Field of the Invention The invention relates to apparatus for agitating a liquid, as well as to related methods.

Background to the Invention

Methods for agitating fluid suspensions are well known in the art, including various forms of automated stirring and/or shaking apparatus. Also known are stomachers, which blend the contents of a bag using paddles to reciprocally exert and release pressure upon a single portion of a flexible container (see e.g. Tuttiebee (1975), The Stomacher— its use for homogenization in food microbiology. International Journal of Food Science & Technology, 10: 113-122).

However, there remains a need for apparatus and methods that can quickly and uniformly agitate various liquids whilst removing contamination risks, the need for washing of vessels that come into contact with the liquids and cleaning methods and validation or reusable vessels,

Summary of the Invention

In a first aspect there is provided apparatus for agitating a liquid sample comprising: (a) an extraction pouch having walls defining a chamber in which a liquid sample is confined, the pouch comprising a pair of opposed walls, at least one of which is flexible;

(b) a frame for holding said extraction pouch; (c) an agitator assembly comprising a roller adapted to roil over an outer surface of said flexible wall of the extraction pouch and to exert a rolling pressure thereon, whereby a portion of the pouch is compressed such that part of the liquid sample is displaced and forced to flow within the extraction pouch, under and/or around the roller, so agitating it within the sample chamber; and (d) a motor operably coupled to said agitator assembly and/or to said frame for reciprocating the roller relative to the extraction pouch.

Liquid samples

Any liquid sample may be agitated according to the invention provided that at least a part of the liquid sample can be displaced and forced to flow within the extraction pouch, under and/or around the roller. Suitable liquids include homogeneous liquids (including mixtures of different liquids) and non-homogeneous liquids (including suspensions and emulsions). Liquid suspensions include suspensions of particulate solids in one or more liquid media.

Non-homogeneous liquids include flowable mixtures of immiscible fluids (such as oil and water mixtures) and partially solubilized (or insoluble) solids in a solvent (or mixture of solvents). In such cases, the solvent may be selected from polar or non-polar solvents, or may comprise a solvent system comprises polar and non-polar solvents. For example, the solvent/solvent system may comprise an aqueous or non-aqueous (e.g. organic) solvent. The liquid sample may comprise a gaseous component. In embodiments where a gaseous component is present, it may be generated during the process of agitation, for example as a product of chemical reactions taking place within the liquid sample.

Other liquid samples that may be agitated according to the invention include liquid samples comprising: (a) an environmental sample; (b) a cosmetic sample; (c) a herbal extract sample; (d) a laboratory reagent sample; (e) a food sample; (f) a nutraceutical sample; (g) a dietary supplement sample; (h) an agrochemical sample; (i) a veterinary product sample; (j) a fine chemical sample; (k) a waste sample (e.g. an environmental waste sample); (I) a tobacco sample; (m) a stimulant composition sample; (n) a paint sample; (o) a beverage sample; (p) an animal or plant tissue sample; (q) a clinical specimen; (r) a microbiological sample; (s) a homogenous suspension; (t) a non-homogeneous suspension; (u) an emulsion; (v) a solution; (w) a biological sample; and (x) an enzyme sample.

Extraction pouch The extraction pouch may take any convenient form and geometry. It may conveniently take the form of a bag comprising two opposed walls sealed around the perimeter. The pouch may further conveniently comprise a reversibiy seaiable opening, so that a liquid sample can be introduced and, following agitation, removed easily. This also facilitates the staged introduction of liquids to be agitated. In preferred embodiments, the sample preparation pouch is entirely flexible.

The flexible wails of the extraction pouch are preferably transparent or translucent, to permit visual inspection of the liquid sample. In certain embodiments, the flexible wails of the extraction pouch are formed of polyethylene or polypropylene.

The liquid sample in the pouch chamber may be of any volume, but in most embodiments it has a volume within the following ranges: 1-1000 ml; 2-1000 ml; 5-1000 mi; 10-1000 ml; 25-500 ml; 20-1000 ml; 50-1000 ml; 50-750 ml; 50-500 ml; 1-100 mi; 1-5 ml; 1-10 ml or 1- 25 ml.

