ZA200301675B

ZA200301675B - Sample preparation system.

Info

Publication number: ZA200301675B
Application number: ZA200301675A
Authority: ZA
Inventors: Brian Taylor; Ian Mckellar; Gregory Dickinson
Original assignee: Strategic Technology Ltd
Priority date: 2000-07-31
Filing date: 2003-02-28
Publication date: 2004-03-09
Also published as: WO2002010773A1; AU2001284555A1

Description

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TITLE: SAMPLE PREPARATION SYSTEM

Technical Field

N This invention relates generally to automated systems for laboratory sample preparation and testing, and o 5 particularly to systems for soil sample preparation and testing.

The invention also relates to gripper-nozzles for use with such systems, to automated sample dispensers for accurate volume measurement of granular material, to devices for mixing a large number of separate vessels in an automated sample preparation system and to apparatus for the automated filtering of sample mixtures.

BACKGROUND ART

Sample processing for soil tests, must often be performed on a large number of samples. Further, it is often necessary to perform different tests on each of the many samples. Each test requires placing a sample in a container and the mixing of one or more reagents with a sample and performing an analysis such as a pH, sulphur or phosphate measurement. Preparing multiple samples for such tests manually is very time consuming and subject to error.

More recently, robotic systems have been developed to automatically withdraw sample liquid from sample containers and reagent from reagent containers and to mix the two in test cells for analysis. The sample containers and test cells may be positioned in circular arrays on turntables. One or more probes on robot arms carry sample liquid to the test cells and reagent from reagent containers to the test cell.

While these robotic systems have provided significant improvements, in relation to the processing of granular sample material such as soils, there remains a need for an improved automated sample dispenser capable of accurate automated volume measurement of granular sample material. There is also a need for an improved system for mixing a large number of separate measures of sample material and reagents, for a device for the automated filtering of the sample mixtures and for improved gripper- nozzles for use with such systems.

US Patent No. 4747316 describes a probe-gripper comprising a rigid tube section surrounded by an elastomeric inflatable bladder which is entered into the mouth of a container and pressurised to grip and seal the container mouth. The disadvantages of this design include the lack of a means for accurately locating the device with regard to the rim of the container with good stability, as well as its complexity and consequent high manufacturing costs. “ Further aspects and advantages of the present invention will become apparent from the ensuing ~ description, which is given by way of example only. ‘

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DISCLOSURE OF INVENTION

According to one aspect of the present invention there is provided a sample preparation system for automatically processing multiple samples, the system including: locating means to locate a plurality of containers for separately storing samples of granular 3 5 material; © a dispenser for dispensing a measured volume of the sample material from a container into . mixing cells; a liquid reagent dispenser for metering reagent into the mixing cells; a filter station where the contents of a mixing cell are filtered to produce a filtrate; a transport system for transporting mixing cells to and from the filter station; and a distributor for receiving the filtrate from each mixing cell and distributing each measure of filtrate into a receptacle.

According to another aspect of the present invention there is provided a sample preparation system substantially as described above which is controlled by a central controller wherein each container has identification indicia; and the system further includes an indicia reader for providing the container . identification indicia to the central controller, and wherein the controller has memory storage and a data input element for inputting instructions for processing of the contents of each container according to the container identification indicia, the processing instructions being stored in memory.

Preferably the locating means locates a rack for holding containers. Optionally, sensors may be provided to indicate the presence of a container in each position on a rack.

According to another aspect of the present invention there is provided a sample preparation system substantially as described above wherein the dispenser is fixed to a robot having a gripper-nozzle which engages one container at a time with the dispenser, the dispenser including means to invert the gripped container to discharge the granular material into a cavity in a sliding block, which fills with material in a first position, and which dispenses material in a second position.

According to another aspect of the present invention there is provided .a sample preparation system substantially as described above wherein the dispenser includes: a horizontal base plate with a middle portion formed with an opening to receive granular material from the container; a sliding block mounted on a bottom side of the base plate, the sliding block having a granular material retaining cavity with substantially vertical walls and an outlet aperture that is aligned with the . opening in the base plate in the first position; a plug valve fixed to the sliding block for opening and closing the outlet aperture; and tn power actuated means to slide the sliding block to the second position whereby, granular material in the ’ sliding block is discharged from the outlet aperture into mixing cell provided below the base plate when 40 the sliding block is moved to the second position and the plug valve is opened.

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According to another aspect of the present invention there is provided a sample preparation system substantially as described above wherein the first and second positions are at the opposite ends of a linear reciprocating motion of the sliding block. [3 5

According to another aspect of the present invention there is provided a sample preparation system , substantially as described above wherein the granular material is soil, having a predetermined moisture content and particle size distribution.

