05/143134

07/23/1974

05/13/1971

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436/57

422/66, 422/67, 422/102, 422/71, 206/509, 206/459.500, 422/101, 422/61

G01N31/00; G01N33/53; G01N35/02; G01N33/16

23/23B,230,253,259,292 206/47A

3497320	AUTOMATED CHEMICAL ANALYZER	February 1970	Blackburn et al.
3504376	AUTOMATED CHEMICAL ANALYZER	March 1970	Bednar et al.
3540856	SAMPLE CAPSULE AND FILTERING MECHANISM	November 1970	Rochte et al.
3540857	SAMPLE CAPSULE AND FILTERING MECHANISM	November 1970	Martin
3622279	AUTOMATIC CHEMICAL TESTING APPARATUS	November 1971	Moran
3645692	PROCESS FOR THE PREPARATION, PRESERVATION AND TRANSPORTATION OF BLOOD AND SERUM SAMPLES FOR USE IN CLINICAL ANALYSES	February 1972	Stork et al.

Wolk, Morris O.

Serwin R. E.

Rose & Edell

I claim

1. A method for the performance of chemical and biological assays, comprising the steps of:

2. A method according to claim 1, wherein at said prior time a plurality of reactants are dispensed into a single chamber of said container and are freeze dried so that the reaction cannot proceed during the subsequent storage period.

3. A method according to claim 1, wherein at said prior time a plurality of reactants are dispensed into several separate chambers within said container, which chambers do not initially communicate with one another but are caused to communicate with one another at the time when the reaction is to proceed.

4. A method according to claim 3, wherein the dispensed reactants are freeze dried.

5. A method according to claim 1, wherein at the time of the assay reaction, the step of initiating the reaction within the container involves the addition of at least a diluent.

6. A method according to claim 1, wherein at the time of the assay reaction, the step of initiating the reaction within the container involves the addition of at least a sample for assay.

7. A method according to claim 1, wherein at the time of the assay reaction, the step of initiating the reaction within the container involves the addition of at least a further reactant.

8. A method according to claim 1, wherein the separation of the component to be quantified from other components of the reaction takes place within the container.

9. A method according to claim 1, wherein the separation of the component to be quantified from other components of the reaction involves filtration occurring through an opening in the base of the container.

10. A method according to claim 1, wherein a reactant is employed carrying a radioactive tracer and the quantifying step involves a radioactivity count.

11. A disposable combined storage and reaction cell, for use in the performance of chemical and biological reactions, adapted to receive reactants dispensed therein and to maintain the reactants in such stored condition that they remain stable and will not mutually react until such time as it is required to initiate the reaction, said cell comprising a number of chambers and being built up from separate interfitting sub-units that fit together end to end in series, each sub-unit containing a chamber.

12. A reaction cell according to claim 11, wherein the chambers are initially out of communication with one another and are adapted to be brought into communication with one another by manual operation of an externally accessible member.

13. A reaction cell according to claim 11, wherein one of the chambers constitutes a filtration chamber equipped with a removable filter disc.

14. A reaction cell according to claim 11, wherein one of the chambers constitutes an adsorption chamber containing a removable element on to which a reaction component is adsorbed.

15. A reaction cell according to claim 11, wherein the chambers are arranged to be brought into communication with one another by relative angular movement of the sub-units about a common axis.

16. In combination with a reaction cell according to claim 13, a filter carrier card adapted to receive a filter disc from the cell upon which a reaction component to be quantified has been precipitated and bearing also means for location of the disc and data relating to the particular reaction.

17. The combination according to claim 16, wherein said carrier card is made of sheet material and adapted to be secured end to end with other like cards to form a continuous band.

18. In combination with a plurality of reaction cells according to claim 11, a filtration unit comprising means for transporting a travelling band in stepwise fashion to bring each of a succession of filter web locations borne by the band to rest temporarily upon a vacuum filtration bed and means to hold a succession of said reaction cells immediately over the filter web upon said filtration bed at different respective ones of said filter web locations and to transport said reaction cells to and from said different filter web locations and said filtration bed.

