FIGS. 2 to 9 , an exemplary sample preparation device  2  will be described in greater detail. The device  2  can include an outer housing  20  of any suitable material and shape. In one exemplary embodiment, the outer housing can be a molded plastic outer housing  20  of generally oval section. In this exemplary embodiment, the housing  20  has a base section  21  with an inclined upper surface  22 , a substantially triangular, wedge-shape fluid transfer enclosure  23  extending to about twice the height of the base section and having a upper surface  24  inclined at a slightly shallower angle than that on the base. The height of the enclosure  23  can be any suitable height. In one embodiment, the enclosure height can be about 100 mm. The housing  20  also can have a inlet cylinder  25  extending approximately vertically up to the same level as the top of the upper surface  24 . The upper surface  22  of the base section  21  is interrupted by an elongated slot  26  extending along side one side of the enclosure  23 . This slot  26  can be used to fit a reagent cartridge  27 , to be described in more detail later. 
         [0050]    In the exemplary embodiment shown in  FIGS. 2-9 , on the underside  28  of the housing  20  are mounted two rigid alignment tongues  29 , which project substantially vertically down. In one embodiment, the alignment tongues can be from approximately 10 mm to approximately 50 mm and in a further embodiment the alignment tongues can be approximately 39 mm. The tongues  29  can be arranged in any suitable arrangement and can be rounded at their lower ends  30  and can be closely spaced from one another. The tongues  29  can be shaped and positioned to align with alignment apertures  129  ( FIG. 19 ) located in the bays  16  on the analyzer  1  to ensure correct alignment of the preparation devices  2  with respect to the bays. The length of the tongues  29  also ensures that the preparation devices  2  can only be loaded on the analyzer  1  when oriented substantially vertically with respect to the upper surface  15  of the analyzer. Also projecting substantially vertically downwards from the underside  28  of the device  2  is a cuvette  30  into which the prepared sample is dispensed for analysis. The cuvette  30  can be quite delicate and the alignment tongues  29  ensure that it is correctly aligned with a reception aperture  130  ( FIG. 19 ) in the bay  16  during loading of the device  2  on the analyzer. When the cuvette  30  is loaded in the reception aperture  130 , it extends into, for example, a PCR analysis module for that bay so that material in the cuvette is subject to PCR analysis. The cuvette  30  will be described in greater detail later. During storage and before use of the sample preparation device  2 , a removable cap  31  ( FIG. 13 ) can be fitted over its lower end to protect the cuvette  30 . This cap  31  can be removed just before loading the device into the mounting bay  16 . 
         [0051]    In an exemplary embodiment, the underside  28  of the housing  20  also can include three mechanical, rotary drive input couplings  40 ,  41  and  42 . One coupling  40  can be located centrally and the other two  41  and  42  can be located close to the edge, in respective corners of the enclosure  23 . The input couplings  40  to  42  each can take the form shown in  FIG. 6  of a tapered socket  43  of square section in the end of a vertically-oriented drive shaft  44 . Each socket  43  is adapted to receive a correspondingly-shaped male head of a respective drive element  140  to  142  ( FIG. 19 ) located in each bay  16  on the analyzer  1  and mechanically connected to respective motors (not shown) in the analyzer. A magnet assembly  45  (shown in more detail in  FIG. 20 ), which can be movable in, for example, a substantially horizontal plane along two parallel slots  46  and  47 , also can be provided on the underside  28  of the housing  20 . The slots  46  and  47  can be arcs curved in, for example, a part-circular shape with a common radius centered on the central drive coupling  40 . 
         [0052]    The internal features of an exemplary preparation device  2  will now be described with reference to  FIGS. 10 to 18 . 