The operation of the dispenser is controlled by the controller, which may for example instruct multiple measures of sample material to be dispensed. Alternatively, the number and volume of the cavities dispensed from may be selected by the controller. In an alternative embodiment, instead of indexing the robot transversely to fill each mixing cell, a block may be provided with multiple cavities. In this embodiment the number and spacing of cavities corresponds to the number of mixing cells per transverse row and the spacing between the centres of adjacent containers in the row.

According to another aspect of the present invention there is provided a sample preparation system substantially as described above wherein the gripper-nozzle includes: a flexible sleeve surrounding a frustroconical nozzle having a central flow passageway which terminates in a nozzle opening, the sleeve being inflatable by pressurised fluid to cause it to expand and contract between gripping and releasing positions respectively, and a connection for passing pressurised fluid to the interior of the sleeve, characterised in that the nozzle includes an abutment member fixed about the external periphery of the nozzle and adapted to abut against a rim of the container.

According to another aspect of the present invention there is provided a sample preparation system substantially as described above wherein the sleeve is adapted to be inserted into an opening of a container and the sleeve is made from elastomeric material.

According to another aspect of the present invention there is provided a sample preparation system substantially as described above wherein the mouth of the container includes a necked portion and the inflated sleeve engages below the necked portion.

According to another aspect of the present invention there is provided a sample preparation system substantially as described above wherein each mixing cell has a cup with substantially cylindrical walls, the axis of the cup in being inclined at an acute angle to the vertical and about which axis the cup is ¢ rotated. ' According to another aspect of the present invention there is provided a sample preparation system 40 substantially as described above wherein the transport system is a chain conveyor on which o mixing cells are mounted, aligned in transverse rows, each cup being mounted in a rotatable holder and characterised in that each holder in a transverse row is driven for rotation by an endless flexible belt.

According to another aspect of the present invention there is provided a sample preparation system ; 5 substantially as described above wherein the belt is driven by a rotating shaft which extends for substantially the full length of the horizontal travel of the conveyor, the belt sliding longitudinally with

N respect to the shaft.

According to another aspect of the present invention there is provided a sample preparation system substantially as described above wherein at the end of the mixing cycle a reduction in the diameter of the shaft reduces the tension in the belt, stopping the rotation of the mixing cells and allowing the contents to settle.

According to another aspect of the present invention there is provided a sample preparation system substantially as described above wherein the filter station includes: a drive roller to advance a continuous length of filter paper between an upper and lower filter block and a switch to detect to presence of paper to stop the drive roller; releasable clamping means to clamp and seal the filter paper in a flow passage between the upper and lower blocks; a blade for separating the clamped section of filter paper from the continuous length; means for passing the contents of a mixing cell to the upper filter block; means for collecting the filtrate from the lower filter block; and . means for ejecting the used section of filter paper from between the filter blocks.

According to another aspect of the present invention there is provided a sample preparation system substantially as described above wherein the filtrate is drawn through the filter blocks by a vacuum and upon completion of a filtration cycle the filter blocks are washed with water.

According to another aspect of the present invention there is provided a sample preparation system substantially as described above wherein the blade is operated by a reciprocating ram.

According to another aspect of the present invention there is provided a sample preparation system substantially as described above wherein the means for ejecting the used section of filter paper from between the filter blocks includes: a traction roller mounted below the filter paper; a first air jet directed against the paper to separate it from one of the lower filter block;

N a second air jet directed against the paper to separate it from the upper filter block, the second ’ jet also acting to increase the normal load on the traction roller to assist in driving the paper from . between the filter blocks. 40 According to another aspect of the present invention there is provided A method of preparing a

¥ sample of granular material, including the steps: providing a sample preparation system substantially as described above; providing a rack containing a plurality of open top containers; gripping a first container and removing it from the rack, inverting same and dispensing a ? 5 measured volume of the granular material into a mixing cell; metering a liquid reagent into the mixing cell; s transporting the mixing cell to the filter station; and : drawing a filtrate from the filter station. 10 According to another aspect of the present invention there is provided a dispenser for dispensing a measured volume of granular material, including a container having an opening to discharge the granular material into a cavity in a sliding block, which fills with material in a first position, and which dispenses material in a second position. 15 According to another aspect of the present invention there is provided A method of dispensing a measured volume of granular material, including the steps: providing a dispenser substantially as described above; placing the sliding block in the said first position and filling the said cavity; and sliding the said block to the said second position whereupon the material drops from the cavity. 20

