GB1595079A - Immersion dialyser - Google Patents

Description

(54) IMMERSION DIALYSER (71) We, BOEHRINGER MANN HEIM GMBH, of 112-132, Sandhofer Strasse, 6800 Mannheim-Waldhof, Federal RepubLic of Germany, a Body Corporate organised under the laws of the Federal Repub- lic of Geranany, do hereby declare the in Invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particaarly described in and by the following statement: - The present invention is concerned with an immersion dialyser which can be immersed directly into the medium to be dialysed and which can preferably be sterilised.

For the dieterminlation of substrates and of other dissolved substances in sterile media which are present in a reactor, a storage vessel, a fermenter or the like, it is generally necessary to take samples which, on the one hand, reduces the volume of the medium to be determined and, on the other hand, gives rise to the danger that the medium becornes contaminated or infected, infection frequently resulting in expensive losses.

Various systems have already been desbribed and used for sterile sampling (G. L.

Solomons, "Materials and Methods in Fermentation", pub. Academic Press, London, New York, 1969).

So long as a Large volume of the medium is available, it is acceptable to withdraw the samples necessary for analyses, although a latent danger of infection always exists. However, it is more difficult when samples must be withdrawn from a comparatively smal batch several times per day for a comparatively long time since, in such oases, frequent analyses are forbidden because of the automatic reduction of the volume of the medium.

Thus, it is an object of the present m- Invention to provide a dialyser which is es pedally useful for analytical purposes, which does not reduce the volume of the medium and which reduces the danger of infection to a minimum.

This object is achieved by the immersion dialyser provided according to the present invention, which can be incorporated into or introduced into a vessel in the manner of a probe and which can be sterilised before or after incorporation into a vessel.

Thus, according bo the present invention, there is provided an immersion dialyser aam- prising a dialysis head with a tip potion enclosed within a removable membrane stretched over it and mounted thereon, the head having a body with at least one inlet canal and a return canal; the head body being removably connected to a tubular member containing at least one inlet pipe removably connected with said inlet canal and a return pipe removably connected with said reum canal; do sure means being provided for the tubular member.

In one embodiment, the head body has a flat end with a raised edge region to provide said tip over which the membrane is mounted.

In another embodiment, the head body has a flat end to which a domed sieve is fitted to provide said tip portion. In other embodiments the head body itself has a conically, rounded or rotation paraboloid4ike shaped end or tip portion. For the better distribution of a buffer solution in contact with the membrane, the tip portion is preferably provided with longitudinal and transverse grooves and, more preferably, with a spiral groove with a rounded base running up to the tip which connects the inlet canal with the return canal.

The dialysis head is made from an inert and sterilisable material preferably from a synthetic resin and especially from polytetrafluoroethylene. On its lower end, the dialysis head is provided with annular grooves which permit a tight and firmly-seated connection of the dialysis head with the tubular member.

Conveniently, the tip portion of the dialysis head has a membrane holder in the form of one or more annular grooves running round the circumference of the dialysis head into which can be placed rubber Zings which secure the dialysis membrane drawn over the tip of the dialysis head.

In a preferred embodiment, the inlet and return canals which extend through the dialyser bead tonninate at different positions of the tip so that a buffer solution passing by the dialysis membrane contacts a mem brane surface area which is as large as possible. The ends od the inlet and return canals can be provided with threads for the screw connection of the inlet pipe and of the return pipe, these pipes being passed through the tubular member and closure means provided with appropriate passages for the pipes. On the ends of these inlet and return pipes there are fixed rubber or synthetic resin tubes, pre ferably Tygon (Registered Trade Mark) tubes, by means of which the immersion dialyser is connected with an appropriate analysis device, for example an automatically operating analysed.

According to a preferred embodiment of the present invention, the dialysis head is provided with an external thread on to which can be screwed a protective grid made of an inert sterilisable material and preferably of stainless steel, so that the sensitive dialysis membrane is protected against damage. For storage purposes, over this protective grid there can be pushed a rubber aap provided with a bead in order to ensure that the membrane does not dry out.

The inlet and return canals and the inlet and return pipes connected therewith pre ferably have an inner diameter of 0.5 to 3 mm.

and more preferably of about 1 mm. The spiral groove provided on the tip of the dialysis head preferably has a depth of 1 mm.

and a breadth of 1.5 mm. and :Is SO made that it does not have any sharp edges which could damage or destroy the sensitive dialysis membrane.

The tubular member, the inlet pipes or the return pipe are made from an inert, seerilis- able material and preferably from stainless steel, whereas the closure means can be made from any appropriate material, for example a synthetic resin.