19. The combination according to claim 18, further comprising a wash head for connection to the uppermost end of a reaction cell to supply wash solution thereto when said reaction cell is held as aforesaid over the filter web.

20. The combination according to claim 18, further comprising a data encoding unit encoding upon the travelling band data associated with the reaction performed in each reaction cell held as aforesaid.

21. In combination with a plurality of reaction cells according to claim 19, an isotope detector unit, comprising a travelling carrier band driven in stepwise fashion past at least one radioactive detector head connected to isotope counting equipment, the carrier band having at spaced intervals successive location sites each to bear a radioactive reaction component separated and withdrawn from a respective individual one of said reaction cells.

22. The combination according to claim 21, further comprising a data reader to read out encoded data related to the respective radioactive reaction components on the carrier band at said location sites.

23. The combination according to claim 21, further comprising a location control sensor to sense location markings on the carrier band and on a separate information band, to ensure correct swell and registration at the detector head and data reader.

24. In combination with a plurality of reaction cells according to claim 11, a carrier band adapted to carry a longitudinal strip of filter material providing individual filter web sites at regular pitch, and through each of which filter web sites filtration can take place in situ on the carrier band when a respective opened one of said reaction cells is held over said site.

25. The combination according to claim 24, further comprising means for the encodement of data pertaining to the respective reaction cells adjacent corresponding filter web sites.

This invention relates to the performance of chemical and/or biological reactions in laboratories, clinics and consulting rooms. It finds a special use in the case of reactions performed for the detection and quantitative measurement of natural and synthetic proteins, polypeptides and a variety of other molecular complexes including steroids and drugs.

The invention applies particularly to the techniques of saturation analysis including radioimmunoassay but is not restricted to these techniques. Saturation analysis relies upon progressive saturation by the test compound of a specific reagent. In radioimmunoassay, the specific reagent is an antibody, and the analytical system includes a known amount of the substance to be measured which is identifiable by a radioactive isotope. The substance to be measured is hereinafter referred to as the ligand. Quantitative measurement requires separation of the free ligand from ligand bound to specific reagent. Either free ligand or bound ligand, or both, may be measured.

These processes have a potentially wide application but have hitherto been limited in use because: (1) The specific reagents required are too difficult to prepare in non-specialised laboratories; and (2) Present methodology does not match in availability the temporal and spatial pattern of demand. The present invention offers a solution to these drawbacks by providing a novel method in which certain special components are employed. Furthermore, each such component is novel per se and can be used independently.

According to the present invention, the reactants used in the various techniques of saturation analysis and in which a radioactive marker is employed, are dispensed in a prior operation in amounts required for individual reactions and stored within the same container in a stable form. At the time of the assay operation, the reaction is initiated within the same container by the addition of a diluent, a sample for assay, some further reagent, or a combination of these. The reaction proceeds, additional agents may be added, and on completion of the reaction, or at some other definable stage in the reaction, the component to be measured, or a representative proportion of it, is separated from the other components of the reaction, removed from the container and, together with relevant identification data, is presented in a form for quantification and result read-out.

To facilitate the performance of this process a number of novel devices are provided.

The principal device is a reaction cell designed to facilitate dispensing the reactants into a container of suitable size and form, stabilization of the reactants so dispensed, their storage and transportation under various conditions of temperature and humidity, the addition of sample diluent or other agents and initiation of the reaction, and finally the separation of the component to be measured from the other components of the reaction.

Stabilisation of the reactants may be achieved by one of two alternative techniques. The first employs rapid freezing of the reactants followed by freeze drying within the same single chambered container, so that although the reactants are mixed at the time of dispensing the reaction does not proceed, at first because of the temperature and later because of the removal of water. The second technique is to dispense each reactant into separate chambers of a reaction cell, wherein each reactant is subsequently freeze dried. The reaction cell is so constructed that the reactants are kept separate from each other until the reaction is initiated; at this time the chambers are made to intercommunicate and allow the reaction to proceed, and the sample, diluent or other agents may be added. In any particular embodiment these two techniques may be combined.