Liquid agitation

The apparatus finds application in the agitation of a liquid sample for any purpose, including: the dispersion of solids in a liquid; the homogenization of a non-homogeneous fiowabie sample comprising at least two physical phases and/or at least two chemical components to form a liquid homogenate; the dissolution of one or more solutes in a solvent or solvent system; the dissolution or extraction of drug dosage forms (e.g. for subsequent analysis); the extraction of solid or liquid components from biological specimens or samples; the extraction of biological components (e.g. cells, cellular fractions, cell components, enzymes, biomolecules and/or infectious agents (e.g. bacteria, viruses and/or fungal cells) from biological specimens or samples (such as biopsy specimens and clinical samples, including human tissue samples); the mixing of reagents for biochemical assay and/or chemical synthesis; the mixing of ingredients in food and beverage preparation or analysis; in brewing; in the mixing of samples and/or reagents in quality control processes in the pharmaceutical industry.

Thus, the agitation provided by the invention finds application in the distribution and/or suspension and/or dissolution of solids in an extraction fluid. Thus, in certain

embodiments, the extraction pouch contains one or more solid dosage forms and an extraction fluid therefor, for example being a solvent, and the agitation results in

homogenization and/or distribution and/or suspension and/or dissolution of the dosage form in the extraction fluid. Any solid dosage form may be dissolved and/or suspended in an extraction liquid according to the invention, including but not limited to pharmaceutical solid dosage forms (including solid oral dosage forms, for example pills, capsules, lozenges and tablets), dietary supplement dosage forms, pelleted feedstuffs, environmental samples, cosmetics, herbal extracts, pesticides, fertilizers, laboratory reagents and indeed to any composition which is in a solid unit dose form. in certain embodiments, the solid dosage form is a pharmaceutical solid dose form. Here, the pharmaceutical solid dose form may be a slow-release, sustained release, prolonged release, hard-compacted or tamper-proof dosage form. In such embodiments, the solid dosage form is at least partially crushed or pulverized prior to agitation in the apparatus of the invention.

Agitating assembly The agitating assembly of the invention comprises a reciprocating roller adapted to roll over an outer surface of said flexible wall of the extraction pouch and to exert a roiling pressure thereon, whereby a portion of the pouch is compressed such that part of the liquid sample is displaced and forced to flow within the extraction pouch, under and/or around the compressed portion of the extraction pouch under the roller, so agitating it within the sample chamber.

Fixed roiiers

The roller for use in the agitating assembly of the invention may be a fixed roller. As used herein, the term "fixed roller" defines a roller which is adapted to roil over the outer surface of the extraction pouch at a constant rolling height. As used herein, the term "rolling height" applies in relation to all rollers for use according to the invention (including fixed, lifting, nip, gapped and profiled roiiers) and defines the distance between the opposed wails of the extraction pouch when under rolling pressure. In embodiments where the frame further comprises a support surface for supporting the wall opposed to the flexible wall of the extraction pouch subject to rolling pressure, the roiling height may also define the distance between the support surface and the roller. The roiling height of a fixed roller may be adjustable by the user. For example, the apparatus of the invention may comprise a roller height adjustment means for adjusting the rolling height of a fixed roller. Such rollers are herein referred to as adjustable rollers.

Lifting rollers

The roller for use in the agitating assembly of the invention may be a lifting roller. As used herein, the term lifting roller" defines a roller which is adapted to roll over the outer surface of the extraction pouch at a rolling height which is not constant. As previously explained, the rolling height defines the distance between the opposed walls of the extraction pouch when under roiling pressure, and in embodiments where the frame further comprises a support surface for supporting the wail opposed to the flexible wall of the extraction pouch subject to rolling pressure, the rolling height may also define the distance between the support surface and the lifting roller.

