Abstract:
The disclosure relates to an in-hand operable compressor  200  for compressing syringeless filter devices  100.  The compressor  200  includes a base  220  having a receiving well  222  adapted to receive a bottom portion of the uncompressed device  100,  and a discrete top  210  having a receiving recess ( 212  FIG.  4 ) adapted to receive a top portion of the uncompressed device  100,  said base and top being brought together in use by hand compression to cause compression of the device  100  located in the well and recess of the compressor. Surface formations  250  and  252  (FIG.  2 ) are complementary and inhibit misalignment of said well and recess during the in-hand compression.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a manually operable compressor for compressing syringeless filter devices used in filtering laboratory sample liquids. 
       BACKGROUND OF THE INVENTION 
       [0002]    Filtration devices are frequently employed in laboratory and other environments to remove solids or particulates from a liquid sample. Liquid samples, for example, filtration of a pharmaceutical drug (that has been dissolved in a suitable solvent) to remove insoluble excipients prior to quantitative analysis of the active pharmaceutical ingredient(s). The filtrate may then be used to perform laboratory tests, such as high-performance liquid chromatography (HPLC) analysis. 
         [0003]    Some laboratory filtration devices, typically referred to as “syringe filters”, require a standard laboratory syringe, into which a liquid sample to be filtered is drawn. A syringe filter is then fitted to the tip of the syringe and the syringe plunger is compressed, forcing the liquid sample contained within the syringe through the syringe filter into a separate receptacle. However, use of syringe filters according to the above procedure can be time consuming, and due to the number of components required, can be relatively costly. 
         [0004]    Alternative laboratory filtration devices, referred to as “syringeless filters”, in which no syringe is used have been developed, such as the commercially available Whatman™ Mini-Uniprep™.  FIG. 1  shows an exemplary syringeless filter device  100 , in assembled form. The device  100  comprises a vial  102  (typically having a capacity of approximately 0.4 ml) for holding a liquid sample to be filtered. The device  100  also comprises a hollow plunger  106  having a filtration membrane at one end, and a pre-attached cap  110  at the other end. During filtration, the device  100  is compressed so that the plunger  106  slides towards the bottom of the vial  102 ; as the plunger  106  slides, a seal on the exterior walls of the plunger  106  engages with the internal walls of the vial  102 , preventing the liquid sample  104  from passing around the outside of the plunger  106 . Accordingly, the liquid sample is forced through the filtration membrane, and into the interior of the plunger  106  where it collects as a filtrate, leaving filtered particles in the bottom of the vial  102 . The filtrate can then be stored or transported in this state for extended periods (typically up to several days) until it is needed, at which time it may be removed from the plunger by, for example, using a syringe needle to pierce a septum  120  in the cap  110 . 
         [0005]    Whilst the term “syringeless filter device” is used herein, an equivalent term often used is “filter vial”, as in the case of the Thomson SINGLE StEP™ Filter Vial device; such devices perform the same function as the syringeless filter device described above and may be operated in the same way. 
         [0006]    Syringeless filter devices such as those described above are simpler to use than syringe filters. 
         [0007]    The step of compressing the syringeless filter device may be performed manually, with a human operator pressing the plunger into the vial using their hand. However, this may be time consuming, and can be uncomfortable for the operator, since the force required to push the plunger into the vial may be significant, due to the resulting back-pressure from the filtering described above. Further, the compression process can result in breakage of the syringeless filter device where too much compression force is used, especially where glass components are used. This poses a risk of injury to the operator, as well as potentially bringing him or her into contact with the sample to be filtered; in particular, where the sample is held in a potentially harmful solvent such as acetonitrile or methanol, such contact is undesirable. 
