BE1027735B1 - PROCEDURE FOR THE INSULATION OF METALS FROM MEDICAL DEVICES - Google Patents

Abstract

The present invention describes a method for isolating one or more metals from medical devices or parts thereof. More specifically, a method is described wherein medical devices containing one or more plastics and one or more metals are exposed to a mixture of at least one organic solvent and at least one cyclic ether so as to isolate the metals from the medical tools.

Description

' BE2020/5416

PROCEDURE FOR THE INSULATION OF METALS FROM MEDICAL TOOLS

TECHNICAL FIELD OF THE INVENTION The present invention describes a method for isolating one or more metals from medical devices. More specifically, a method is described wherein medical devices containing one or more plastics and one or more metals are exposed to a mixture of at least one organic solvent and at least one cyclic ether so as to isolate the metals from the medical tools.

BACKGROUND OF THE INVENTION Medical waste is an important part of today's waste chain. The medical waste from medical devices such as catheters, probes, implants, pacemakers or defibrillators is often further processed, or stored for many years in a specially provided landfill. This results in large amounts of waste of sometimes expensive yet recyclable materials. Many medical devices often contain valuable materials, such as metals, in addition to different types of plastics. For example, precious metals are often present in certain types of catheters. Although many parts of medical devices are in principle recyclable, until now they are usually not recycled for fear of contamination or because the recycling process would be too complex and expensive. However, this often results in valuable and recyclable materials, such as precious metals, being lost.

Due to the increased attention for the circular economy, there is also increased attention in healthcare for the separation of waste flows and the recycling of certain materials. In recent years, efforts have already been made to isolate metals from medical devices such as catheters or electronic probes, for example. However, these metals are isolated manually and mechanically, which means that these methods are not applicable on a large scale and are also much too time consuming. The present invention proposes a method in which one or more types of metals can also be isolated on a large scale and in a safe manner from medical devices consisting of one or more types of plastics. More in particular, with the current method, the metals can be isolated on an automated and also large scale, whereby the metals are also reusable afterwards. In addition

2. BE2020/5416, the current method also ensures decontamination and disinfection of the isolated metals, so that the obtained metals can also be considered safe, in contrast to the isolation method as described in CN 104 669 467.

SUMMARY OF THE INVENTION The present invention describes a method for isolating one or more kinds of metals from a medical device or part of a medical device, which contains one or more kinds of plastics and one or more kinds of metals and wherein the medical device or the part of a medical device is exposed to a mixture comprising at least one organic solvent and at least one cyclic ether. In a further embodiment, the organic solvent is a polar aprotic solvent. In yet a further Embodiment, the at least one organic solvent is selected from N,N-dimethylformamide, N-methylpyrrolidone, ethyl acetate, acetonitrile, dimethyl sulfoxide, propylene carbonate or a combination thereof. Even more preferably, the organic solvent is N,N-dimethylformamide. In yet another embodiment, the cyclic ether is selected from tetrahydrofuran, ethylene oxide, tetrahydropurane, pyran, or a combination thereof. In a still more specific embodiment, the cyclic ether is tetrahydrofuran. In yet a further specific embodiment, the at least one organic solvent is N,N-dimethylformamide and the at least one cyclic ether is tetrahydrofuran.

Thus, in a specific Embodiment, the present invention describes a method for isolating one or more kinds of metals from a medical device or part of a medical device containing one or more kinds of plastics and one or more kinds of metals, wherein the medical device or the part of it is exposed to a mixture of N‚N-dimethylformamide and tetrahydrofuran.