According to another aspect of the present invention there is provided a gripper-nozzle for an automated sample preparation system including: a flexible sleeve surrounding a frustroconical nozzle having a central flow passageway which terminates in a nozzle opening, the sleeve being inflatable by pressurised fluid to cause it to expand and 25 contract between gripping and releasing positions respectively, and a connection for passing pressurised fluid to the interior of the sleeve, characterised in that the said nozzle includes an abutment member fixed about the external periphery of the nozzle and adapted “ to abut against a rim of the container. 30 According to another aspect of the present invention there is provided A method of gripping a container, including the steps: providing a gripper-nozzle substantially as described above; inserting an end of the nozzle into the mouth of the container until the abutment member abuts against the rim of the container mouth; and 35 inflating the said sleeve by means of pressurised fluid to cause it to expand to a gripping . position :

According to another aspect of the present invention there is provided a mixing apparatus for an ) automated sample preparation system including a mixing cell having a cup withsubstantially cylindrical j WO 02/10773 PCT/NZ01/00156 walls, the axis of the cup in being inclined at an acute angle to the vertical and about which axis the cup is rotated.

According to another aspect of the present invention there is provided substantially as described above : 5

According to another aspect of the present invention there is provided an automated filter station 3 including: a drive roller to advance a continuous length of filter paper between an upper and lower filter block and a switch to detect to presence of paper to stop the drive roller; releasable clamping means to clamp and seal the filter paper in a flow passage between the said upper and lower blocks; a blade for separating the clamped section of filter paper from the continuous length; means for passing the contents of a mixing cell to the upper filter block; means for collecting the filtrate from the lower filter block; and means for ejecting the used section of filter paper from between the filter blocks.

According to another aspect of the present invention there is provided a method of filtering a mixture, including the steps: providing a filter station substantially as described above; advancing paper from the continuous length of filter paper between the upper and lower filter blocks; detecting the presence of paper in the correct position and stopping the drive roller; clamping and sealing the filter paper in the flow passage between the said upper and lower blocks; separating the clamped section of filter paper from the continuous length; passing the said mixture to the upper filter block; collecting the filtrate from the lower filter block; and ejecting the used section of filter paper from between the filter blocks.

It will be appreciated that each of the components of the system - the gripper-nozzle, the granular material dispenser, the mixing cell device and the automated filter station, can each be incorporated into different systems, whether for batch sample preparation or for other purposes. Whilst the above system has been described with reference to the preparing test samples of granular material, it is most particularly suited for the preparation and testing of soil samples which are routinely tested in batches.

The system provides significant improvements over prior-art systems. ’ BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is a partly cut-away side elevation of a preferred embodiment of the sample preparation system ’ of the present invention; 40 Figure 2 is an end elevation of the system of Fig. 1;

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Figure 3 is a sectional elevation of gripper-nozzle of the present invention engaged with a container;

Figure 4 is a sectional elevation of a sample dispenser of the present invention in a dispensing position;

Figure 5 is an end elevation of a mixing cell of the present invention; and

Figure 6 is a sectional elevation of a filter station of the present invention. : 5

BEST MODES FOR CARRYING OUT THE INVENTION

, Fig. 1 is a side elevation of a sample preparation system of the present invention, showing the processing of soil samples for the required tests, from left to right. The system includes a continuous chain type conveyor 20 which carries a rectangular array of inclined mixing cells 21 between a filling station 10 and an emptying station 30. .

At station 10 a rack 3 of open top containers 2 holding granular soil samples is provided. A robot 1 having a gripper-nozzle 4 (described in more detail with respect to Fig. 3) retrieves a container 2 from the rack 3 (the robot is designated as 1' in this position and shown in phantom outline). A dispenser 101 mounted on the robot 1 then dispenses a measured volume of soil sample material from the container 2 into a mixing cell 21, which is substantially upright at this point. A reagent dispenser (not shown) meters fluid reagents into each of the mixing cells 21. The conveyor 20 moves in a stepwise mode, indexing forward in direction F generally in steps corresponding to the longitudinal pitch of the mixing cells 21.

At station 30 the mixing cells 21 are inverted as they pass to the underside of the conveyor 20, thereby emptying the mixture into a collector 31, the mixture then passes to a filter station 40. From the filter station 40 the filtrate is recovered and distributed to test tubes (not shown) for subsequent analysis.