         [0053]    An exemplary sample inlet  25  is shown in more detail in  FIGS. 10 ,  14 ,  15  and  16  and includes within it a sample homogenization module  50  of cylindrical shape and containing a displaceable macerator plate  51  of an open construction above a reservoir  52  containing a lysis/binding buffer with breakable seals  53  and  54  (such as of a foil) on its upper and lower surface. The module  50  can be positioned above filter  55  held in place between O-ring seals  56  and  57 . The filter  55  can be made of any suitable material, including polypropylene, and can be coarse. The inlet  25  can be completed by a macerator knob  58 . In one embodiment, the macerator knob can have a surface configured to ease hand turning, such as a friction-enhancing surface or a knurled outer surface  59 . The macerator knob also can include a screw-threaded inner surface  60 , which engages a screw thread  61  on the outside of the inlet  25 . The knob  58  can have a coaxial plunger  62  on its inside, which makes a close sliding fit in the bore of the inlet  25 . The knob  58  can be removed to insert the sample and is then screwed down to effect maceration. 
         [0054]    The sample may be any suitable sample, including, but not limited to any bodily fluids, blood, sputum (respiratory tract secretions/scraping), milk, feces; solid unknowns, including powders (such as anthrax spores), soft tissue (skin, muscle, hair follicle, vesicle), vegetable materials, and soil. Other sample substances or mixtures of substances also are possible. 
         [0055]    After the sample has been placed in the inlet  25 , the knob  58  can be replaced and manually screwed down so that its plunger  62  is also moved down to engage and move down the macerator plate  51 , as shown in  FIG. 14 . The plate  51  pushes through and breaks the seal  52  on the upper surface of the buffer reservoir  50 , which can hold, for example, lysis/binding buffer, so that the sample is exposed to this liquid, as shown in  FIG. 15 . The lysis/binding buffer releases nucleic acids from the sample and inactivates nucleases so that the nucleic acids come out into solution. The lysis and nuclease inactivation steps can be performed together or separately. In one embodiment, the lysis and nuclease inactivation steps are performed at approximately the same time. In this exemplary embodiment, further rotation of the macerator knob  58  causes its plunger  62  to break through the lower seal on the reservoir  50  and pushes the mixture of the sample, lysis and binding buffer down through the filter  55 , as shown in  FIG. 16 . 
         [0056]    The mixture can drop by gravity from the filter  55  into the first container or pot  75  in a rotatable carousel  70 , labeled “A” in  FIG. 22 . In an embodiment, the carousel  70  can be molded of a plastics material having a circular shape with a central, circular aperture  71 . A toothed rack  72  extends around the outside of the carousel  70  at its lower end, which can be used to rotate the carousel about its axis. The rack  72  is engaged by, for example, a pinion wheel  73  ( FIG. 11 ) mounted at the edge of the base of the housing  20  and which is rotated by its input drive coupling  41  when engaged by the drive coupling  141  on the analyzer  1 . Internally, the carousel  70  is divided into wedge shape recesses (also referred to herein as pots or containers)  75  of varying sizes, most of which provide containers or pots for use in the various treatment stages to which the sample is subjected. In one embodiment, the carousel is divided into five to 20 pots, and in a further embodiment, the carousel is divided in to 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 19, or 19 pots. The pots  75  can contain various substances with which the sample can be mixed to produce a product prepared in a form suitable for analysis. Some of the pots  75  can be left empty for mixing purposes or containing waste material. In general, the pots  75  may contain various of the following: buffers of various pH and composition; enzymes (including nucleic acid modifying enzymes of various kinds in aqueous or freeze-dried form); deoxynucleotides; metal ions; oligonucleotides (including those labelled with reporter molecules such as fluorophors); and proteins. All the pots  75  containing a reagent or treatment substance can be covered before use by a pierceable covering  76 , such as, for example, a foil covering, to prevent escape of the contents. On top of the covering  76  there can be an upper cover having an exposed upper surface layer  77  of a fluid-absorbing material, such as a wadding of paper, fabric, woven or non-woven or a coating of absorbent chemical. The upper cover can have an impermeable base of a plastics material, not shown. The purpose of this will become apparent later. The upper cover and layer  77  is cut with small openings  78  to expose the underlying cover  76  in alignment with the pipette  110 . The first pot “A” is relatively large and is empty before it receives the sample mixture. By way of example, for a PCR analysis reaction, the pots labeled “B”, “C”, “D”, “E”, “I”, “J”, “K”, “L” and “M” can contain the following substances:
   B—empty at start   C—lysis binding buffer   D—wash buffer No 1   E—wash buffer No 2   I—wash buffer No 3   J—empty—used for waste from lysis   K—elution buffer   L—DNAse buffer   M—proteinase K and magnetic beads   
 
         [0066]    According to the particular substances being prepared, it will be appreciated that different treatment substances could be used and that different numbers of pots  75  could be provided. The sample preparation device  2  can be used in a range of at least two different preparation sequences, such as for use in preparing samples for detection of different substances. Some of the treatment substances and preparation steps are common to the range and these treatment substances can be provided in the pots “B”, “C”, “D”, “E”, “I”, “J”, “K”, “L” and “M”. Others of the treatment substances vary for the different preparations and these can be provided in a cartridge  27  ( FIG. 21 ) provided separately of the sample preparation device  2  and inserted into it prior to use. 