It is, however, important that only those matez1iad6 are employed for the production of the immersion dialyser which can be subjected to a sterilisation treatment, can preferably withstand temperatures of up to 150or.

and are stable to oxidation and corrosion.

The longitudinal or transverse grooves pro- vided on the tip of the dialysis head and the spiral groove can be milled in, injection moulded, turned or pressed in. The breadth and the number of the windings of the spiral grooves is responsible for the dialysis yield sil oe hereby the largest possible surface area of the dialysis membrane comes into close contaot with the buffer solution passing by it.

The tubes connected with the inlet and return pipes preferably have an inner diameter of 0.7 to 0.8 mm. and must withstand the sterilisation pressure, which can be up to 1.5 ats.

For a hatter understanding of the present invention, reference is made to the accompanying drawings, in which: Fig. 1 is a schematic sectional view of a first embodiment of the immersion dialyser according to the present invention; Fig. 2 is a schematic sectional view d a second embodiment of the immersion dialyser according to the present invention; Fig. 3 is a schematic sectional view of a third embodiment of the immersion dialyser according the the present invention; Fig. 4 is a schematic sectional view of the most preferred embodiment of the immersion dialyser according to the present invention; and Fig. 5 is a view of a dialysis head and of a protective grid suitable therefor.

Fig. 1 illustrates an embodiment of the immersion dialyser according to the present invention which is fixed, with the help of holding means 26, on to a fermenter or a bypass. The immersion dialyser coniprises a dialysis head 1 having a body which is provided with a raised edge region 10 to pro- vide a tip portion over which is stretched a membrane 8. The membrane 8 tis laid round over the edge region and a part of the dialysis head and is firmly held on to the dialysis head tip portion with the help of a rubber ring 17. Into the dialysis head 1 there are incorporated, spaced apart, an inlet canal 3 and a return canal 4, through which the buffer solution necessary for the dialysis flows in and out. Since the membrane 8 is in direct contact with the medium to be analysed, all dialysable materials are, without reduction of the volume of the medium, withdrawn via the immersion dialyser and can then be transferred to an analysis device. The buffer solution is fed through an inlet pipe 6 into an inlet canal 3 and withdrawn through a return canal 4 and a return pipe 7. The dialysis head is fixed with the help of rubber seals (not illustrated in Fig. 1) on to a holder tube 5, the end of which remote from the dialysis head is provided with closure means 9, for example a closure stopper, through which are passed the inlet and return plipes 6 and 7.

In the oase of this embodiment, under the membrane there is formed a small buffer chamber which, via the inlet and return canals and the inlet and return pipes, is con- nected with an analysis device, for example an Eppendorff photometer. After passage through a reaction coil, there can, for example, be quantitatively determined the glucose taken up by the dialysis procedure without it being necessary to take samples m a laborious manner.

Fig. 2 shows a schematic view of a second embodiment d the immersion dialyser accofd- ing to the present invention which comprises a flat ended dialysis helad body provided with a domed sieve 11 over which the membrane 8 is stretched. The membrane is, in turn, fixed with the help of a rubber O-ring 17 on to the membrane holder 2 and the dialysis head 1.

By means of this metal sieve, the membrane can be more tautly stretched than is possible in the oase of the embodiment illustrated in Fig. 1 so that a more constant dialysis yield can also be achieved.

Fig. 3 shows a third embodiment of the immersion dialyser according to the present invention. The dialysis head of this embodi- ment has a aonica ly shaped tip 12 which is provided with sverse and longitudinal grooves 13, these grooves bringing about a more uniform distribution of the buffer over the surface of the membrane. The buffier solution necessary for the dialysis is fed in via op positely-lying inlet pipes 6 into the inlet canals 3 and from there via the grooves to the Teflon (Registered Trade Mark) tip from whence the buffer solution is again withdrawn via the return canal 4 and the return pipe 7. In this case, too, the dialysis membrane 8 is tautly fixed on the dialysis head 1 with the help of the rubber O-rdng 17. In the case of this embodiment, an even more uniform dialysis yield can be achieved and the immersion dialyser is substantially more stable, which simplifies its sterbisation.

Finally, Fig. 4 shows the prefenred embodiment of the immersion dialyser acoord- ing to the present invention in a scheinatic exploded sectional view. The dialysis head 1, which is preferably made of polytetra fluoroethylene, has a rounded tip 12 provided with a spiral groove 14 with a rounded base 15 running towards the tip. This spiral groove connects the inlet canal 3 with the return canal 4 and advantageously has 3 or 4 windings. The spiral groove can be milled in, injection moulded, turned or pressed in but, nevertheless, preferably has round--ed edges in order that damage to the sensitive mem brane is avoided. The membrane 8 is placed over the tip 12 of the dialysis head and tightly secured to the dialysis head with the help of rubber Orugs placed in the annular grooves 16. The rear end of the dialysis head 1 is provided with annular grooves 19 into which rubber O-nings can be placed which make possible a tight connection of the dialysis head 1 with the holder tube 5.