The mixing cells 21 are cleaned at a wash station (not shown) while they are inverted on the return to station 10 on the lower side of the conveyor 20. Each filter station 40 is also cleaned between receiving samples to avoid cross contamination.

As shown in Fig. 1, the station 10 includes a table 80 having placement locations for placement of the rack 3 for holding containers 2 that hold material be processed and containers whose material has been processed. The table 80 is supported on a column and beam framework 83 which also supports the other components and defines the periphery of the system. A longitudinal track 81 and transverse tracks 82 are provided for the horizontal movement of robot 1 and from which the robot 1 is suspended. The rack 3 is manually loaded onto the table 80 and the containers 2 are removed one by one by the robot 1 from therack 3 for processing.

As illustrated in Fig. 2, in the preferred embodiment of the invention there are four mixing cells 21 aligned across the conveyor 20 in longitudinal rows W, X,Y, Z. The system is adapted to be used with ’ samples (not shown), which need to undergo identical processing, being placed in mixing cells 21 in 40 one (or more) of the longitudinal rows W, X,Y, Z. A probe 33 extends on an arm 32 into each

RE oo oo oo mixing cell 21 in row W for taking a pH measurement. The arm 32 is translatable vertically to position the tip of the probe 33 within the selected mixing cell 33. The contents of the mixing cells 21 in row W are emptied to waste, whereas collectors 31 are provided for each of rows X, Y, Z directing the sample material to separate filter stations 40. > 5

The containers 2 each have an indicia, preferably a barcode (not shown) to identify the soil sample held . therein. The containers 2 are manually racked in ten by one arrays and each position in the rack 3 is individually addressable by the robot 1. The system operates under the control of a central computer controller (not shown) which determines the operations to be performed on the contents of each 10 container 2 in accordance with instructions input by the operator. An indicia reader (not shown) provides the container 2 identification to the controller, which controls the system to prepare the samples or perform the tests required.

Referring to Figs 3 and 4, the gripper-nozzle 4 includes an elastomeric inflatable sleeve 5 for gripping a 15 container 2. The sleeve 5 covers a frustroconical nozzle 9 with a flow passageway 6 having an open bottom 8 which is small enough to enter into the open end of the container 2. The sleeve 5 is joined to the nozzle 9 to form an air chamber 10 having a connection 11 to a pneumatic system controlling the inflation thereof. A fixture 11 is provided at the top 7 of the sleeve 5 and allows the gripper-nozzle 4 to be engaged by a robotic arm 12 for moving the container 2 and for the transfer of product through the 20 passageway 6.

The gripper-nozzle 4 is inserted into the container 2 (see also robot position 1', Fig. 1). When the sleeve has fully entered into the open mouth of the container 2, an abutment flange 7 abuts against the rim of the container 2 for accurate location. Pressurised air is then caused to flow through the connection 11 into the air chamber 10, pressurising it and causing the sleeve 5 to bulge outwardly, gripping the interior of the container 2 (the sleeve is designated as 5' in this position and shown in phantom outline). The air chamber 10 is formed below a neck portion 14 in the mouth of the container 2 which provides good stability in gripping the container 2. The sleeve 5 also seals around the opening of the container 2, allowing flowable material to be passed from the gripper-nozzle 4 into the container 2 (or vice versa) without significant "dead space” (space which cannot be emptied when the container 2 is inverted).

Next, the robot arm 12 raises the gripper-nozzle 4 and, keeping it upright, lifts the funnel 13 to engage and seal against an abutment 28 on the head 25. The head 25 is then rotated about the axis H, together with the gripper-nozzle 4 and the container 2, to the inverted dispensing position.

Advantageously, the gripper-nozzle 4 may be used to allow the robot 1 to engage other objects (not shown) not necessarily having openings but having, for example, a compatible fixture with at least a pair of opposed edges. : ° Soil sample material from the inverted container 2 is discharged into the soil sample dispenser 101 (Fig 40 4) mounted on the head 25 of the robot 1 above an open-mouthed mixing cell 21. Soil sample material is discharged into the mixing cell 21 through the passageway 6 and funnel 13 into a cavity 16 in a reciprocating block 17 of the dispenser 101, by means of gravity. The cavity 16 has parallel substantially vertical walls and an outlet aperture 18 which is closable by a pivoted plug valve 19. A predetermined amount of soil sample material from the container 2 is discharged through the outlet 18 ’ 5 with each cycle of the reciprocating block 17 and plug valve 19. The reciprocating movement of the block 17 and the movement of the conveyor 20 are synchronised to co-ordinate the discharge of soil . sample material into the centre of each container mouth. The robot 1 traverses across each lateral line of mixing cells 21 between steps in the conveyor movement to distribute a measured sample volume as instructed by the controller.