In the preferred form of reaction cell filtration is employed using an external filter. The filter is then formed as a band of filter material or a carrier band incorporating filter locations at suitable intervals. To facilitate filtration, the base of this form of reaction cell is readily perforated, or otherwise opened, allowing the contents of the cell to be transferred directly to the filter material.

Alternatively, the reaction cell is arranged internally for filtration or collection by other means of the component of interest, and for fractionation or separation of the component of interest from the other reaction cell contents to facilitate its removal for examination. The cell may be suitable for centrifuging to promote collection or separation of the component of interest.

The component to be measured may be adsorbed on to a removable disc of plastic or glass within the reaction cell or it may be deposited on a filter membrane. The filter can be so located within the reaction cell that the whole process of separation can be completed within the reaction cell using a centrifuge or vacuum to urge the filtrate through the filter. At the end of such a process, the adsorption disc or filter can be removed from the reaction cell and submitted for counting of the radioactivity. This may be done in one of three ways. The disc may be returned to a central laboratory for counting and computation; the disc may be counted in a conventional isotope counting apparatus; the disc may be mounted on a card or flexible band as in the novel technique described hereinafter.

At the start of the reaction, data referable to the assay sample and to the reagents in the respective reactant cells is entered in a teleprinter device to produce a typescript of the sequence of samples entered and a similarly sequenced punch tape of the same data. These are used to ensure correct sample sequence and to facilitate computation of the results. This punch tape output from the teleprinter which is used in a subsequent stage of the process for computation is hereinafter described as the information band.

Where filtration takes place externally of the reaction cell, a special filtration unit may be employed to facilitate rapid and uniform operation. This filtration unit provides for filter membranes to be precisely registered at the filtration location and similarly provides for corresponding location of each reaction cell. A conveyor belt, or similar device, may be incorporated in the filtration unit to receive reaction cells and convey them to and from the filter location. After this location has been established the reaction chamber of the reaction cell may be opened to the filter bed by an appropriate mechanism on the filtration unit. The filtration unit enables vacuum to be applied and wash solution to be passed through the reaction cell and filter in a constant and reproducible fashion. The filtration unit may further provide for quantitative collection and isotopic counting of the filtrate or for disposal of the filtrate, and for filter carrier bands to be drawn from speeds and fed either directly to an isotope detector unit or to a take-up spool. The latter alternative facilitates different rates of operation at the filtration and isotope counting stages.

In the case where filtration or adsorption is employed within the cell the filter membranes or adsoption discs are removed from the cell and mounted on suitable cards or carried bands. The carrier cards or carrier bands may have the further function of carrying encoded sample and reactant data as an alternative to the teleprinter system referred to above. In this way the radioactive and measurable component of the reaction is directly associated with information related to the reaction thus ensuring that the results are linked to the appropriate sample. These carrier cards and carrier bands may also be punched to provide sprocket holes or other marker devices to ensure their precise registration at different locations in the process.

The filter carrier band or carrier cards may be fed directly to the isotope detector unit on a travelling band, or may be transferred to it on a spool, or as a stack of cards. The detector unit has a head or heads to detect the radioactivity of the filter or adsorption disc and to transmit the output to isotope detecting equipment. It has the further function of reading encoded data on the information band or on the filter carrier cards or carrier bands and feeding this to the computer or calaculator or other output device. By these arrangements, the isotopic activity on a "sample" disc may be related to that on "reference" discs incorporated in the assay, or to data supplied about such reference materials, further correction factors may be applied, the results of the assay computed in terms of standard units, and this printed out by the output device together with sample identification data.

Individual cards receiving filter or adsorption discs and encoded data can carry trays or adhesive areas to secure the filter membrane thereto, and/or to secure one mount to another to form a carrier band.