As already described above, in the present invention one or more metals are isolated from a medical device or a part thereof consisting of one or more plastics and one or more metals, by exposing the medical device or a part thereof to a mixture of at least one organic solvent, preferably at least one polar aprotic organic solvent, and at least one cyclic ether. In a further embodiment, the ratio of the at least one organic solvent and the at least one cyclic ether in the mixture ranges from 10:90 volume % to 90:10 volume %; preferably from 30:70 volume% to 70:30 volume%; even more preferably from 40:60 volume% to 60:40 volume%; even more preferably in a ratio of 50:50 volume %. In yet another embodiment, and when there are more than two different kinds of organic solvents and/or more than two different kinds of cyclic ethers present in the mixture, the ratio can vary even further, such as for example 10:10:40:50 volume% , 10:20:40:30 volume%, 10:30:30:30 volume%, 10:40: 40:10 volume%; 20:20:30:30% volume% or 30:30:20:20%.

3. BE2020/5416 In a further embodiment, the method according to the present invention comprises exposing a medical device or a component thereof to a mixture of at least one polar aprotic solvent and at least one cyclic ether; preferably wherein at least one polar aprotic solvent is selected from N,N-dimethyl! formamide, N-methylpyrrolidone, ethyl acetate, acetonitrile, dimethyl sulfoxide, propylene carbonate or a combination thereof, and preferably wherein at least one cyclic ether is selected from tetrahydrofuran, ethylene oxide, dioxane, tetrahydropurane, pyran, or a combination thereof, and wherein the polar aprotic solvent and the cyclic ether are present in the mixture in a ratio of 10:90 volume% to 90:10 volume%; preferably from 30:70 volume% to 70:30 volume%; even more preferably from 40:60 volume% to 60:40 volume%, even more preferably in a ratio of 50:50 volume%. In yet a further and specific embodiment, the method according to the present invention comprises exposing a medical device or a part thereof to a mixture of N‚N-dimethylformamide and tetrahydrofuran wherein the ratio of both solvents varies from 10:90 volume % to 90:10 volume%; preferably from 30:70 volume% to 70:30 volume%; even more preferably from 40:60 volume % to 60:40 volume %, even more preferably in a ratio of 50:50 volume %. The present invention thus describes the isolation of one or more types of metals from medical devices or parts thereof that contain one or more types of plastics and one or more types of metals.

In addition to these plastics and metals, the medical devices may also contain other materials, such as, for example, stainless steel.

In a further embodiment, the medical devices contain one or more plastics selected from rubber, polyester, polyethylene (PE), polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG), polytetrafluoroethylene (PTFE), polyisocyanurate, polymethyl methacrylate, prolypropylene (PP), polystyrene (PS), polyurethane (PUR), polyvinyl chloride (PVC), polycarbonate (PC), or combinations thereof.

In yet a further embodiment, the medical devices comprise polyethylene (PE), polytetrafluoroethylene (PTFE), or combinations thereof.

In another embodiment, the medical devices comprise one or more kinds of metals, more particularly one or more kinds of precious metals, selected from gold (Au), platinum (Pt), silver (Ag), rhodium (Rh), osmium (Os) , palladium (Pd), iridium (Ir), ruthenium (Ru), or tungsten (W); even more preferably, one or more precious metals selected from gold, platinum or palladium.

In yet another embodiment, other metals such as copper (Cu) or Aluminum (AI) can also be isolated by the present method.

In yet another and specific embodiment, the present method is suitable for isolating metals such as gold, platinum, silver, palladium, copper, aluminum, or a combination thereof from medical devices.

In yet a further embodiment, the medical devices further comprise one or more

4- BE2020/5416 other components, such as stainless steel (SS). Thus, for example, the medical devices may consist of a number of plastics, such as PE and/or PTFE, stainless steel, and one or more metals, such as gold, palladium, platinum, copper or aluminum.