Lifting rollers therefore include rollers adapted to roll over the outer surface of the extraction pouch at a rolling height which varies continuously as the roller rolls over the outer surface of the flexible wail of the extraction pouch. Lifting rollers therefore include rollers adapted to roll over the outer surface of the extraction pouch at a rolling height which is determined (at least in part) by the hydrostatic pressure of the liquid sample within the compressed portion of the extraction pouch under the roller. Lifting rollers also include rollers adapted to roll over the outer surface of the extraction pouch at a rolling height which is determined (at least in part) by the presence of solids within the liquid sample. For example, lifting rollers include rollers adapted to lift when passing over solid particles or highly viscous components within the liquid sample. Thus, both fixed and lifting rollers for use in the agitating assembly of the invention may function as nip and gapped rollers, as described below. Moreover, in some embodiments a lifting roller may function as both a nip and a gapped roller when in use, depending on the roiling height, since the rolling height in such embodiments (as explained above) may vary as the roller roils over the outer surface of the flexible wail of the extraction pouch (being determined inter aiia by the hydrostatic pressure of the liquid sample within the

compressed portion of the extraction pouch under the roller and/or the presence of solid or highly viscous components within the sample). Nip roiiers in certain embodiments, the agitating assembly of the invention comprises a nip roller. As used herein, the term "nip roller" defines a roller adapted to roll over the outer surface of the extraction pouch at a rolling height at which the opposed walls of the extraction pouch are brought into contact when under rolling pressure. Thus, a nip roller is configured such that it brings the inner surface of said flexible wail into contact with the inner surface of the opposed wall of the extraction pouch. The rolling pressure of a nip roller therefore excludes all liquid from the compressed portion of the extraction pouch under the roller, so that part of the liquid sample is displaced and forced to flow away (for example around) the compressed portion of the extraction pouch under the roller.

Gapped roi!ers in certain embodiments, the roller is a gapped roller. As used herein, the term "gapped roller" defines a roller adapted to roll over the outer surface of the extraction pouch at a rolling height at which the opposed walls of the extraction pouch are not brought into contact when under rolling pressure, but remain spaced apart by a gap which permits the liquid sample to flow in the compressed portion of the extraction pouch under the roller. The roiling pressure of a gapped roller is therefore insufficient to bring the flexible wall of the extraction pouch into contact with the opposed wall. A gapped roller is therefore configured such that it does not bring the inner surface of said flexible wall into contact with the inner surface of the opposed wall (so that a gap between the walls and under the roller is maintained). A gapped roller therefore permits a flow of liquid sample between the compressed walls of the portion of the pouch under the roller, so that part of the liquid sample may be displaced and forced to flow both under and around the compressed portion of the extraction pouch under the roller.

The use of such a gapped roller may reduce or eliminate bag fatigue and/or failure and may also find particular application when the liquid is (at least prior to agitation) non- homogeneous, containing solids (for example in particulate form).

Agitating assemblies comprising a gapped roller may further comprise means for generating a pressure on the portion of the outer surface of said flexible wail by the roller. Suitable means for generating pressure include those comprising a weight, a coiled spring, a lever spring, gas spring, hydraulic strut, solenoid, servo-motor or stepper-motor.

Profiled rollers The roller for use in the agitating assembly of the invention may be a profiled roller. As used herein, the term "profiled roller" defines a roller comprising a tread adapted to roil over the outer surface of the extraction pouch, which roller tread comprises grooves and/or or ribs (i.e. the roller comprises a grooved and/or ribbed cylindrical portion). In such embodiments, the cylinder may comprise circumferential and/or longitudinal grooves or ribs.

Multiple rollers

The agitating assembly of the invention may comprise a plurality of rollers, in such embodiments, the rollers may comprise a combination of:

(a) two or more fixed rollers; and/or

(b) two or more lifting rollers; and/or

(c) two or more gapped rollers; and/or

(d) two or more nip rollers.

In such embodiments, the rollers may comprise a combination of at least one fixed roller and at least one lifting roller. In embodiments where the rollers comprise a combination of two or more fixed rollers, one or more of the rollers may be adjustable rollers, and may be independently adjustable.

The rollers may comprise a combination of at least one nip roller and at least one gapped roller. In such embodiments, the nip and/or gapped roller may be fixed or lifting.

In some embodiments, the agitating assembly of the invention may comprise a plurality of lifting rollers, for example a plurality of gapped, lifting rollers. In a preferred embodiment, the agitating assembly comprises a plurality of rollers (for example, gapped and/or lifting rollers) spaced apart on a common spindle. Here, the rollers may comprise 2-8, 2-8 or 2-4 rollers spaced apart on a common spindle.

In such embodiments, each roller may be a nip roller, a gapped roller or a combination of nip and gapped rollers, in each case, the rollers may be fixed or lifting. In such embodiments, the rollers permits a flow of liquid sample between the rollers in the uncompressed portions of the pouch under the spaces between the rollers, so that part of the liquid sample may be displaced and forced to flow between them.

