This invention relates to a method for making peracetic acid and apparatus for making peracetic acid solution using the method. The invention relates particularly but not exclusively to a method and apparatus for making peracetic acid solutions for use as a sporicidal, bactericidal, fungicidal and virucidal disinfectant or sanitising composition. Such compositions may be used in sanitising or disinfection of surfaces and clinical devices in hospitals or other locations in which control of infectious microorganisms is imperative. Preferred embodiments of the invention relate to compositions having sporicidal, bactericidal, fungicidal and virucidal activity and for disinfection of biofilms.

EP3094177 discloses a solid disinfectant dosage form comprising tetra acetyl ethylenediamine (TAED), a peroxy compound selected from the group consisting of: sodium percarbonate, ammonium persulphate, calcium percarbonate, magnesium percarbonate, sodium persulphate and mixtures thereof; a colour indicator system; and a buffer; wherein the addition of the dosage form to a predetermined quantity of water produces a disinfectant solution containing peracetic acid in an active concentration of at least 4000 ppm; wherein the ratio of TAED to the peroxy compound is 55-65: 100 wt%; wherein the colour indicator comprises a first non-mordant dye having a first colour and being bleachable after a first dye lifetime of 0.5 to 10 minutes in a test solution at 20°C to 40°C and pH 8.0 to 8.5 containing 0.05 wt% to 0.15 wt% of the dye and 45 wt% to 55 wt% of sodium percarbonate; and a second non-mordant dye having a second colour different from the first colour and bleachable after a second dye lifetime of not less than 24 hours in the test solution; wherein the second colour provides a visual indication that the active concentration of peracetic acid is at least 4000 ppm; and wherein bleaching of the second dye indicates that the concentration of peracetic acid is below 4000 ppm.

Such a dosage form may provide a convenient clock system to give a visual indication of the time- lapse following activation of the disinfectant components, so that a user can know that the solution has a sufficient level of sporicidal or other biocidal activity. The clock system gives a multi-coloured display analogous to a traffic light display.

US10300162 discloses a disinfectant wipe dispenser comprising a container having first and second compartments, the first compartment being a dimension to store a supply of wipes and separated by a buffer including one or more channels communicating between the compartments. The first compartment has an outlet through which wipes may be successively withdrawn and the second compartment is a dimension to receive one or more portions of a disinfectant composition comprising a peroxy activator, a peroxy compound and optional further excipients selected so that addition of the dosage form to a predetermined quantity of water produces a disinfectant solution containing peracetic acid at a concentration of at least 100 ppm. The channels communicate between the compartments and allow flow of water or pre-prepared peracetic acid solution and aqueous disinfectant but prevent movement of particulate disinfectant sediment from the second to the first compartment.

According to a first aspect of the present invention peracetic acid disinfectant solution making apparatus comprises: a vessel configured to hold water or an aqueous disinfectant solution; a receptacle dimensioned to receive and hold a multiplicity of solid dosage forms, wherein the dosage forms are formulated to provide a peracetic acid containing disinfectant solution upon contact with water; wherein the receptacle comprises: an upper end, a lower end and an interior compartment extending between the upper and lower ends, the interior compartment being dimensioned to receive the solid dosage forms; and an exterior communicating with an interior of the vessel; the receptacle including one or more apertures located at or adjacent the lower end, the apertures communicating between the interior and exterior of the receptacle, a dimension of the or each aperture being configured to permit a flow of peracetic acid solution from the vessel into the receptacle and a flow of disinfectant solution from the receptacle into the vessel; the vessel having a predetermined minimum level of water or disinfectant solution; a support for the receptacle configured so that when the receptacle is engaged with the support, the lower end of the receptacle is located in the vessel with the one or more apertures located below the predetermined minimum level of water or disinfectant solution.

The receptacle may be located in the vessel in use and arranged so that water contained in the vessel may pass through the apertures into the receptacle to contact a dosage form located at the lower end of the receptacle.

The receptacle may be arranged so that the interior extends generally upwardly, preferably generally vertically in use. The receptacle may have an upwardly facing opening which may be closed by a cap or other closure in use. The opening may be configured to permit dosage forms to be inserted through the opening into the receptacle.

The receptacle may be elongate and configured to be located in a vertical or otherwise generally upright orientation in the vessel in use. The receptacle may be otherwise oriented, for example inclined to the vertical. The receptacle may have an elongate interior with a cross sectional configuration adapted to successively receive a plurality of dosage forms, to form a stack of tablets.