The ends of the inlet canal 3 and of the return canal 4 are provided with threads 20 into which oan be screwed corresponding threads 27 of the inlet pipe 6 and of the return pipe 7, respectively. The inlet and return pipes 6 and 7 pass through the holder tube 5 and through the closure stopper 9 which is provided with tightly fitiing tube passages 24. These pipes are preferably made of stainless steel and advantageously have a diameter of 1 mm., whereas the pipe passages 24 have a diameter of 1.2 rain. The closure stopper 9 is provided with an annular groove 25 for the reception of a sealing rubber O-ring.

The spiral groove 14 incorporated into the tip 12 of the dialysis head passes the buffer, in an aimed manner, over the dialysis head.

Air is thereby forced out so that no air bubbles oan be formed, which results in a constant dialysis yield. The dialyser is stable towards a sterilisation and can be introduced or incorporated directly into a fermented.

Fig. 5 shows the dialysis head 1 provided with an - outer thread 21 and a protective grid 23 suitable therefor. The protective grid 23 can be firnily screwed, with the help of an internal thread 22, on to the dialysis head 1 and, in this manner, protects the sensitive dialysis membrane. Over the protective grid 23 there can be pushed an appropriately shaped rubber cap which should sit as tightly as possible in order to prevent a ruining off or evaporation of the disinfection solution in the presence of which the membrane is preferably stored.

The dialysis membrane used can be made af 'any suitable material, such as cellulose or a synthetic resin and especially "Cello- phase" (Registered Trade Mark). It is pre felrable to use a "Cellophane" dialysis tube with a surface breadth of 75 to 85 mm. and a diameter of 50 mm. (obtainable from the Kale, gubsizDiary of Hoechst A.G., Wies laden). The pore size of the membrane depends upon the material to be dialysed and is preferably 4 to 6 mn.

The immersion dialyser according to the present invention can be dipped into the medium to be analysed like a probe and is preferably directly incorporated into the fermenter.

When using the immersion dialyser, all dialysable materials present in the medium to be analysed are taken up via the dialyser head and the membrane into a buffer current of appropriate composton. The rate of flow of the buffer stream is regulated in such a manner that the substances to be determined are present on both sides of the membrane in dialysis equilibrium. The "saturated" buffer current is transported to the actual analysis system and, possibly after reaction with an indicator, subsequently analysed. In this way, practically all materials which oan be separated from the medium by dialysis can be passed to an analysis.

No volume losses occur, there is no danger of infection, difficult sample taking op era- tions are unnecessary and the preparation of samples, such as filtration and centrifuging, are also unnecessary. This represents a considerable advantage in comparison with oonventional systems for taking samples since there, in the case of withdrawal of the sample, the problem arises that the tubes and dialysis chamber very quickly become blocked Up so that these must be frequently disassembled and cleaned. In the case of the conventional manipulations and also the neces sary pumping round, there is a very high danger of infection which, in the case of the immersion dialyser according to the present invention, no longer exists since it can be sterilised.

By means of the immersion dialyser according to the present invention, in the case of mycel!ium-containing (for example Aspergillus niger) deposits, the filtration is unnecessary which previously caused very great difficulties and, without supervision, also could not be carried out over the course of a short period of time.

The immersion dialyser according to the present invention guarantees a continuous taking of samples without loss of volume and without the danger of infection and can be directly attached to an automatic analyser.

Since it is stable towards sterilisation, the immersion dialyser can be sterilised, for example by sterilising the immerrion dialyser inoorporated into a fermenter.

For using the immersion dialyser, the inlet and return pipes 6 and 7, preferably made of stainless steel, are first screwed on to the dialysis head 1. They are introduced through the holder tube 5, which is made of stainless steel and preferably has a diameter of 19 mm., whereupon the dialysis head is pressed into the holder tube 5. The Orings laid into the annular grooves 19 thereby ensure a good sealing and a firm seating.

The closure stopper is then put on, which is also fixed in the holder tube 5 with the help of an O-ring laid into the annular groove 25, care being taken that the inlet and return pipes do not interlace or cross over.

Then, with the help of tubes, preferably Tygon tubes, with an inner diameter of 0.7 to 0.8 rain., the immersion dialyser is con necked with an analysis device.