The block 17 is shown in Fig. 4 in a discharge position at one end of its travel, with the valve 19 open and retracted approximately 90° from the closed position. The axis of the cavity 16, together with the valve 19, reciprocates horizontally between the axis D of the container 2 (the filling position) and the axis C of the mixing cells 21 (discharge position).

In the filling position (not shown), in order to assist flow of the granular sample and to fill voids in the cavity 16, the head is "tapped" to provide agitation, thereby simulating manual tapping. This "tapping" is performed by a reciprocating pneumatic ram (not shown) which moves a weight up and down. The sliding faces of the block 17 and the head 25 are finished to high level in order to ensure accuracy and to avoid material being trapped therebetween.

In the discharge position the plug valve 19 is moved from the closed position (shown in phantom outline as 19") to the open position and again the head 25 is "tapped" to assist the complete evacuation of the cavity 16. When the predetermined mixing cells 21 have been filled by the distributor 101 the head is turned upright then "tapped" to assist in returning sample material to the container 2. The container 2 is then replaced in the rack 3 whereupon the flexible sleeve 5 is depressurised returning to its original position, allowing the container 2 to be released. :

The granular sample is dried and comminuted, producing a readily flowable material. The sample flow through the dispenser 101 is not significantly affected by humidity or electrostatic effectsand produces good volume accuracy and repeatability. Sample material is also measured by the dispenser 101 onto scales (not shown). As well as for weight determination, this measurement is used for control and calibration checking, with the scale being connected to the controller. The block 17 is readily replaceable to allow different volumes of sample material to be transferred in the same operation.

At station 10 liquid reagents are metered into the mixing cells 21 under instruction from the controller. } In the embodiment illustrated four different reagents are used, one in each of the rows W, X, Y, Z (Fig. 2) and separate dispensers (not shown) of a known type meter each of the reagents. ’ Figs 4, 5 and 6 show the operation of the mixing cells 21. Each mixing cell 21 includes a cup 22 having 40 substantially cylindrical walls. The cup 22 is fixed to a holder 23 supported upon bearings (not shown) for rotation about the cup axis C which is inclined at an angle 0 to the conveyor 20 (or to the vertical during the horizontal movement of the mixing cells 21). The base 23 is driven by drive shaft 26 through a flexible belt 24 guided by a pair of idler pulleys 25. The shaft 26 extends the length of the conveyor 20, being supported upon bearings (not shown) at either end of the conveyor 20 and driven by ’ 5 a motor/reduction box 27 (see Fig. 1). As will be appreciated, rotation of the shaft 26 frictionally engages the belt 24 to rotate the mixing cells 21. The belt 24, however, is able to slide longitudinally

X with respect to the shaft 26 as the conveyor 20 moves forward. Optionally, the mixing cells 21 may be continuously or intermittently rotated or oscillated.

At station 30 the rotation of the mixing cells 21 is stopped, allowing the contents to settle: Settling before filtration reduces the blinding of the filter paper and shortens filtering time. A reduction 29 in the diameter of the shaft 26 reduces the tension in the belt 24, and the angular extent of wrap. To further reduce friction a plastic sleeve (not shown) is fitted over the terminal end 37 if the shaft 26, allowing it to rotate independently of the belt 24.

The filter station 40 located at one of the end of and below the conveyor 20 (Fig. 1). The filter station 40 is mounted on a parallel arm linkage 84 allowing it to be swung out for better access. Referring now to

Figure 6, the automated filter station 40 filters each sample/reagent mixture emptied from the mixing cell 21 through a section of filter paper 41 and passes the filtrate to a distributor (not shown). Filter paper 41 is taken continuously from a roll 42, it is nipped between two drive rollers 43, 44 which direct it past a blade 45 into the housing 46.

As three filter stations 40 are provided, it will be appreciated that the elements thereof may be connected (or common) for simultaneous operation. For example, the drive rollers 43, 44 extend transversely across the machine between the three filter stations 40 and drive each of the three separate rolls 42 of paper. Clutches (not shown) are provided in order that the filter paper rolls may be driven independently.