The receptacle preferably forms a sealed enclosure for the dosage forms so that air or water may only pass into or out of the receptacle through the apertures. The closure preferably provides an airtight seal to the receptacle.

In use of the apparatus, the receptacle is located within the reservoir or vessel, the apertures being located beneath the surface of water or disinfectant solution. Increased pressure of air as water rises within the receptacle prevents the water or solution from rising excessively within the receptacle so that only one or more of the lowermost dosage forms are contacted with the water or solution and allowed to dissolve. In this way, only the lowermost dosage form or forms can dissolve at a time, releasing peracetic acid into the water or solution. The lowermost dosage form may dissolve first. This achieves control of the release of peracetic acid into the vessel, allowing control of the concentration of peracetic acid in the reservoir or vessel, to maintain the concentration within a desired range, for example 500 to 5,000 ppm, preferably 1,000 to 4,000 ppm, for a prolonged period of 24 hours or longer. The dosage forms may comprise tablets, granules, lozenges or other solid forms. Use of tablets is preferred to facilitate control of the flow of water to the dosage stack. The receptacle may be cylindrical, square or rectangular in cross-section, having a diameter or cross-sectional width and depth to slidingly receive a stack of circular or cylindrical dosage forms, particularly tablets.

A support may be provided to receive and hold the receptacle during use. The support may comprise an upwardly opening tube engaged with and extending downwardly from a lid of the vessel. A lower end of the support may have one or more openings to permit water or peracetic acid solution to flow through the support and through the apertures into the receptacle. The receptacle may be removable by opening a cover, for example a hinged cover in the lid. Alternatively, the cover may be removable and the support detached from the lower side of the cover to allow removal and replacement of the receptacle and dosage forms therein.

The interior and exterior of the receptacle may be separated by a water- and air-impermeable wall or barrier.

In use of the apparatus a number of tablets or desired total weight of the dosage forms are placed in a stack in the receptacle. The receptable is then mounted in the aperture in the lid for the reservoir. The reservoir is filled with water to a level between the predetermined maximum and minimum levels. The levels may be indicated by indicia or other markings on the side of the reservoir or vessel. Initially, one or more tablets may be dissolved directly in the water to generate a required starting concentration of peracetic acid in the solution. The initial dosage forms may be located in a separate compartment communicating with the reservoir. For example, a removable cartridge containing the initial dosage forms may be provided. This cartridge may be perforated, provided with apertures or may be water-permeable, and may be arranged to be inserted into the reservoir to provide the starting concentration of peracetic acid. The cartridge may be removed when the dosage forms therein have been exhausted. The cartridge may then be recharged with fresh dosage forms for subsequent reuse.

Alternatively, the reservoir may be filled with a pre-prepared peracetic acid solution having a desired initial concentration of peracetic acid. A roll of wipes may be placed in the vessel with a first wipe inserted through the opening in the lid. After a period of equilibration, for example, 15 minutes, the wipes may be withdrawn sequentially through the opening for use. Alternatively, one or more wipes can be added to a pre-prepared solution, or a pre-prepared solution can be poured onto the wipe or wipes.

In a preferred embodiment, a cylindrical roll of wipes is placed horizontally in the vessel in use. This allows the outermost wipes to be saturated with the solution before their withdrawal from the vessel.

Use of a vertically arranged roll of wipes is less preferred because wipes drawn from the axial portion of the roll may not have been saturated with solution by diffusion from the exterior of the roll.

When the cap is closed, the receptacle is preferably airtight with the exception of the apertures. The flow of liquid into or out of the receptacle is controlled by gas pressure within the receptable, preventing the reservoir filling with water and consequential dissolution of an excessive number of dosage forms.

The dimensions of the or each aperture, for example, the cross-sectional area, may be selected to control the rate of passage of water from the reservoir into the receptacle and the rate of passage of peracetic acid solution from the receptacle into the reservoir. This allows the rate of dissolution of the dosage forms to be controlled.

The distance between the dosage forms and the inner wall of the receptacle may be about 1.5 mm. The provision of a narrow gap between the dosage form and receptacle, particularly a cylindrical or parallel-sided tablet, controls the flow of water past the lowermost dosage form until the lowermost dosage form has at least partially broken down, disintegrated or dissolved.

In such an embodiment, the receptacle may be provided with a pressure release valve or aperture configured to allow release of excessively high pressure within the receptacle. High pressure may be caused by blockage of the receptable by a tablet swollen by contact with moisture. In a preferred embodiment, between 1 and 8 apertures may be provided, for example, 1 to 4 apertures. Each aperture may be circular having a diameter from 1 to 7mm.