         [0008]    The Whatman™ Six Position Compressor™ is a device for compressing multiple syringeless filter devices in a single action. The device comprises a base fixed to a hand lever via a pivot. The base includes six shallow recesses, arranged in a straight line, for locating syringeless filter devices for compression. In use, the hand lever is raised to allow an operator to individually locate each of the uncompressed syringeless filter devices in the recesses. The operator then brings down the hand lever to a horizontal position in a swinging motion about the pivot. Consequently, the lever pushes downwards onto each of the syringeless filter devices, and compresses them, in turn. Although this compressor is satisfactorily for existing products, the introduction of glass chambers in syringeless filters has meant that a purely vertical compressive force is desirable so that the glass chambers are not subjected to side loads. Also, a simpler and cheaper device is desirable for smaller numbers of compressions. 
         [0009]    In embodiments, the present invention address the problems mentioned above by providing a simple in-hand operable syringeless filter compressor device. 
       SUMMARY OF THE INVENTION 
       [0010]    In accordance with a first aspect of the present invention, there is provided a hand operated compressor suitable for compressing a syringeless filter device in use, said compressor including a base having a receiving well adapted to receive a bottom portion of the uncompressed device, and a top having a receiving recess adapted to receive a top portion of the uncompressed device, said base and top being relatively moveable to allow compression of the device located in the well and recess of the compressor, the base and top including also complementary formations inhibiting misalignment of said well and recess. 
         [0011]    Thereby, misalignment of the compressor base and top is reduced or eliminated because the base and top can be brought together in a generally aligned manner. 
         [0012]    In an embodiment, the well and recess each have an axis, coinciding generally with the direction of said movement, and said complementary formations include surfaces extending generally radially away from the well and recess axes respectively. 
         [0013]    Thereby, said surfaces may abut in use to prevent relative tilting of the base and the top, and hence keep the device parts aligned during compression movement to provide the inhibition of misalignment. 
         [0014]    Preferably, the surfaces extend substantially perpendicularly to said axis. 
         [0015]    More preferably, the base or top includes a substantially axially extending collar such that there is no clear radial linear path between the axis and any point external to the compressor at least during said latter third of the compression movement. 
         [0016]    In an embodiment, the base and top have further complementary formations, which are alignable by relative axially rotation of the base and top to allow a final compression movement of the base and top. 
         [0017]    Preferably said final compression movement is approximately 1 mm 
         [0018]    In this way, the device can only be completely compressed with full alignment of the base and top, and so misalignment is not possible. 
         [0019]    Preferably, the compressor comprises at least a portion of a transparent or translucent material whereby at least a part of the well is visible externally. 
         [0020]    Preferably, the compressor comprises a channel extending from the well to the external wall, and the transparent or translucent material is a discrete part located in a groove formed in opposing sides of the channel. 
         [0021]    Preferably, compressor has a substantially circular section perpendicular to the axis and preferably the compressor is substantially barrel shaped, when the base and top are brought together. 
         [0022]    Thereby, the compressor is comfortable in the hand of a user. 
         [0023]    Preferably, the base and top are discrete pieces, preferably formed from substantially separate mouldings, for example, plastics mouldings. 
         [0024]    In accordance with a second aspect of the invention, there is provided a method for compressing a syringeless filter device by hand, including the step of: providing a syringeless filter device, containing a liquid sample to be filtered; providing a compressor having a base and a top which are relatively moveable, the base including a well and the top including a recess; manually inserting the device into a well and into the recess; and by in-hand movements, bringing together a top and a base of a compressor, thereby compressing the device and filtering said liquid sample during said movement; the base and top each having complementary formations for inhibiting their misalignment during said in-hand movements. 