As already described above, the present invention describes a method for isolating one or more metals from medical devices or parts thereof. These medical devices include all medical devices that contain one or more metals and one or more plastics. In addition, these medical aids can of course also contain other materials, such as stainless steel. In a further embodiment, these medical devices are preferably medical devices used in diagnostics, imaging or therapeutic purposes. In another specific embodiment, these medical devices are selected from catheters, probes, implants, pacemakers, defibrillators; preferably catheters. The method in all its aspects of the present invention is also applicable to isolating one or more kinds of metals from a part or a part of a medical device. In addition to exposure to a mixture comprising at least one organic solvent and at least one cyclic ether, in the method according to the present invention the medical device or a part thereof can also be exposed to ultrasonic waves. This exposure can occur simultaneously when the medical device or part thereof is exposed to the mixture of at least one organic solvent and at least one cyclic ether. For example, the ultrasonic waves can be passed through this mixture, whereby the medical device or part thereof is then immersed in the mixture. In yet a further embodiment, the frequency of the ultrasonic waves is at least 10 kHz; preferably at least 20 kHz. The present invention describes a method in which a medical device or part thereof is exposed to a mixture of at least one organic solvent and at least one cyclic ether according to all possible embodiments as described above. In a specific embodiment, the medical device or component thereof will be exposed for at least 5 minutes to the mixture comprising at least one organic solvent and at least one cyclic ether. In yet a further embodiment, exposure to this mixture will last between 5 and 30 minutes; more specifically between 5 and 15 minutes. As already mentioned above, when the medical device or part thereof is exposed to the mixture, an exposure to ultrasonic waves can also take place simultaneously, more in particular ultrasonic waves of at least 10 kHz; preferably at least 20 kHz.

The method according to the various embodiments of the present invention is also typically characterized by the fact that the isolated metals are free from contamination by bacteria, viruses or other organisms. In a further aspect, the present invention thus describes a method as described above, said method comprising the following steps: - exposing the medical device or a part thereof to the mixture of at least one organic solvent and at least one cyclic ether for at least 5 minutes; - optionally exposing the medical device or a part thereof to ultrasonic waves whose frequency is at least 10 kHz and wherein the ultrasonic waves are passed through the mixture of at least one organic solvent and at least one cyclic ether; - removing the released metal from the mixture of at least one organic solvent and at least one cyclic ether. - optionally reusing the mixture of at least one organic solvent and at least one cyclic ether. In yet another aspect, the present invention also includes a metal isolated from a medical device as described above and by a method as also described above. In a further aspect, this metal is free from contamination by bacteria, viruses, or other organisms.

DETAILED DESCRIPTION OF THE INVENTION The present invention proposes a method for isolating one or more kinds of metals from a medical device. More specifically, this method comprises exposing the medical device, consisting of one or more kinds of plastics and one or more kinds of metals, to a mixture comprising one organic solvent and at least one cyclic ether. The inventors of the present invention established that by exposure to the mixture of at least one organic solvent and at least one cyclic ether, all plastic parts of a medical device or a part thereof were dissolved, so that the metal parts can be easily isolated. This method thus makes it possible to isolate the metals on a large scale and without any form of mechanical intervention from a medical device or part of a medical device, such as catheter, probes, pacemakers, defibrillators, or implants. More particularly, the present method is suitable for isolating metals from catheters, such as e.g. cardiac catheterization catheters (cath lab), or portions or components of catheters. In addition, the current method is also particularly suitable for the isolation of metals from pacemakers, pacemaker parts, defibrillators and defibrillator parts. In particular, with the current method, metal rings, metal contacts or other

G-BE2020/5416 metal-containing parts from pacemakers and defibrillators are isolated. More specifically, the current method allows metal parts to be isolated from the wiring sections of pacemakers and defibrillators.

The current invention thus offers a solution for recycling precious metals from medical devices or from parts or components of medical devices. Many medical devices often contain precious precious metals in addition to different types of plastics. For example, precious metals are often present in certain types of catheters. Although many components of medical devices are in principle recyclable, they are currently mostly not recycled for fear of contamination or because the recycling process would be too complex and expensive. However, this often means that precious and recyclable materials, such as precious metals or other metals, are lost.