         [0067]    The cartridge  27  can be shaped to extend in the elongate slot  81  extending at right angles to a radius of the carousel  70 . The cartridge  27  can be inserted through the slot  26  in the top surface  22  of the device  2 . When the cartridge  27  has been loaded, it can lock with the carousel  70  and can be rotated with it. The cartridge  27  has separate pots  82  containing all the reagents that are specific to the particular assay to be carried out by that cartridge. The reagents can be in any form, such as solid, dried or liquid form. The reagents, if solid or dried, can be hydrated during operation by aqueous substances stored in other pots in the carousel. In a PCR analysis, for example, the reagents may include one or more of the following, namely: nucleic acid modifying enzymes (including DNAses, RNAses and restriction endonucleases); PCR primers; PCR probes; polymerases; reverse transcriptases; dual-mode enzymes such as polymerase/reverse transcriptase; and antibodies. Other reagents are possible. A sleeve  85  at the lower end of the cartridge  27  can be shaped such that it is pushed up during insertion via the slot  26  to enable the cartridge to be loaded in the carousel  70 . The pots  82  to  84  can be covered by a breakable cover seal  85 , such as a foil seal, or the like and, optionally, by a protective cap  86 , such as a molded cap. On its upper surface the cap  86  can carry a machine-readable identification, such as, for example, 2-D barcode  87  or some other form of machine-readable identification, such as an electronic memory chip or RFID. A machine-readable identification  87  on the cartridge  27  can be held up to a reader  88  adjacent the mounting bay  16  in which the preparation device  2  is inserted. The reader can be separate from the analysis device, such as, for example, a handheld readers. The analysis instrument  1  can recognize the machine-readable identification code, and based on information contained in the machine-readable identification code, instruct the module associated with that mounting bay  16  to drive the preparation device  2  to carry out the necessary steps associated with the sample and reagents. It also can instruct the analysis instrument  1  to make the appropriate PCR thermal cycling and data analysis operations for the particular substance being detected. 
         [0068]    By supplying the specific reagents in a cartridge separately from the rest of the sample preparation device, the cost of providing sample preparation devices for different substances can be kept to a minimum. The user does not need to stock a range of different sample preparation devices for different substances but need only stock the different reagent cartridges and a smaller number of common sample preparation devices. 