A switch (not shown) determines when the filter paper 41 is in position and stops the drive rollers (43, 44). Next, clamping rams (not shown) raise the lower filter block 48 to clamp together and seal the filter paper 41 between the upper and lower filter blocks 47 and 48. A reciprocating blade 45 is advanced through the paper 41 (to the position 45") to separate the section of filter paper 41 to be used thereby preventing the liquid reagent wicking through to the unused section. The sample/reagent mixture is drawn by vacuum from the collector 31, through the upper block 47, solid particle material is trapped by the filter paper 41 and the filtrate drops to outlet 49 at the base of the lower block 48 into a . flexible conduit 50 and thence to the distributor (not shown). The filter paper 41 is removed after the two sections of the filter block 47, 48 have been unclamped when the filtration has been completed. The

X used section of paper 41 is removed by the actuation of a traction roller 52, assisted by the action of two air jets 53, 54 which ensure the paper 41 separates from the lower and upper filter blocks 47 and 48 40 respectively. The jet 54 is directed down upon the paper and also acts to increase the normal load on the roller 52 to assist with traction in driving the paper forward toward the door 55, after which it drops to the floor of the housing 46. The blade 45 is then retracted.

Before again actuating the drive rollers 43, 44 to advance the paper 41 the filter block 47, 48 is cleaned, i 5 firstly it is rinsed with tap water and then demineralised water and is then dried by compressed air (not shown). To assist drying, the lower filter block 48 is reciprocated. The amount of water that can

R remain on the collector 31 the dimensions of the collector 31 are kept to a minimum. To ensure removal of all water before the sample filtrate is collected, a small rinse portion of the contents of the mixing cells 21 is first drawn through the collector 31 and the filter paper 41 and then disposed of. This is performed by moving the conveyor 20 forward by a small increment to control the decanting of this rinse portion. The raised blade also acts as a water barrier during the washing process.

The output of the system, for the rows X, Y, Z is an array of test tubes (not shown), each containing the filtrate from a mixing cell 21. The test tubes are held in a rack (not shown) each position in which is addressable by a distributor robot (not shown) which meters a volume of filtrate into each test tube. The output of the system for the row W, as described above, is a pH measurement obtained from the probe 32 and recorded by the computer controller.

Other tests can be conducted on the soil samples automatically in accordance with instructions programmed into the computer controller or manually.

It will further be appreciated that each of the subsidiary components of the system can be used separately as component of different systems, whether for batch sample preparation or for other purposes.

Whilst the above system has been described with reference to the testing of soil samples, it will be appreciated that any granular material that needs to be routinely tested in batches, can be tested using this system.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.

Claims

A} THE CLAIMS DEFINING THE INVENTION ARE:

1. A sample preparation system for automatically processing multiple samples, the system including: locating means to locate a plurality of containers for separately storing samples of granular material; K 5 a dispenser for dispensing a measured volume of the said sample material from a container into mixing cells; : s a liquid reagent dispenser for metering reagent into the mixing cells; a filter station where the contents of a mixing cell are filtered to produce a filtrate; a transport system for transporting mixing cells to and from the filter station; and a distributor for receiving the filtrate from each mixing cell and distributing each measure of filtrate into a receptacle.

2. A sample preparation system as claimed in claim 1 controlled by a central controller wherein each container has identification indicia; and the system further includes an indicia reader for providing the container identification indicia to the central controller, and wherein the controller has memory storage and a data input element for inputting instructions for processing of the contents of each container according to the container identification indicia, the processing instructions being stored in memory.

3. A sample preparation system as claimed in claim 1 or claim 2 wherein the dispenser is fixed to a robot having a gripper-nozzle which engages one container at a time with the dispenser, the dispenser including means to invert the gripped container to discharge the granular material into a cavity in a "sliding block, which fills with material in a first position, and which dispenses material in a second position.

4. A sample preparation system as claimed in claim 3 wherein the dispenser includes: a horizontal base plate with a middle portion formed with an opening to receive granular material from the container; a sliding block mounted on a bottom side of said base plate, said sliding block having a granular material retaining cavity with substantially vertical walls and an outlet aperture that is aligned with said opening in said base plate in said first position; a plug valve fixed to the said sliding block for opening and closing the said outlet aperture; and power actuated means to slide the sliding block to the said second position whereby, granular material in said sliding block is discharged from said outlet aperture into mixing cell provided below said base plate when said sliding block is moved to said second position and the said plug valve is opened.

5. A sample preparation system as claimed in claim 3 or claim 4 wherein the said first and second positions are at the opposite ends of a linear reciprocating motion of the sliding block.

6. A sample preparation system as claimed in any one of claims 3 to 5 wherein the granular material is 40 soil, having a predetermined moisture content and particle size distribution.