As can be seen from the examples, the mixture of at least one organic solvent and at least one cyclic ether, and in particular the mixture of N,N-dimethylformamide and tetrahydrofuran, ensures that the plastic parts of the medical device such as a catheter or part of a catheter, go into solution, allowing the remaining metal to be easily isolated. As can also be seen from the examples, any ratio of organic solvent and cyclic ether in the mixture, such as e.g. a mixture of N,N-dimethylformamide and tetrahydrofuran, is effective, such as e.g. a ratio of 90:10 volume %, 80 :20 volume%, 70:30 volume%, 60:40 volume®%, 50:50 volume%, 40:60 volume%, 30:70 volume®%, 20:80 volume%, 10:90 volume®%. In a further specific Embodiment, there is no water present in the mixture of at least one organic solvent and at least one cyclic ether. Namely, the inventors found that this decreased the activity of the mixture.

The method according to the present invention thus offers the advantage that no mechanical intervention or heating to very high temperatures (0.a. 1700°C) is required, and that the exposure to the mixture of at least one organic solvent and at least one cyclic ether in all its embodiments is sufficient to isolate the metals from the medical device or part of a medical device. The plastics present are brought into solution in the mixture, so that the metal can be isolated. Thus, no manual action is required to separate the metal from the rest of the medical device. The current method therefore offers a very great advantage because the isolation of metals from medical devices or parts thereof can be done fully automated and on a large scale, and that no mechanical or manual intervention is necessary. According to the present method, the medical device or part thereof can simply be immersed in the mixture of at least one organic solvent and at least one cyclic ether, after which the plastics present go into solution in the mixture. After a short time of exposure to the mixture, e.g. between 5 and 10 minutes, the released

7- BE2020/5416 metals can then be easily isolated from the mixture. This isolation can be done eg by certain filtering techniques or by a scan performed by eg an automated robot. In addition, the exposure of the medical device or part thereof to the mixture of at least one organic solvent and at least one cyclic ether ensures that the metal obtained is completely free from contamination by viruses, bacteria or other organisms. As can be seen from the examples, an exposure of 5 to 10 minutes to the mixture of at least one organic solvent and at least one cyclic ether is already sufficient to isolate the metals. On the other hand, this exposure time does not have to be limited, it can of course also last longer.

In addition, it was also found that the mixture of at least one organic solvent and at least one cyclic ether is reusable several times, up to at least 75 times, which also offers an important ecological and economic advantage.

It was also found that the mixture of at least one organic solvent and at least one cyclic ether ensures that the metals obtained are completely free of viruses and bacteria, thus ensuring decontamination of the metals obtained. As a result, the obtained metals can be recycled and reused easily and without any risk of contamination.

As already described above, the medical devices in the present method can be all kinds of medical devices containing one or more kinds of plastics and one or more kinds of metals, such as e.g. catheters, probes, electronic probes, pacemakers, defibrillators, implants; and more specifically catheters, such as eg kathlab catheters. These medical devices may also have already been used on or in the patient. The current method and exposure to the mixture of at least two organic solvents also ensures that all viruses, bacteria and other contaminating substances present are killed. As a result, after the current method there is no risk of contamination if the isolated metals are reused.

The medical devices can also be expired products that were never used on the patient. As a result, the current invention ensures that parts of expired medical devices can still be recycled and reused.

EXAMPLES Example 1: Composition of the mixture of at least one organic solvent and at least one cyclic ether In this example, different ratios of a mixture of N,N-dimethylformamide and tetrahydrofuran were evaluated. N,N-dimethylformamide and

8- BE2020/5416 tetrahydrofuran mixed in a volume ratio of 90:10 volume%, 80:20 volume%, 70:30 volume%, 60:40 volume%, 50:50 volume%, 40:60 volume%, 30: 70 volume%, 20:80 volume% and 10:90 volume%. A section of a catheter of approximately 1 cm length consisting of polytetrafluoroethylene (PTFE), stainless steel, aluminum and copper was immersed and thus exposed to the different types of mixtures of N,N-dimethylformamide and tetrahydrofuran (Table 1). In each case the time was measured within which the PTFE was completely dissolved in the mixture and during which the metal could be isolated. Table 1 shows that isolating the metal from the catheter is possible for all types of mixtures and that the time of exposure to the mixture varies between 6 minutes and 10 minutes.