         [0069]    The mixture of the sample substance added via the inlet  25  can be exposed to the reagents and other treatment substances by means of, for example, a syringe pipette mechanism  90 , shown most clearly in  FIGS. 11 ,  12 ,  17 ,  18  and  25 . The mechanism  90  can consist of two main parts: a syringe assembly  91  and a pipette assembly  92 . The syringe assembly  91  can extend axially through the central aperture  71  in the carousel  70  and can be operable to effect pumping of fluid. The pipette assembly  92  can be mounted on a vertical elevator shaft  93  at the edge of the carousel and can be movable vertically up and down. The pipette assembly  92  and syringe assembly  91  can be connected via a length of flexible tubing  94 . The syringe assembly  91  can have a central, axial worm shaft  95 , which is externally threaded and, at is lower end provides the central drive coupling  40 . The shaft  95  is fixed against axial displacement but is freely rotatable about its axis. Surrounding the shaft  95  is a cylindrical plunger  96 , which can close at its upper end  97  and can be internally threaded in engagement with the external thread on the shaft  95 . The syringe assembly  91  can be completed by an external hollow barrel  98 , which can be fixed against axial or rotational movement. The upper end of the barrel  98  can be formed with a reduced diameter nose  99  to which one end of the tubing  94  is fixed. The upper end of the plunger  96  can support an O-ring  100 , which makes a sliding seal with the inside surface of the barrel  98 . The plunger  96  is shaped or provided with a surface formation to prevent it rotating relative to the barrel  98  so that, when the shaft  95  is rotated this is translated into axial displacement of the plunger along the inside of the barrel, so as to vary the volume of the chamber or potential space  101  at the upper end of the barrel. It can be seen, therefore, that rotation of the drive shaft  95  can be effective to cause pumping of air along the tubing  94 . 
         [0070]    The pipette assembly  92  can include a pipette  110  made of any suitable material and manufactured in any suitable way. In one embodiment, the pipette assembly  92  can be molded of a plastics material. The pipette  110  can have an elongate, tapering, vertically-oriented hollow stem  111  opening at its upper end into a closed conical receptacle  112 . The receptacle  112  can have a small-bore spigot  113  projecting laterally generally towards the syringe assembly  91  and can receive the other end of the tubing  94 . The internal volume of the stem  111  and receptacle  112  can be selected to be sufficient to contain any volume of liquid to be transferred by the pipette  90 . In this way, it can be seen that operation of the syringe assembly  91  can be effective to pump air or gas above the liquid in the receptacle  112  and that no liquid need flow through the tubing  94  into the syringe chamber  101 . 
         [0071]    The pipette  110  can be supported by an arm  115 , which extends laterally of the pipette and can be terminated by a threaded nut  116 . The nut  116  can embrace the elevator shaft  93 , which can be externally threaded and which can provide at its lower end the input drive coupling  42 . It can be seen that the pipette  110  can be raised or lowered by appropriately rotating the elevator shaft  93  in different directions. In this way, both actuation of the syringe  91  and displacement of the pipette  110  can be accomplished by rotational drive inputs. 
         [0072]    Fluid can be transferred between pots  75  in the carousel  70  by rotating the carousel so that the appropriate pot is positioned directly below the pipette  110 ; lowering the pipette into the pot (breaking through the seal  76  if this has not already been broken); displacing the syringe  91  to cause a reduced pressure in the pipette  110  and thereby suck up the fluid into the pipette; raising the pipette to allow the carousel to be rotated to position the desired pot directly beneath it; lowering the pipette into the pot; and then driving the syringe to increase gas pressure above the fluid in the pipette and force it out into the pot. Mixing within the pots can be promoted by repeatedly sucking and expelling fluid into the pipette  110  so as to cause flow of fluid within the pot. Each pot  75  can be shaped with a tapering V-shape floor provided by two planar inclined surfaces. The lowest point can be located centrally, in line with the stem  111  of the pipette  110  so that the tip of the pipette can be lowered into the lowest point to enable extraction of the maximum amount of fluid from the pots. 
         [0073]    During various of the fluid transfer stages of the preparation device  2  it may be desirable to prevent contamination of certain fluids by other fluids that have previously been transferred by the pipette. Even dispensing the entire contents of the pipette would not guarantee complete removal of its contents since some fluid could remain clinging to the tip of the pipette. Some previous arrangements have overcome this problem by changing the tip of the pipette but this complicates operation of the apparatus. The risk of contamination can be reduced by arranging for the device to lower the tip of the notionally-empty pipette  110  onto the layer  77  of fluid-absorbing material on top of the carousel  70 , whenever it is necessary to prevent transfer of fluid. Any fluid clinging to the tip of the pipette  110 , either on its outside or inside can be wicked away from the pipette by the absorbent material  77  and remains trapped in the material. This provides a simple, low-cost arrangement for preventing undesirable fluid transfer. In some cases, however, the pipette can be replaced to avoid the risk of contamination, such as when the sample is potentially dangerous. 