         [0025]    In accordance with a third aspect of the invention there is provided, a syringeless filter device when used with the compressor of the first aspect, or when used in the method of the second aspect. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    Although, aspects of the invention have been set out above, the invention can be put into effect in numerous ways, one example only of which is described below with reference to the drawings, wherein: 
           [0027]      FIG. 1  is pictorial view of an exemplary compressor for a syringeless filter device and a syringeless filter device shown also in this Figure; 
           [0028]      FIG. 2  is a side view of the compressor in the direction of arrow II in  FIG. 1 , with the syringeless filter device inserted within the compressor; 
           [0029]      FIG. 3  is a pictorial side view of the now substantially compressed compressor, viewed in the direction of arrow III in  FIG. 1 ; 
           [0030]      FIG. 4  is a sectional pictorial view of the compressor and device in the substantially compressed state; and 
           [0031]      FIGS. 5 and 6  are pictorial views of two different further examples of a compressor device. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]      FIG. 1  shows a known syringeless filter device  100 , which is also referred to as a filter vial, as previously described.  FIG. 1  shows also a novel syringeless filter device compressor  200 , which comprises a base  220  and a separate top  210 . The filter  100  is placed into a well  222  in the base and the top is brought down onto the cap  110  of the device  100  to compress it. The cap  110  sits in a recess  212  (shown in  FIG. 4 ) in the underside of the top  210  . In use the top and base are held in a user&#39;s hand and are shaped and sized such that the compressor fits comfortably in one hand during the compression. The compressor is barrel shaped, in this case with generally flat ends  211  and  221  and curved cylindrical sides  213  and  230 . By experimentation, it has been found that this is a comfortable shape for in-hand compression. The compressor can also be used on a bench or worktop, by pressing the top onto the base , as the base sits on the bench or worktop. In each case the compressor is operated by hand. 
         [0033]    In  FIG. 1  a window  224  is visible, which is formed from transparent plastics sheet material held within grooves  226 , formed in the sides of a viewing channel  228  which in turn extends from the well  222  to an external wall  230  of the compressor base  220 . The window allows the operator to visually inspect the progress of the compression movement. 
         [0034]      FIG. 2  shows a side view of the compressor  200  with the device  100  awaiting compression generally along an axis A. Compression is accomplished by relative manual movement of the base  220  and top  210  together by a distance X of around 10 to 20 mm along axis A. Here, it can be observed that the compressor  200  has formations  250  and  252 , described in more detail below, which will prevent substantial misalignment of the base and top about axis A, during compression of the device  100  at least during the latter part of the compression, and increasingly so, as compression progresses. 
         [0035]      FIG. 3  shows the compressor  200  now substantially compressed. Indicia  232 , formed on the top  210  and base  220  show the correct alignment of these parts to complete the compression step which is accomplished by said alignment, and further compression by a distance x, which is about 1 mm. 
         [0036]      FIG. 4  is a sectional view corresponding to  FIG. 3 . In this view the substantially compressed device  100  is visible within the compressor  200  awaiting a final compression by the distance x. The formations  250  and  252  are shown, which in this embodiment, are generally flat surfaces extending radially away from the axis A. Thus the top  210  and base  220  cannot tilt excessively with respect to the device  100 , and as compression progresses, the amount of tilting possible decreases because the surfaces  250  and  252  come closer together. 
         [0037]    In addition, a collar  254  extends from the outer periphery of the surface  250 , and extends in a generally axial direction. The collar  254  is complemented by an annular groove  256 , which receives the collar during compression. The collar and annular groove also act as complementary formations to inhibit misalignment. Further, the collar  252  acts to shield a user from the device  100  during the latter stages of compression, because the collar extends to obscure the device  100 , and so any bursting parts of the device  100  will not travel directly toward a user&#39;s hands. 
         [0038]    Further formations  260  and  262  in the top and base respectively, act to prevent final compression, until they are aligned about the axis A. Twisting of the top relative to the base brings the formations  260  and  262  into alignment, and the last x distance of compression can be completed. In this embodiment, the formation  260  is an incomplete annular protrusion, and the formation  262  is a generally equally incomplete annular groove. Until the protrusion  260  and groove  262  are aligned the protrusion  260  cannot fall into the groove  262 . Thus the user cannot complete the compression quickly, without aligning the top and base accurately, and the user cannot fully compress the device  100  suddenly. 