7. A sample preparation system as claimed in any one of claims 3 to 6 wherein the gripper-nozzle includes: a flexible sleeve surrounding a frustroconical nozzle having a central flow passageway which v 5 terminates in anozzle opening, the sleeve being inflatable by pressurised fluid to cause it to expand and contract between gripping and releasing positions respectively, and , a connection for passing pressurised fluid to the interior of the sleeve, characterised in that the said nozzle includes an abutment member 7 fixed about the external periphery of the nozzle and adapted to abut against a rim of the container.

8. A sample preparation system as claimed in claim 7 wherein the said sleeve is adapted to be inserted into an opening of a container and the sleeve is made from elastomeric material.

9. A sample preparation system as claimed in claim 6 or claim 7 wherein the mouth of the container includes a necked portion and the inflated sleeve engages below the necked portion. ~~

10. A sample preparation system as claimed in any one of claims 1 to 9 wherein each mixing cell has a cup with substantially cylindrical walls, the axis of the cup in being inclined at an acute angle to the vertical and about which axis the cup is rotated.

11. A sample preparation system as claimed in claim 10 wherein the said transport system is a chain conveyor on which mixing cells are mounted, aligned in transverse rows, each cup being mounted in a rotatable holder and characterised in that each holder in a transverse row is driven for rotation by an endless flexible belt.

12. A sample preparation system as claimed in claim 11 wherein the belt is driven by a rotating shaft which extends for substantially the full length of the horizontal travel of the conveyor, the belt sliding longitudinally with respect to the shaft. :

13. A sample preparation system as claimed in claim 12 wherein at the end of the mixing cycle a reduction in the diameter of the shaft reduces the tension in the belt, stopping the rotation of the mixing cells and allowing the contents to settle.

14. A sample preparation system as claimed in any one of claims 1 to 13 wherein the filter station includes: a drive roller to advance a continuous length of filter paper between an upper and lower filter block and a switch to detect to presence of paper to stop the drive roller; releasable clamping means to clamp and seal the filter paper in a flow passage between the said ’ upper and lower blocks; 40 a blade for separating the clamped section of filter paper from the continuous length;

means for passing the contents of a mixing cell to the upper filter block; means for collecting the filtrate from the lower filter block; and means for ejecting the used section of filter paper from between the filter blocks. N 5 15. A sample preparation system as claimed in claim 14 wherein the filtrate is drawn through the filter blocks by a vacuum and upon completion of a filtration cycle the filter blocks are washed with water.

16. A sample preparation system as claimed in claim 14 wherein the blade is operated by a reciprocating ram. ’

17. A sample preparation system as claimed in any one of claims 13 to 16 wherein the said means for ejecting the used section of filter paper from between the filter blocks includes: a traction roller mounted below the filter paper; a first air jet directed against the paper to separate it from one of the lower filter block; and a second air jet directed against the paper to separate it from the upper filter block, the said second jet also acting to increase the normal load on the traction roller to assist in driving the paper from between the filter blocks.

18. A sample preparation system substantially as described hereinbefore with reference to the accompanying drawings.

19. A method of preparing a sample of granular material, including the steps: providing a sample preparation system as claimed in any one of claims 1 to 18; providing a rack containing a plurality of open top containers; gripping a first container and removing it from the rack, inverting same and dispensing a measured volume of the granular material into a mixing cell; : metering a liquid reagent into the mixing cell; transporting the mixing cell to the filter station; and drawing a filtrate from the filter station. : )

20. A gripper-nozzle for an automated sample preparation system including: a flexible sleeve surrounding a frustroconical nozzle having a central flow passageway which terminates in a nozzle opening, the sleeve being inflatable by pressurised fluid to cause it to expand and contract between gripping and releasing positions respectively, and a connection for passing pressurised fluid to the interior of the sleeve, characterised in that the ) said nozzle includes an abutment member fixed about the external periphery of the nozzle and adapted to abut against a rim of the container. ’ 21. A gripper-nozzle as claimed in claim 20 wherein the said sleeve is adapted to be inserted into an 40 opening of a container and is made from elastomeric material

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22. A gripper-nozzle as claimed in claim 20 or claim 21 adapted for engagement with the mouth of the container having a necked portion wherein the inflated section of the sleeve engages below the necked portion. : 5

23. A gripper-nozzle as claimed in any one of claims 20 to 22 wherein the gripper-nozzle further \ mcludes a robot arm upon which the gripper-nozzle is mounted.

24. A gripper-nozzle substantially as described herein with reference to the accompanying drawings.

25. A method of gripping a container, including the steps: providing a gripper-nozzle as claimed in any one of claims 20 to 24; inserting an end of the nozzle into the mouth of the container until the abutment member abuts against the rim of the container mouth; and inflating the said sleeve by means of pressurised fluid to cause it to expand to a gripping position.