Arrangements for carrying the invention into effect will now be more particularly described, by way of example, and with reference to the accompanying drawings, in which:

FIG. 1 is an elevation, in section, of one form of multi-chamber reaction cell,

FIG. 1A shows an occlusive rod for use with such a cell,

FIG. 1B shows a perforating probe for use with such a cell,

FIG. 1C shows an adsorption disc for such a cell,

FIG. 2 is a plan view of the cell,

FIG. 3 is an elevation, in section, of an adsorption sub-unit that can be used with the cell of FIG. 1,

FIGS. 4 and 5 are, respectively, a sectional elevation and a plan illustrating an alternative form of reaction cell,

FIG. 6 is a diagram of a unit for external filtration,

FIGS. 7 and 8 are, respectively, diagrammatic plan and elevational views of one form of filter carrier band or card,

FIG. 9 shows one form of isotope detecting unit and the associated feed apparatus, and

FIG. 10 is a complete flow sheet of the process of analysis.

The reaction cell is a container so constructed as to allow the reagents to be maintained in a stable, non-reactive state prior to the addition of the sample; and subsequently to facilitate their interaction and finally to facilitate identification and quantification of a fraction of the reactants.

The reaction cell is preferably, but not necessarily, cylindrical in form and can be centrifuged. It consists of one block containing a plurality of chambers or channels, or alternatively, for ease of manufacture and preparation, consists of several co-fitting sub-units which together form chambers or channels.

The reaction cell may be made in any suitable material but `non-wettable` plastics such as polystyrene or polypropylene are preferred; a combination of rigid or semi-rigid plastics and flexible plastic materials such as polythene or gelatin may also be used.

Such reaction cells can be constructed in many different ways. Moreover each reaction cell may comprise a number of identical sub-units, or a number of differing and more or less specialised sub-units, or be formed within a single structural unit. The particular form of reaction cell shown in FIGS. 1 and 2 includes four similar sub-units.

Each sub-unit 11 is a modified cylinder with an upper axial flange 12 to facilitate interlocking with a reduced diameter lower end portion 13 formed at the base of another similar sub-unit above. The abutting faces 14 of the flanges 12 and reduced diameter portions 13 are slightly tapered so as to provide a tight seal; alternatively, they may be made to interlock by suitable threads or lugs etc. Internally at the base of each flange 12 a narrow shelf 15 is formed and below this the internal walls 16 of the sub-unit are parallel to, or funnel steeply in towards the central aixs. One or more additional shelves or recesses may be formed in these walls 16, if desired, to provide locations for an occlusive rod 20, such as that shown in FIG. 1A, and/or a perforating probe 21, such as that shown in FIG. 1B. Occlusive rods and perforating probes may contain internal channels 27 to facilitate the access of wash fluid to the reaction cell during the filtration stage.

The funnel walls 16 terminate in an intact base 17, which is of such strength that it does not disrupt under the moderate gravitational loads encountered in use (unless this is so desired) but can be readily perforated by a suitable probe. Perforation may be facilitated by grooving of the base plate. The shelf 15 formed below the upper flange provides a limit stop to the depth of penetration when the lower end of one sub-unit 11 is forced into the upper end of another. It can also serve as a support ring for a filter support and filter membrane. The filter support 18 is a rigid, or semi-rigid, disc of, for example, porous polythene, with a pore or mesh size greater than that of the filter membrane. The filter membrane 19 is selected according to pore size and other characteristics such that it will retain bound ligand and pass free ligand, and may consist of cellulose acetate or glass fibre film or other such suitable material.

When used with filtration on an external filter bed the internal filter 19 and filter support 18 are omitted. When internal filtration is to be vacuum assisted, diaphragm 17 is omitted. When internal filtration is performed by centrifugation a fine capillary channel may be provided in the wall of the lowermost sub-unit to allow displacement of air by the incoming filtrate.

Alternatively to the filtration system, the reaction cell may include in, say, the lowest sub-unit 11, a removable reactant-bearing membrane, made of polystyrene or other suitable material, having adsorbed or otherwise attached to its surface, one or more of the reactants. In use, this membrane becomes immersed in the reactant solution. Such a membrane 22 is shown in FIG. 1C; it may be located so as to be totally exposed on one or both surfaces. To facilitate perforation of the sub-unit base 17 and washing of the membrane the central portion of the membrane may be apertured as at 23.