Motor

The apparatus of the invention comprises a motor operabiy coupled to said agitator assembly and/or to said frame for reciprocating the roller relative to the extraction pouch.

Any form of motor may be employed provided that sufficient force is generated to move the pouch relative to the roller such that it rolls over an outer surface of said flexible wall of the extraction pouch and exerts a rolling pressure thereon. The motor may further comprise a programmable controller for actuating movement of the roller, and may permit user-controlled values for roller speed, roller pressure and/or reciprocations per minute. For example, the roller may reciprocate at a rate of: 1-120 strokes per minute, for example 2-60 strokes per minute. The reciprocation may be continuous or pulsed. In preferred embodiments, the roller operation parameters are selected by the operator by reference inter alia to the volume of the liquid sample, the volume of the liquid sample chamber, the nature of the liquid sample, its viscosity and the effects of agitation on the foregoing characteristics. trame

The apparatus of the invention comprises a frame for holding said extraction pouch. Any suitable frame may be employed, provided that it allows the extraction pouch to be moved relative to the rollers of the agitating assembly. in preferred embodiments, the frame further comprises retaining means which immobilizes the entire periphery of the pouch within the frame.

In another aspect, the invention provides a method for agitating a liquid sample comprising the steps of:

(a) sealing the liquid sample in a extraction pouch comprising opposed walls, at least one of which is flexible, such that the liquid sample is contained therein; and

(b) exerting pressure on a portion of the outer surface of said flexible wail of the extraction pouch with an agitator assembly comprising a reciprocating roller adapted to roll over an outer surface of said flexible wall of the extraction pouch and to exert a rolling pressure thereon, whereby a portion of the pouch is compressed such that part of the liquid sample is displaced and forced to flow within the extraction pouch, under and/or around the roller, so agitating it within the sample chamber. in a further aspect, the invention contemplates the use of the apparatus of the invention for agitating a liquid sample, for example according to a method as defined above. Such uses include methods for homogenizing liquids of all kinds. Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 is a perspective schematic view of apparatus according to the invention.

The apparatus 10 comprises an extraction pouch having flexible walls 12 containing a liquid sample (not shown) mounted on a frame 14 by peripheral clamps 16. An agitator assembly comprising inner and outer rollers (18 and 20, respectively) mounted, in a spaced apart configuration, on a common spindle 22 and operably coupled to a motor (not shown) are positioned to roll over an outer surface of said flexible wall of the extraction pouch in the directions indicated by the arrows when the spindle 22 is reciprocated by the motor. Outer rollers 20 are of smaller radius than the inner rollers, and so serve as gapped rollers. The inner rollers 18 are configured to bear down onto the surface of the pouch with a pressure provided by coil springs (not shown), and therefore act as lifting rollers, serving as both gapped and nip rollers (as explained below).

Referring to Figure 1 , extraction pouch 12 is loaded onto the frame 14 by tightening the clamps 16 such that three sides of the pouch 12 are securely fixed onto the frame 14. The resealabie opening (not shown) in the extraction pouch 12 is then opened and the liquid sample (not shown) is introduced into the chamber of the pouch via the opening. The opening is then resealed. Activation of the motor (not shown) causes reciprocation of the spindle 22, so causing the rollers 18 and 20 to roll over outer surfaces of the flexible walls of the extraction pouch in the directions indicated by the arrows. Portions of the pouch underlying the rollers are thereby compressed, so that portions of the liquid sample confined therein are displaced and forced to flow: (a) under and around the rollers 20; and (b) around the rollers 18 (and also under them, when the hydrostatic pressure of the compressed portion of the fluid sample under the rollers exceeds the pressure generated by the coil springs).

Repeated reciprocation of the spindle therefore induces rapid flow of the bulk liquid sample both under and between the rollers (18, 20), so vigorously agitating the liquid sample within the sample chamber. The foregoing description details presently preferred embodiments of the present invention which are therefore to be considered in all respects as illustrative and not restrictive.

Those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, many equivalents, modifications and variations to the specific

embodiments of the invention described specifically herein. Such equivalents,

modifications and variations are intended to be (or are) encompassed in the scope of the following claims.