In a preferred embodiment, the total cross-sectional area of the or each of the apertures is selected so that the peracetic acid concentration in the reservoir is maintained at a constant value during use of the apparatus. The total area of the aperture or apertures may be adjusted by partially, or wholly blocking one or more of the apertures.

In an alternative embodiment, a slidable closure member may be moved between two or more locations to provide a desired peracetic acid concentration in use.

Indicia may be provided on the wall of the reservoir to indicate locations of the minimum and maximum predetermined water or solution levels.

Alternatively, the receptacle may have two or more interchangeable lower end caps, each cap having a number and/or size of aperture or apertures selected to provide a required peracetic acid concentration. The receptacle may be cylindrical having an open end or mouth, the end cap being engageable to close the opening so that water or peracetic acid solution may only pass into and out of the receptacle through the one or more apertures.

The end cap may be rotated relative to the receptacle to adjust the area of the aperture or apertures.

The area of the aperture or apertures required to provide a desired peracetic acid concentration may be determined empirically by a user to accommodate the conditions of use, for example, the ambient temperature, water temperature, frequency of withdrawal of wipes from the reservoir or rate of dispensing of disinfectant solution from the reservoir.

Alternatively, in a preferred embodiment, the one or more settings for the aperture or apertures are determined by the manufacturer and the apparatus calibrated so that the apparatus as provided to a user is ready for use. The maximum dimension of the aperture may be a fully opened configuration.

The minimum dimension of the aperture may be a fully closed configuration preventing flow of water through the aperture.

Adjustment means may be provided for adjustment of a dimension of the aperture between a maximum dimension and a minimum dimension. Adjustment means may be provided on the exterior of the receptacle, for example, a rotatable or slidable knob or other member. The adjustment means may be manually movable to adjust the dimension of the aperture. A scale may be provided with indicia to give a visual indication of the degree of opening of the aperture. A scale may include a display of numbers or letters or colour coded portions, for example, visible through a second aperture in the of the wall of the receptacle.

The receptacle may have a planar, concave or convex base. The one or more apertures may be located in the base or in the wall adjacent the base.

The apertures may be arranged so that water or solution passing through the or each aperture into the receptacle may contact the lowermost tablet or other dosage form in a stack of tablets or dosage forms.

In an embodiment, the dimension or diameter of the interior of the receptacle is selected so that water or solution passing through the aperture into the receptacle may only contact the lowermost dosage form, for example, the bottom tablet in a stack of tablets. This may enable the dosage forms to dissolve sequentially with the lowermost tablet dissolving first, thereby controlling the rate of generation of peracetic acid in use.

A collector may be provided at a lower region of the reservoir for collecting solid material resultant from disintegration and dissolution of the dosage forms. The collector may be a sponge, cloth or other absorbent material located at or adjacent the bottom of the reservoir. Alternatively, a perforated screen may be provided with apertures through which particulate material may fall for collection in a lower part of the reservoir. Alternatively, or in addition, a collector may be provided at the bottom of the receptacle arranged to collect solid matter falling from the tablets or dosage forms as they dissolve.

Alternatively, or in addition, a filter may be provided to remove particulate matter from the solution before use. The filter may extend across the base of the reservoir, for example being supported in spaced relation above the base to provide a cavity beneath the filter for collection of particles resultant from disintegration of the dosage forms.

In an embodiment, the apertures of the receptacle may be located in the cavity beneath the filter in use. In this arrangement, any particles passing from the receptacle are retained beneath the filter.

Apparatus in accordance with a first aspect of the present invention confers the advantage of increasing the period during which a peracetic acid solution having a required concentration of peracetic acid may be provided. Conventional peracetic acid solutions may be depleted and therefore not safely usable after a period of 24 hours. Apparatus in accordance with the present invention can provide a solution which maintains a required working concentration of peracetic acid for a period of up to 5 days, preferably up to 10 days for normal health care uses. The receptacle may be configured to hold a number of dosage forms, for example, up to 50 tablets in order to provide a desired working lifetime for the apparatus.

The dosage forms may be manufactured in accordance with EP3094177 or US10300162 the disclosures of which are incorporated into the present specification by reference, for all purposes.

Apparatus of the present invention has the advantage that the solution in the reservoir may be maintained at an approximately constant peracetic acid concentration throughout the duration of use, for example, up to 3 days, preferably up to 10 days or until the supply of dosage forms in the reservoir is exhausted.