         [0074]    In an embodiment, paramagnetic beads can be used to capture nucleic acid in the sample, and the beads can be subsequently washed to remove unwanted substances whilst retaining the nucleic acid for subsequent treatment or release, according to methods well-known in the art. The beads can be stored in aqueous solution in the pot “M” of the carousel  70 , for example. The beads can be washed in the usual way by using a magnet to draw the beads with the nucleic acid bound to them out of suspension to a location and retaining the beads there while unwanted material is removed. The magnet assembly  45  ( FIG. 20 ) can comprise two permanent bar magnets  121  and  122 . The magnets  121  and  122  can be mounted substantially parallel to one another and substantially vertically on a lateral, horizontal polepiece  123 . The pole-piece  123  can be comprised of any suitable material, such as, for example, soft-iron. The two magnets can be oriented in opposite senses so that the north pole of one  121  and the south pole of the other  122  is uppermost. When not required, the magnet assembly  45  can be located at the far end of the slots  46  and  47  away from the pipette station. When magnetic separation is to be carried out, the analyzer  1  can displace a carriage  124  along a slot  125  in the upper surface of the mounting bay  16  to engage and displace the magnet assembly  45  along the slots  46  and  47  so that it moves to a position directly below the pipette  110 . In this position, the two permanent magnets  121  and  122  are located on opposite sides of the carousel pot  75  directly below the pipette  110  (as shown in  FIG. 20 ) so that the magnetic field set up by the magnet assembly  45  passes through the wall of the pot and into the fluid and magnetic bead suspension. The magnet assembly  45  can be arranged such that the magnetic field can be concentrated in two localized regions  127  and  128  on opposite sides of the tapered floor of the pot  75  and spaced above the lowest point or sump region  129 . Magnetic beads are, therefore, attracted to these two regions  127  and  128 , leaving the sump region  129  clear of beads so that the tip of the pipette  110  can be lowered into this region and the maximum volume of fluid extracted. The magnet assembly  45  is then moved back to its original position to allow the magnetic beads to move freely in the next fluid added to the pot  75 . 
         [0075]    As an example, the sample preparation device  2  can be arranged to carry out the following steps:
       1. Acceptance of a sample into the device   2. Maceration and/or mixing of the sample with a volume of lysis/binding buffer to inactivate nucleases and release nucleic acids from the sample.   3. Mixing of the macerated sample with a further volume of lysis binding buffer, to release nucleic acid from the sample.   4. Mixing of the sample with a substance, such as proteinase K, to further break down the sample and release nucleic acids.   5. Capture of the nucleic acid so released onto paramagnetic beads, for example.   6. Washing of the nucleic acid (including the beads in some embodiments) with a defined buffer.   7. In the case where the target nucleic acid is RNA, optional incubation of the washed nucleic acid with a solution containing DNAseI.   8. In the case where the target nucleic acid is DNA, optional incubation of the so washed nucleic acid with a solution containing RNAse.   9. Further wash(es) of the nucleic acid with one or more defined buffers.   10. If beads were used, mixing of the beads bearing the target nucleic acids with a solution which elutes off the target nucleic acid.   11. Incubation of this eluate with a mixture of optionally freeze-dried nucleic acid primers and probes.   12. Incubation of the mixture formed in 11 with one or more freeze-dried DNA modifying enzymes or polymerases.   13. Transfer of the mixture formed in 12 to the PCR cuvette  30  via a cuvette filling mechanism.   14. Withdrawal of the cuvette filling mechanism from the cuvette  30 .   15. Addition to the top of the cuvette a quantity of a material such as light mineral oil, or other materials to prevent subsequent evaporation of the mixture.       
 
         [0091]    After these steps have been carried out the mixture within the cuvette  30  can be placed to carry out thermocycling to effect any suitable reaction, such as, for example, PCR, LATE-PCR, reverse transcriptase (RT)-PCR, within the analyzer  1 . 