26. A dispenser for dispensing a measured volume of granular material, including a container having an opening to discharge the granular material into a cavity in a sliding block, which fills with material in a first position, and which dispenses material in a second position.

27. A dispenser as claimed in claim 26 wherein the dispenser includes: a horizontal base plate with a middle portion formed with an opening to receive granular material from the container; a sliding block mounted on a bottom side of said base plate, said sliding block having a granular material retaining cavity with substantially vertical walls and an outlet aperture that is aligned with said opening in said base plate in said first position; a plug valve fixed to the said sliding block for opening and closing the said outlet aperture; and power actuated means to slide the sliding block to the said second position whereby, granular material in said sliding block is discharged from said outlet aperture into mixing cell provided below said base plate when said sliding block is moved to said second position and the said plug valve is opened.

28. A dispenser as claimed in claim 26 or claim 27 wherein the said first and second positions are at the opposite ends of a linear reciprocating motion of the sliding block.

29. A dispenser as claimed in any one of claims 26 to 28 wherein the granular material is soil, having a predetermined moisture content and particle size distribution.

30. A dispenser substantially as described hereinbefore with reference to the accompanying drawings.

31. A method of dispensing a measured volume of granular material, including the steps: providing a dispenser as claimed in any one of claims 26 to 30; ¢ 5 placing the sliding block in the said first position and filling the said cavity; and sliding the said block to the said second position whereupon the material drops from the cavity.

32. A mixing apparatus for an automated sample preparation system including a mixing cell having a cup with substantially cylindrical walls, the axis of the cup in being inclined at an acute angle to the vertical and about which axis the cup is rotated.

33. A mixing apparatus as claimed in claim 32 wherein a plurality of mixing cells are mounted on a chain conveyor, aligned in transverse rows, each cup being mounted in a rotatable holder and characterised in that each holder in a transverse row is driven for rotation by an endless flexible belt.

34. A mixing apparatus as claimed in claim 32 or claim 33 wherein the belt is driven by a rotating shaft which extends for substantially the full length of the horizontal travel of the conveyor, the belt sliding longitudinally with respect to the shaft.

35. A mixing apparatus as claimed in any one of claims 32 to 34 wherein at the end of the mixing cycle a reduction in the diameter of the shaft reduces the tension in the belt, stopping the rotation of the mixing cells and allowing the contents to settle.

36. A mixing apparatus substantially as described hereinbefore with reference to the accompanying drawings.

37. A method of mixing the contents of a mixing cup, including the steps: providing a mixing apparatus as claimed in any one of claims 32 to 36; and rotating the said cup about the said inclined axis to mix the contents thereof.

38. An automated filter station including: a drive roller to advance a continuous length of filter paper between an upper and lower filter block and a switch to detect to presence of paper to stop the drive roller; releasable clamping means to clamp and seal the filter paper in a flow passage between the said upper and lower blocks; a blade for separating the clamped section of filter paper from the continuous length; ) means for passing the contents of a mixing cell to the upper filter block; means for collecting the filtrate from the lower filter block; and ’ means for ejecting the used section of filter paper from between the filter blocks. 40

:

39. An automated filter station as claimed in claim 38 wherein the filtrate is drawn through the filter blocks by a vacuum and upon completion of a filtration cycle the filter blocks are washed with water.

40. An automated filter station as claimed in claim 38 or claim 39 wherein the blade is operated by a “ 5 reciprocating ram. .

41. An automated filter station as claimed in any one of claims 38 to 40 wherein the said means for ejecting the used section of filter paper from between the filter blocks includes: a traction roller mounted below the filter paper; a first air jet directed against the paper to separate it from one of the lower filter block; a second air jet directed against the paper to separate it from the upper filter block, the said second jet also acting to increase the normal load on the traction roller to assist in driving the paper from between the filter blocks.

42. An automated filter station substantially as described hereinbefore with reference to the accompanying drawings.

43. A method of filtering a mixture, including the steps: providing a filter station as claimed in any one of claims 38 to 42; advancing paper from the continuous length of filter paper between the upper and lower filter blocks; detecting the presence of paper in the correct position and stopping the drive roller; clamping and sealing the filter paper in the flow passage between the said upper and lower blocks; separating the clamped section of filter paper from the continuous length; passing the said mixture to the upper filter block; collecting the filtrate from the lower filter block; and ejecting the used section of filter paper from between the filter blocks.