In addition, it is also clear from this test that any ratio of N,N-dimethylformamide with tetrahydrofuran allows to dissolve the PTFE and isolate the metal. Table 1: Effect of the ratio between the organic solvent and the cyclic ether Ratio N,N-dimethyl! formamide : | Time to isolation of the metal and (EE Example 2: Stability of the process IN a further example, the stability of the process of the present invention was determined evaluating how much variability exists in the time required to isolate the metal from a section of a 1 cm long catheter consisting of polytetrafluoroethylene (PTFE), stainless steel, aluminum and copper. For this, 10 different pieces of catheters of equal size (1 cm) and weight were exposed to the same mixture of N,N-dimethylformamide and tetrahydrofuran, namely a mixture with a 50:50 volume % ratio of N,N-dimethylformamide and tetrahydrofuran As shown in Table 2, the metal present at each catheter could be isolated after 6 to 7 minutes, and this time was also stable within the 10 different pieces of catheter.

_9- BE2020/5416 Table 2. Stability of the method Port van hama Example 3: Effect of ultrasonic waves In another example, the effect of ultrasonic waves on the isolation of the metal from a catheter was evaluated. Hereby 3 different pieces of catheters of equal size (1 cm) and weight and consisting of polytetrafluoroethylene (PTFE), stainless steel, aluminum and copper exposed to the same mixture of N,N-dimethylformamide and tetrahydrofuran, namely a mixture with a 50:50 volume % ratio of N,N-dimethylformamide and tetrahydrofuran. In addition, during the process, the mixture was placed in an ultrasonic bath, wherein the catheter pieces were exposed to the mixture of N,N-dimethylformamide and tetrahydrofuran, and to ultrasonic waves at a frequency of 40 kHz. The time needed to isolate the metals from the catheter was measured in each case. After 1 and 2 minutes it could be determined that 50% of the plastics present in the catheters had already dissolved, and after 3 minutes all plastics had completely dissolved and the metals (copper and aluminum) could be isolated. Thus, compared to the time measured in Example 2, the isolation of metals in the presence of ultrasonic waves was much faster. Example 4: Removal of bacteria and viruses The method of the present invention also ensures that the isolated metals are free from contamination by bacteria, viruses or other organisms because the mixture of at least one organic solvent and at least one cyclic ether ensures that all viruses, bacteria and other organisms present on the medical device are killed or inactivated.

In this example, several dip slides (Contact slide, TSA+ neutralizing / Rose Bengal Agar, VWR Chemicals) were exposed to air, saliva, urine and blood at a temperature of 25°C, with or without a mixture containing a 50: 50 volume% ratio of

-10- BE2020/5416 N,N-dimethylformamide and tetrahydrofuran. Dipslides exposed to air, saliva, urine or blood only showed clear signs of growing fungi, yeasts and/or bacteria after 24 hours. After 24 hours, a drop of the mixture with a 50:50 volume % ratio of N,N-dimethylformamide and tetrahydrofuran as described in this invention was then applied to the dipslides, and the growth of bacteria, fungi and yeasts was evaluated after 4 days. . No or negligible growth of bacteria, fungi and yeasts was found in the dipslides exposed to the mixture according to the present invention. The dipslides that were not exposed to the mixture according to the current findings showed a very strong growth of bacteria, molds and yeasts.