FIG. 3 shows a different form of sub-unit 24 in which the internal chamber 25 is generally cylindrical and has projections 26 upstanding from its floor on which an adsorption disc 22 may rest.

FIGS. 4 and 5 show an alternative form of reaction cell, in which separate chambers 28 are brought into or out of communication by relative angular movements of generally cylindrical sub-units 29 of the cell in which the chambers 28 are formed as bores extending through in the axial direction but offset from the axis of rotation. The relative angular movement may be facilitated by the provision of finger tags 30 on the sub-units.

In the preparation laboratory the reaction cell and other components including the filter disc 18 may be dip-treated in appropriate solutions to inhibit non-specific adsorption of reagents.

The reagents may be dispensed into the chambers or sub-units 11, 28 in liquid form or as measured amounts of gel, powder or crystal, or in encapsulated form. The preferred method is to dispense as liquid and then to freeze dry, enclosing dry gas or air in the sub-unit. Each freeze drying operation may be performed separately, with each succeeding sub-unit base being used to seal the contents of the next lower sub-unit. Alternatively, two or more sub-units of the same reaction cell may be submitted to freeze drying in one stage.

In addition, buffer solutions, precipitating solutions and other agents may be dispensed into further sub-units. Also, reaction cells are prepared containing appropriate quantities of reference preparation of the ligand.

The preparation laboratory may also undertake assays with each batch of reagents and reference standards and from the information derived provide the analysing laboratories with data relevant to the analysis and which may permit a reduction in the number of reference standards required or in eliminating the need for such standards in the analysing laboratory.

In the analysing laboratory the operator adds a defined amount of the sample, or diluted sample, to the reaction cell by micro-syringe or other suitable device. Data relevant to the sample and reactants are entered on the teleprinter at this stage. At about the same time where a multi-compartment reaction cell is used, the operator introduces and depresses the perforating probe 21 to the first position to open communication with the next sub-unit below and rotates the probe to ensure mixing. After light centrifuging the reaction cell is incubated for a period defined by the particular assay being performed.

After incubation, the reaction cells are transferred to the filtration unit in sequence, previously recorded either manually or by teleprinter at the time of introducing the assay samples.

FIG. 6 shows a unit such as can be employed when filtration is to be carried out externally of the reaction cell. This unit has a conveyor band 31 drawn from a supply spool 32 and passing over vacuum filtration beds 33 and 34 to a take-up spool 35. Incorporated at intervals along the band 31 are filter locations as at 36. The band is fed stepwise and the filters are brought to register at a succession of stations.

At the first of these, 37, the filter membrane may be soaked in a solution to prevent non-specific adsorption of reactants to the membrane. The solution may contain albumin or similar. It is supplied by a nozzle 38 from a reservoir 39 by a pump 40 and tubing 41. Surplus pre-soak solution may be drawn to waste 42 by a vacuum pump 43, via a sink 44 connected by appropriate tubes 44a to ballast tank 45 and control valve 46, or by some other convenient means. Additional air lines and anti-foaming agents may be introduced into such a vacuum system to prevent frothing.

The filter membrane is moved stepwise to location 47 over the porous filter support 48 which is connected to a vacuum line 49, control valve 50 and thus via ballast tank 45 and vacuum pump 43 to waste 42. Alternatively, a filtrate may be collected and transferred to a liquid isotope counting unit to supplement counting of radioactive precipitate.

Station 47 is surmounted by means for receiving and holding a reaction cell 51 and a mechanism 52 for depressing the perforating probe 53 through the lowermost diaphragm 54 of the reaction cell 51 and thus allow filtration to take place.

At this same station 47, or at a multiplicity of similar stations, or at a subsequent station as at 34, a wash head 55 is attached to the uppermost end of the reaction cell 51; this head supplies to the reaction cell wash solution from a reservoir 58 via pump 59 and tubing 60. Such a station 34 is equipped similarly to station 47 with a vacuum source to draw liquid through the filter and to waste 42.