The dialysis membrane is cut to a size of 6 X 6 cm. and softened in a 0.1% disinfection solution, for example a sodium azide solution, softening taking place over the course of at least one hour. However, it can be carried out for an unlimited period of time.

For pulling over, the membrane is placed squarely in the middle of the dialysis head.

It is then pulled uniformly downwards, taking care to avoid creasing or folding the surface of the membrane. The membrane stretches sufficiently. The O-ring6 are now carefully rolled on from the direction of the tip of the dialyser head, over the membrane into the annular grooves 16, the membrane thereby being in a stretched condition. Excess membrane is then removed below the lower Ovine, whereafter the protective grid 23 is screwed on.

In the case of comparatively long non-use, a rubber cap filled with a 0.1% sodium azide disinfection solution is pushed over the pro tective grid in order to avoid a drying out of the membrane.

The membrane can be sterilised several times and, after a possible damaging, can be changed without difficulty.

When assembling the immersion dialyser, the threads 20 and 27 are preferably sealed with the help of sealing materials and es specially with a polytetrafluoroethylene band.

When the immersion dialyser is to be sterilised in an incorporated state, together with the fermenter, the membrane must be protected against bursting by the superimposition of pressure. This takes place by providing the inlet pipe 6 with a connection and con- necting the return pipe 7 with the fermenter chamber. In the case of sterilisation, the pressure on both sides of the membrane builds up equally strongly so that there is no danger of damaging the membrane. When sterilisation is finished and after the pressure has again been relieved, the superimposed pressure is removed, whereupon the immersion dialyser is, with the belp of tubes, again connected to the continuously operating analyser.

Before the sterilisation, these tubes must be filled with liquid at the lowest plossible pump rate in order to prevent the formation of a pillow of air.

The immersion dialyser according to the present invention can be sterilised not ody in a liquid but also with steam at a tem- perature of about 1200C.

WHAT WE CLAIM IS:- 1. An immersion dialyser, comprising a dialysis head with a tip portion enclosed within a removable membrane stretched over it and mounted thereon, the head having a body with at least one inlet canal and a return canal; the head body being removably connected to a tubular member containing at least one inlet pipe removably connected with said inlet canal and a return pipe removably connected with said return canal; dosure means being provided for the tubular member.

2. An immersion dialyser according to claim 1, wherein the dialysis body has a flat end with a raised edge region to provide said tip portion over which the membrane is mounted.

3. An immersion dialyser according to claim 1, wherein the dialysis body has a fiat end to which a domed sieve is fitted to provide said tip portion over which the membrane is mounted.

4. An immersion dialyser according to claim 3, wherein the sieve is made of a metal or of a synthetic resin.

5. An immersion dialyser according to claim 1, wherein the dialysis head body has a coni- aallyeshaped tip provided with transverse and longitudinal grooves, said tip being enclosed by the membrane mounted thereon.

6. An immersion dialyser according to claim 1, wherein the dialysis head body has a rounded tip which is provided with a rounded base spiral groove running to the tip, said

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (20)