Table 3: Removal of Fungi, Bacteria and Yeast Dipslide Exposure to | Growth of | Growth of | Growth of mixture of N,N- | yeast fungi | bacteria dimethylformamide/ tetrahydrofuran Exposed to | No No Yes No me OUT OT OT Exposed to | Yes No No No me EE OT TT Exposed to blood | No No No Yes (SA Exposed to blood | Yes No No No eam OTT OT Example 5: Isolation of Platinum from pacemakers This example attempted to isolate one or more metals (especially Platinum) from different types of pacemakers. The following types of pacemakers were tested: Vitatron Diamond II, Guidant Discovery II and Vitatron T7ODR More specifically, the part of these pacemakers that leads the wires and conductors to the heart is insulated and exposed to a mixture of N,N-dimethylformamide and tetrahydrofuran, namely a mixture with a 50:50 volume % ratio of N,N-dimethylformamide and tetrahydrofuran After 12 hours exposure to the mixture, the small Platinum parts, such as rings and contacts, could be isolated and the rest of the plastic material had dissolved.

Claims (16)

-11- BE2020/5416 CONCLUSIONS 1. Method for isolating one or more types of metals from a medical device or part of a medical device containing one or more types of plastics and one or more types of metals and wherein the medical device or part thereof is exposed to a mixture comprising at least one organic solvent and at least one cyclic ether, whereby the one or more kinds of metals are released from the medical device or portion thereof, and wherein the organic solvent is N,N-dimethyl formamide. The method of claim 1 wherein the organic solvent is a polar aprotic solvent. The method according to claim 1 or 2 wherein the organic solvent is selected from N,N-dimethylformamide, N-methylpyrrolidone, ethyl acetate, acetonitrile, dimethyl sulfoxide, propylene carbonate or a combination thereof. The method of any preceding claim wherein the cyclic ether is selected from tetrahydrofuran, ethylene oxide, dioxane, tetrahydropurane, pyran, or a combination thereof. The method of claim 4 wherein the cyclic ether is tetrahydrofuran. The method according to any one of the preceding claims wherein the ratio of the organic solvent and the cyclic ether in the mixture ranges from 10:90 volume% to 90:10 volume%; preferably from 30:70 volume% to 70:30 volume%; even more preferably from 40:60 volume% to 60:40 volume%. The method of any preceding claim wherein the plastics are selected from rubber, polyester, polyethylene (PE), polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG), polytetrafluoroethylene (PTFE), polyisocyanurate, polymethyl methacrylate, prolypropylene (PP), polystyrene ( PS), polyurethane (PUR), polyvinyl chloride (PVC), polycarbonate (PC), or combinations thereof. The method of any preceding claim wherein the plastics are selected from polyethylene (PE) and polytetrafluoroethylene (PTFE) or combinations thereof. The method of any preceding claim, wherein the metals are selected from gold (Au), platinum (Pt), copper (Cu), aluminum (AI), silver (Ag), and palladium (Pd). 12- BE2020/5416 The method of any preceding claim, wherein the medical device comprises one or more other components. The method of any preceding claim wherein the medical device or part thereof is exposed for at least 5 minutes to the mixture comprising at least one organic solvent and at least one cyclic ether. The method of any preceding claim, wherein the medical device or part thereof is additionally exposed to ultrasonic waves. The method of claim 13, wherein the frequency of the ultrasonic waves is at least 10 kHz. The method of any preceding claim wherein the medical device is selected from catheters, probes, implants, pacemakers or defibrillators. The method of any preceding claim wherein the one or more released metals are free from contamination by bacteria, viruses or other organisms. The method according to any one of the preceding claims, comprising the steps of: - exposing the medical device or a component thereof to the mixture of at least one organic solvent and at least one cyclic ether for at least 5 minutes; - optionally exposing the medical device or a part thereof to ultrasonic waves with a frequency of at least 10 kHz and wherein the ultrasonic waves are passed through the mixture of at least one organic solvent and at least one cyclic ether; - removing the released metal from the mixture of at least one organic solvent and at least one cyclic ether. - optionally reusing the mixture of at least one organic solvent and at least one cyclic ether.