According to a second aspect of the present invention, a method of making a peracetic acid solution comprises the steps of: providing an apparatus in accordance with the first aspect of the present invention; placing a predetermined quantity of a solution with a peracetic acid concentration within a required range in the vessel; placing a plurality of dosage forms in a stack within the receptacle; inserting the receptacle into the solution; the reservoir and dosage forms being arranged so that solution passing through the aperture or apertures may only contact a lower-most dosage form of the stack; wherein the peracetic acid concentration in the solution remains within a required concentration range of 500 to 5,000ppm, preferably 1,000 to 4,000ppm, throughout the duration of use of the apparatus.

The initial solution may be obtained by placing a predetermined quantity of water in the reservoir and dissolving one or more dosage forms in the water.

Alternatively, a peracetic acid solution may be prepared externally and added to the reservoir to provide an initial solution with a peracetic acid concentration within a required range.

The duration of use may be at least 2 days, preferably at least 5 days, more preferably at least 8 days, most preferably at least 10 days.

The peracetic acid concentration may be determined by a colour change of the solution or by instrumental analysis.

An important feature of the present invention is that the passage of water and/or solution through the aperture or apertures into the receptacle controls dissolution of the dosage forms and passage of the fresh peracetic acid-containing solution with a higher concentration of peracetic acid through the apertures into the reservoir. This serves to maintain the peracetic acid concentration in the reservoir in the required range.

The peracetic acid concentration may be maintained at a value within a required range without need to adjust the composition of the dosage forms or the dimensions or area of the aperture or apertures. For example, if a required peracetic acid concentration is 2,000ppm, the reservoir may be filled with water up to a level indicated by a marking on the reservoir wall. A number of dosage forms, sufficient to provide a peracetic acid concentration of 2,000ppm are placed in the water and allowed to dissolve. The receptacle containing a stack of tablets or other dosage forms is then placed in the receptacle so that the aperture or apertures are located below the surface of the solution.

The apparatus may then be used by withdrawing wipes from the solution for use or by dispensing portions of the solution onto a sponge or other absorbent material or directly onto a surface to be disinfected.

If a different peracetic acid concentration is required, for example, 4,000ppm, the reservoir may be filled with water or pre-prepared peracetic acid solution up to the level indicated on the wall as before, and a higher number of dosage forms dissolved in the water to give an initial peracetic acid concentration of 4,000ppm. The receptacle is filled with tablets and inserted into the solution as before. The apparatus is then used in the same manner as before. The peracetic acid concentration remains at the 4,000ppm level during use of the apparatus over a period of up to 5 days.

Surprisingly, the same receptacle and tablets may be used to maintain a working peracetic acid concentration of a solution within a range of initial peracetic acid concentration values, for example, 500 to 5,000ppm, for example 1,000 to 4,000ppm, without the need to adjust the composition of the dosage forms.

In embodiments the dosage form comprises: a peroxy activator; a peroxy compound; a colour indicator system; and a buffer, and optional excipients.

In embodiments the dosage form comprises a peroxy compound selected from the group consisting of: sodium percarbonate, ammonium persulphate, calcium percarbonate, magnesium percarbonate, sodium persulfate, and mixtures thereof; a colour indicator system; and a buffer; wherein the addition of the dosage form to a predetermined quantity of water produces a disinfectant solution containing peracetic acid in an active concentration of at least 500 ppm, preferably at least 4000ppm.

In embodiments, the dosage form comprises a colour indicator. In embodiments the colour indicator comprises a first non-mordant dye having a first colour and being bleachable after a first dye lifetime of 0.5 to 10 minutes in a test solution at 20°C to 40°C and pH 8.0 to 8.5 containing 0.05wt% to 0.15wt% of the dye and 45wt% to 55wt% of sodium percarbonate; and a second non-mordant dye having a second colour different from the first colour and bleachable after a second dye lifetime of not less than 24 hours in the test solution; wherein the second colour provides a visual indication that the active concentration of peracetic acid is at least lOOOppm, more preferably 4000ppm; and wherein bleaching of the second dye indicates that the concentration of peracetic acid is below lOOOppm.

The dosage form in use may provide a clock system to give a visual indication of the time elapsed following activation of the disinfectant components, so that a user can know that the solution has a sufficient level of sporicidal or other biocidal activity. The clock system gives a multi coloured display analogous to a traffic light display. In a preferred embodiment the first colour is purple, the dosage form producing a purple-coloured solution when dissolved in water, the purple colour being bleached within the first lifetime when the desired concentration of peracetic acid, preferably 2,000 ppm is reached.