Reaction cells are transferred to the filtration unit singly or in batches. To facilitate batch processing the reaction cells 61, 62, 63 may be placed in sequence in a magazine fitted with a conveyor mechanism 64 which transfers them stepwise, and at the appropriate time and for the appropriate dwell times, to the filter location 33 and then to wash location 34 and thereafter conveys them away from the filtration bed, as at 65, for disposal.

Alternatively, the pre-soak, filtration and wash functions may be carried out successively at the same station or at a multiplicity of similar stations.

After washing, the filter membrane may be passed over a drying location 66 incorporating a heating element 67 and fan 68.

Beyond this may be located a mechanism to ensure precise registration of the filter membranes at the various locations of the unit. This may consist for instance of a sprocket drive 69 engaging in appropriate holes on the filter carrier band 31. Alternatively or additionally, there may be included a magnetic or photoptic device or similar 70 which detects a corresponding marker on the carrier band 31 and transmits a signal to the drive mechanism for the carrier band 31 and the drive mechanism for the reaction cell conveyor mechanism 64.

Where a teleprinter device is not included in the system, a data punch 71 may be included for encodement of data relating to sample and reagents and may be positioned at the location indicated.

The carrier band 31 in the filtration unit can be reeled on the take-up spool 35 and the complete spool transferred, after rewinding to obtain the correct sequence, becomes the supply spool of the isotope detector unit, or alternatively, the band 31 can be led directly to the detector unit, if the speeds of the filtration and counting operations are compatible.

Alternatively to external filtration, and where internal filtration is employed, on completion of incubation the perforating probe is depressed to the second position to open communication with the filter sub-unit and then withdrawn to the upper position. After centrifugation, a buffer solution sub-unit may be fitted to the reaction cell and may now have its base perforated by the upper end of the perforating probe. The reaction cell is again centrifuged and the filter membrane disc 18 then transferred to a filter carrier band or card to be hereinafter described.

Where the analysing laboratory does not wish to perform computation the preparation laboratory may provide an isotope counting service. The reaction cell disc 18 is returned to the preparation laboratory, counting and computation performed and the result returned to the analysing laboratory.

Referring now to FIGS. 7 and 8, these show a filter carrier band or card. This device provides a means for the transportation (and positioning) of the filter membrane or adsorption disc from the reaction cell, at one of a succession of appropriately pitched stations on a carrier band 31, to the radioactivity detector.

The device is a strip of card 31 or other suitable material such as paper or plastic so formed as to receive the disc 72 in a recess 73 in which it lies slightly below the surface of the mount; the recess 73 may have a floor opening so that the disc 72 can be exposed on both surfaces except at its periphery where it may be secured by adhesive, or otherwise.

The strip of carrier band may be of such length as to accommodate a single filter and associated features to be described below, or to accommodate several hundred such filters, or any intermediate number.

Short lengths can be joined end to end by any single means, such as by projecting end margins 74 of the individual card plies, or can be accommodated on an appropriately perforated continuous secondary mount 75, to form lengths which can be coiled on suitable spools. Each band or card may, if desired, additionally incorporate marginal notches 76 and/or sprocket holes 77 and a mechanical or photo-optic marker 78 to facilitate precise location of the disc 72 at the detection location.

Where the carrier band is employed with filtration external to the reaction cell the carrier band is normally prepared with filters 72 fitted in the appropriate recesses 73. Where filtration is carried out within the reaction cell, or where an adsorption disc is used, the carrier band recesses are void until such filter or adsorption discs are inserted.

Further where external filtration is employed manufacture of this device may be simplified by use of a tape of filter material such as glass fibre which is disposed along the length of the carrier band and held to the carrier band by adhesive, or by punching or crimping of the carrier band.

Between or beside filter locations the carrier band may provide a site 79 for the encodement of data related to sample or reagents such data being encoded thereon by the device 71 already described.