         [0092]    An exemplary cuvette filling mechanism is shown in more detail in  FIGS. 9 ,  17 ,  18  and  24 . In this example, the cuvette  30  can be of conventional form being molded from an optically-transparent plastics material suitable for use in the PCR reaction and optical detection steps in the analyzer  1 . The cuvette  30  can be fixed in position vertically in an aperture  138  in the floor  28  of the housing  20  and does not move with the carousel  70 . It is in alignment, directly below the pipette  110 . When the cuvette  30  is to be filled, the pipette  110  can be loaded with fluid and the carousel  70  is rotated until a circular aperture  131  immediately to the left of the first pot “A” is located above the cuvette, so that the upper end of the cuvette is exposed for access by the pipette. The cuvette filling mechanism can comprise a plastics capillary tube  140 , which is open at both ends and is located to extend within the cuvette  30  to contact the inside of its lower end  141 . The upper end of the capillary  140  has a tapering coupling  142  fitted to it, which is shaped to engage with the outside of the tip of the pipette  110 . The capillary  140  is a free sliding fit within the cuvette  30  allowing a gas venting clearance around it. To fill the cuvette  30 , the pipette  110  can be lowered to engage with the coupling  142  on the capillary  140 , as shown in  FIG. 17 , and the syringe  91  can be actuated slowly to pump out the fluid in the pipette. The fluid flows down the capillary  140 , the clearance between the outside of the capillary and the inside of the cuvette  30  being sufficient to allow air to vent from the cuvette as it is filled with fluid. The fluid can flow out of the bottom end of the capillary  140  and can wick up into the annular clearance between the outside of the capillary and the inside of the cuvette. The pipette  110  can then be raised, taking with it the capillary tube  140 , which can be attached by the coupling  142 , as shown in  FIG. 18 . The next action, as mentioned in step 15 above, can be to index the carousel  70  one station clockwise so that a small oil reservoir  150  is located below the pipette  110 . The capillary tube  140  attached to the end of the pipette  110  can be lowered into the oil reservoir  150  and its contents aspirated into the pipette. The carousel  70  can then be indexed back by one station anticlockwise and the capillary  140  can be lowered into the upper end of the cuvette  30  to dispense a small quantity of oil onto the top of the fluid in the cuvette  30  to prevent evaporation. 
         [0093]    The analyzer  1  with which a sample preparation device is used could include provision to record the location of the analyzer so that this information can be stored with the results of analysis. The location information could be entered manually or via an internal or external GPS or similar positioning system. The analyzer also can be capable of transmitting the location of the analyzer to a remote location. For example, the analyzer can transmit its location to a remote location at periodic intervals, when prompted by the user, or whenever an analysis is performed. 
         [0094]    Although the sample preparation device is particularly suited to preparation of biological samples for PCR analysis and related techniques, it could also be used for preparing other samples for analysis by different analyzers. 
         [0095]    Where the prepared sample in the cuvette is of biological origin the reactions or transformations that take place during analysis may typically include any of the following: polymerase chain reaction (including variants thereof, including Linear After The Exponential (LATE) PCR); reverse transcription; exonuclease activity; endonuclease activity; and hybridisation or binding with other reagents such as oligonucleotides or antibodies. Other reactions and transformations are also possible. 
         [0096]    The device described herein can be adapted for use in any location, such as in the field or in a stationary setting, such as, for example, a doctor&#39;s office, clinic or laboratory. The device described herein can allow an unskilled user to perform the sample preparation for PCR, and the PCR itself, in a small, self-contained, single-use consumable, which is controlled entirely by a field-portable instrument, and requires no knowledge of molecular biology. The device could be used in veterinary applications to prepare samples for detection of, for example. foot and mouth, avian flu and blue tongue or other diseases. The device enables rapid detection to be carried out in the region from where the samples are obtained so that rapid action can be taken if the a disease is detected. If a negative response is produced it avoids the need to take unnecessary, costly precautionary measures of the kind that would be necessary if the sample had to be sent to a remote location for laboratory analysis.