         [0039]    The dimensions of the syringeless filtration device compressor  200  are typically selected dependent on the syringeless filtration device  100  with which the syringeless filter device compressor  200  is to be used. In the case of Whatman™ Mini-Uniprep™ syringeless filters, the compression distance X (see  FIG. 1 ) is around 10 to 20 mm; the internal diameter of a well  222  and recess  212  is approximately 12 mm. The overall height of the compressor is around 50-60 mm when compressed and has a diameter of around 50 mm at its widest point. 
         [0040]    A second version  300  of a compressor is shown in  FIG. 5 , where parts common to the compressor  200  have like reference numerals. In this version, the formations  260  and  262  are replaced with far more pronounced formations  360  and  362 , but which serve the same purpose, which is to align the top  210  and base  220  during compression. Formation  360  is a part-annular (an incomplete annulus) sleeve which extends around the axis of the compressor and has an opening  361  to accommodate the observation window  224 . Formation  262  is a complementary part-annular channel extending downwardly from the top face  252  of the base  220 . The sleeve  360  and the channel  362  are dimensioned such that the sleeve engages the channel prior to any initial compression of the syringeless filtration device  100 . Strengthening ribs  363  spaced around the sleeve  360  and running axially along the sleeve add rigidity to the sleeve to inhibit bending in use, and also increase the effective width of the sleeve to fit more snugly in the channel  362  as the sleeve slides axially in the channel in use, without requiring excess use of plastics material. As with the collar  260 , the sleeve  360  generally blocks the path for any debris if a filter device were to shatter. 
         [0041]    This second embodiment also includes four dimples  270 , only one of which is referenced, which act as final stops to prevent over compression of the filter device, and also act as final alignment members. 
         [0042]      FIG. 6  shows a third embodiment of a compressor  400  which has the same function as the first and second embodiments. The compressor  400  has a base  420 , including a well  422  into which a syringless filter  100  can be partially inserted, and a top  410 , including a recess  412  which locates over the top of the filter  100 , and is used to manually compress the filter, in the manner described above. 
         [0043]    In this embodiment the top  410  has a skirt  454 , which extends externally over sides  440  of the base  420 . The skirt includes four webs  456  which slide within complementary channels  458  in the sides of the base, to provide additional location. The skirt  454 , webs  456 , sides  440  and channels  458  are complementary formations which provide alignment of the top and base when compression takes place, thus inhibiting misalignment. 
         [0044]    When the top and base come closer together radially extending portions  452  of the webs  456  abut with an upper face  450  of the base to provide final alignment of the top and base. 
         [0045]    This embodiment is intended for use on a bench, whereby a user pushes down on the top  410  to compress a filter  100 , whilst the base  420  rests on the bench. The base  420  also includes a lower flange  480 , which provides a stability when a filter  100  is compressed on the bench. 
         [0046]    The above embodiments are illustrative of the invention and it will be understood that the invention is not limited to those embodiments. For example the term ‘base’ and lop&#39;, as well as various expressions which define orientation of the device  100  and compressor  200  are not intended to limit use of those elements in any particular orientation, but are merely representative of the orientation shown in the drawings. 
         [0047]    The term ‘syringeless filter’ is not limited to the device shown in  FIG. 1 , and other similar devices are envisaged for use with the invention. For example, also included in the definition of a syringeless filter device is a device in which the filtrate is collected externally. For example, syringeless filter devices such as the Whatman™ Autovial™ may be used. The Whatman™ Autovial™ comprises a plunger and a barrel, with the liquid sample to be filtered being initially held in the barrel. The barrel has an opening at one end through which liquid may pass via a filter membrane; during filtering, the plunger is pushed towards the filter membrane, forcing the liquid sample through the filter membrane and through the opening; the filtrate exiting the device is collected in an autosampler vial or any other appropriate container. In embodiments in which externally-collecting syringeless filtration devices are used, the containers for collecting the filtrate could be located in the holder  206 , so that a syringeless filter device engages with each of the containers. 
         [0048]    It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.