Referring now to FIG. 9, the function of the apparatus shown therein is to detect the radioactivity on the carrier band 31 and read the encoded data on the information band 80, or encoded on the carrier band 31, and to transmit appropriate signals to receiving devices. The filter carrier band 31 obtained from the supply spool 81 is guided by rollers 82, via the isotope detector location 83 to a take-up spool 84 or is routed to waste.

The information band 80, derived from teleprinter in the system, is received on a spool 85 which may be co-axial with the filter carrier spool 81 and is similarly guided by rollers 86 via the data reading device 87 to take-up spool 83 which may be co-axial with the take-up spool 84 of the carrier band.

Transport of the carrier 31 and the information band 80 may be effected by pinch rollers at locations 82, 86 and/or by sprockets as at 89, 90, engaging in suitable holes in the carrier band and information band. By use of associated timing equipment transport of the filter carrier band and information band is controlled in a stepwise manner with predetermined increments of advance and dwell-times so that signals derived from the radioactive sites and encodement sites on the respective bands may be received in a co-ordinated manner and likewise transmitted to suitable receivers.

Alternatively, or additionally, a photo-sensitive cell 91 or similar device may be used to control the carrier band feed, thus obviating the need for or supplementing the operation of sprocket rollers and associated equipment. Such a device may sense the position of each radioactive precipitate, or a marker associated therewith, and transmit a signal to arrest the movement of the carrier band at the appropriate position and for the requisite period for counting.

The roller pairs 82, 86 incorporate a friction device which maintains a constant restraining effect on the carrier band 31, and the information band 80, while these are travelling through the detector heads 92, and data reading heads 87, thus keeping the bands taut and central between the heads.

The apparatus includes photomultiplier scintillation detectors or Geiger-Muller heads or similar detectors 92 (herein afterwards described as detector heads). These heads may be installed in-linc or in parallel, and in single or multiple pairs. The output signal from the detector heads 92 is transmitted to radioisotope counting units or via a pulse height analyser and interface to a computer.

The data reader 87 is matched to the form of encoded data on the information band 80 so that where a teleprinter with paper punch is used at the start of the assay for encoding the sequence of samples and associated data the data reader is a punch tape reader. Alternatively, where data has been encoded on the filter carrier band 31, the appropriate form of data reader 93 may be located on the path of the filter carrier band either upstream or downstream of the detector head 92. The output signal from the data reader is transmitted to the on-line computer. The computer is programmed to associate the data from the data reader with the corresponding isotope count signals, to perform the appropriate calculations and send output signals to the teleprinter or other output device.

FIG. 10 shows, in the form of a flow sheet, the complete progression of an analysis sample through the process of analysis.

At 94 the sample is introduced into the reaction cell, and data relevant thereto is entered in the teleprinter 95 to produce a typescript 96 of the sequence of samples entered and a corresponding punched tape information band 97.

After the reaction has been subsequently initiated within the reaction cell, the cell is incubated at 98 and then transferred to the conveyor of the filtration unit 99 previously described with reference to FIG. 6. After filtration, the carrier band spool 35 is rewound at 100 and transferred to the isotope detector unit 101 previously described with reference to FIG. 9. The carrier band, and the information band 97 from the teleprinter, are fed together through the detector unit 101 and the detector heads 92 deliver signals to the isotope counter 103 which in turn feeds the computer 104 while the data reader 87, linked to the teleprinter 95 and the computer 104, simultaneously transmits the data on the information band to the computer. The final read-out takes place through the teleprinter 95.

Many other modifications of the equipment described are possible without departing from the scope of the invention. Thus, a multi-chamber reaction cell, instead of being built up from separate sub-units, can be moulded all in one piece, with rupturable diaphragms or occlusion rods preventing communication between one chamber and another until the reaction is to take place. Also, it has already been explained how the technique of rapid freezing followed by freeze drying enables a single chamber reaction cell to be employed. Instead of external measurement, measurements may in certain cases be made on material while still within the cell; one way of achieving this is to incorporate in the cell a chromatographic wick or the like.