**WARNING** start of CLMS field may overlap end of DESC **. sary pumping round, there is a very high danger of infection which, in the case of the immersion dialyser according to the present invention, no longer exists since it can be sterilised. By means of the immersion dialyser according to the present invention, in the case of mycel!ium-containing (for example Aspergillus niger) deposits, the filtration is unnecessary which previously caused very great difficulties and, without supervision, also could not be carried out over the course of a short period of time. The immersion dialyser according to the present invention guarantees a continuous taking of samples without loss of volume and without the danger of infection and can be directly attached to an automatic analyser. Since it is stable towards sterilisation, the immersion dialyser can be sterilised, for example by sterilising the immerrion dialyser inoorporated into a fermenter. For using the immersion dialyser, the inlet and return pipes 6 and 7, preferably made of stainless steel, are first screwed on to the dialysis head 1. They are introduced through the holder tube 5, which is made of stainless steel and preferably has a diameter of 19 mm., whereupon the dialysis head is pressed into the holder tube 5. The Orings laid into the annular grooves 19 thereby ensure a good sealing and a firm seating. The closure stopper is then put on, which is also fixed in the holder tube 5 with the help of an O-ring laid into the annular groove 25, care being taken that the inlet and return pipes do not interlace or cross over. Then, with the help of tubes, preferably Tygon tubes, with an inner diameter of 0.7 to 0.8 rain., the immersion dialyser is con necked with an analysis device. The dialysis membrane is cut to a size of 6 X 6 cm. and softened in a 0.1% disinfection solution, for example a sodium azide solution, softening taking place over the course of at least one hour. However, it can be carried out for an unlimited period of time. For pulling over, the membrane is placed squarely in the middle of the dialysis head. It is then pulled uniformly downwards, taking care to avoid creasing or folding the surface of the membrane. The membrane stretches sufficiently. The O-ring6 are now carefully rolled on from the direction of the tip of the dialyser head, over the membrane into the annular grooves 16, the membrane thereby being in a stretched condition. Excess membrane is then removed below the lower Ovine, whereafter the protective grid 23 is screwed on. In the case of comparatively long non-use, a rubber cap filled with a 0.1% sodium azide disinfection solution is pushed over the pro tective grid in order to avoid a drying out of the membrane. The membrane can be sterilised several times and, after a possible damaging, can be changed without difficulty. When assembling the immersion dialyser, the threads 20 and 27 are preferably sealed with the help of sealing materials and es specially with a polytetrafluoroethylene band. When the immersion dialyser is to be sterilised in an incorporated state, together with the fermenter, the membrane must be protected against bursting by the superimposition of pressure. This takes place by providing the inlet pipe 6 with a connection and con- necting the return pipe 7 with the fermenter chamber. In the case of sterilisation, the pressure on both sides of the membrane builds up equally strongly so that there is no danger of damaging the membrane. When sterilisation is finished and after the pressure has again been relieved, the superimposed pressure is removed, whereupon the immersion dialyser is, with the belp of tubes, again connected to the continuously operating analyser. Before the sterilisation, these tubes must be filled with liquid at the lowest plossible pump rate in order to prevent the formation of a pillow of air. The immersion dialyser according to the present invention can be sterilised not ody in a liquid but also with steam at a tem- perature of about 1200C. WHAT WE CLAIM IS:-

1. An immersion dialyser, comprising a dialysis head with a tip portion enclosed within a removable membrane stretched over it and mounted thereon, the head having a body with at least one inlet canal and a return canal; the head body being removably connected to a tubular member containing at least one inlet pipe removably connected with said inlet canal and a return pipe removably connected with said return canal; dosure means being provided for the tubular member.

2. An immersion dialyser according to claim 1, wherein the dialysis body has a flat end with a raised edge region to provide said tip portion over which the membrane is mounted.

3. An immersion dialyser according to claim 1, wherein the dialysis body has a fiat end to which a domed sieve is fitted to provide said tip portion over which the membrane is mounted.

4. An immersion dialyser according to claim 3, wherein the sieve is made of a metal or of a synthetic resin.

5. An immersion dialyser according to claim 1, wherein the dialysis head body has a coni- aallyeshaped tip provided with transverse and longitudinal grooves, said tip being enclosed by the membrane mounted thereon.

6. An immersion dialyser according to claim 1, wherein the dialysis head body has a rounded tip which is provided with a rounded base spiral groove running to the tip, said

spinal groove connecting the inlet canal with the return canal.

7. An immersion dialyser according to claim 6, wherein the spinal groove has thee ar four wiindings.

8. An immersion dialyser according to any of the preceding claims, wherein the dialysis head is made of a synthetic resin.

9. An immersion dialyser according to claim 8, wherein the synthetic resin is polytetra- fluoroethylene.

10. An immersion dialyser according to any of the preceding claims, wherein the membrane is held by one or more annular grooves, incorpcrated into the dialysis head, for the reception Of rubber O-rings.

11. An immersion dialyser according to any of the preceding claims, wherein the dialysis head has, for the tight connection with the tubular member, annular grooves on its rear end for the reception of sealing rubber Borings.

12. An immersion dialyser according to any of the preceding claims, wherein the inlet and return canals in the dialysis head are provided with threads into which can be screwed the inlet and return pipes.

13. An immersion dialyser according to any of the preceding claims, wherein the dialysis head has an outer thread for fixing a protective grid which is provided with a corresponding inner thread.

14. An immersion dialyser according to claim 13, wherein the protective grid is made of stainless steel.

15. An immersion dialyser according to any of the preceding claims, wherein the inlet and return pipes are made of stairlees steel.

16. An immersion dialyser according to any of the preceding claims, wherein the inlet and return canals and the inlet and return pipes have inner diameters of 0.5 to 3 mm.

17. An immersion dialyser according to any of the preceding claims, wherein the closure means is provided with tightly fitting pipe passages for the inlet and return pipes.

18. An immlension dialyser according to claim 17, wherein the closure means com- prises at least one annular groove for the reception of rubber 0-rings.

19. An immersion dialyser according to any of the preceding claims, wherein the tabular member is made from stainless steel.

20. An immersion dialyser according to claim 1, substantially as hereinbefore described and with reference to any of the Figures of the accompanying drawings.