The first indicator has a first dye lifetime before bleaching of 0.5 to 10 minutes, preferably of 2 to 10 minutes, more preferably 2 to 7 minutes, most preferably 2 to 4 minutes.

After bleaching of the first colour, the second colour, which may be red or pink in a preferred embodiment, remains visible. The maintenance of the pink colour provides a visual indication that the solution was prepared within a predetermined time interval, for example 24 hours, during which the solution will remain at the active concentration of 4000ppm or greater. The indicator provides a visual signal that the solution was prepared within a sufficiently short time period that the desired activity has not been lost. At a concentration of peracetic acid of 4,000ppm or more the solution is sporicidal within a contact time of 15 to 30 seconds. This provides a solution which may be used to disinfect surfaces by spraying and/or wiping before the surfaces can dry due to evaporation.

In an optional but preferred embodiment in which a third indicator is used, when the second, typically red or pink indicator is bleached after 24 hours in the preferred example, the third indicator may be observed. The lifetime of the third indicator is of not less than 36 hours. In a preferred embodiment of the invention, a third indicator is yellow or orange. When the third indicator has been bleached the solution is spent and can be discarded.

During the use of the dosage form, a solution in water may change from the colours purple, followed by pink, followed by orange, or yellow, before becoming colourless.

Preferably the colour of the second indicator is darker and masks the colour of the third indicator. The first indicator may be further darker to mask both of the second and third colours before it is bleached.

The second colour may be pink or red.

The third colour signal may be a change from a colour, for example red or yellow, to colourless.

The system may be arranged so that the third colour of the standing solution which indicates a peracetic acid concentration of or greater than 4000ppm or more, is maintained for at least 24 hours at ambient temperature.

The amount of peroxy compound may be from 1 lwt% to 80wt% of the solid dosage form, preferably 30wt% to 55wt%, more preferably 35wt% to 55wt%, most preferably 30wt% to 50wt%. Percentages or other amounts referred to in this specification are by dry weight unless indicated otherwise and are selected from any ranges quoted to total 100%.

The peroxy compounds are selected from the group consisting of: sodium percarbonate, ammonium persulphate; calcium percarbonate; magnesium percarbonate; sodium persulfate and mixtures thereof.

Sodium percarbonate is particularly preferred and has favourable health and environmental properties.

A pH modifier or buffer is employed. The pH modifier may comprise a couple comprising sodium bicarbonate and anhydrous organic acid. This may be powdered or granular. The pH modifier may be one or more of citric acid, fumaric acid, tartaric acid and adipic acid. Anhydrous adipic acid is preferred.

The dosage form may be provided in the form of a tablet, for example, a compressed tablet or lozenge. An effervescent couple may be employed to facilitate dissolution.

A disintegrant may be employed, for example polyvinyl pyrrolidone.

Alternatively, the dosage form may be provided as a powder contained in a capsule, sachet, pouch or other container. The container may be formed from a water soluble material, for example, polyvinyl alcohol. An example of a suitable water soluble thermoplastic film is Monosol® M8900.

The invention will be further described by means of example but not in any limitative sense, with reference to the accompanying drawings, of which:

Figure 1 shows an apparatus in accordance with this invention;

Figure 2 shows an apparatus similar to Figure 1;

Figure 3 shows a further apparatus; Figure 4 shows the apparatus including a cartridge with a dosage form for generating the initial concentration of peracetic acid;

Figure 5 shows an alternative apparatus in which the receptacle is retained within a support;

Figure 6 shows removal of the receptacle from the support;

Figure 7 shows insertion of a receptacle with fresh dosage forms;

Figure 8 shows the fresh dosage forms inserted into the support, and Figure 9 shows apparatus including an absorbent layer.

The apparatus shown in Figure 1 comprises an upwardly opening vessel forming a reservoir (1) for storage of water or peracetic acid-containing solution. The reservoir (1) has a lid (4) which may be clipped onto the upwardly opening mouth of the reservoir. The lid (4) includes a pivotally mounted enclosure (14) which may close an opening in the lid (4) in the closed position or may be opened to allow removal of one or more wipes from a roll of sequential wipes (3).

A cylindrical tubular receptable (9) mounted on a support on the base the vessel (1) has an upper cap (5) which may be removed to allow insertion of a stack of cylindrical dosage forms (6). Apertures (7), (8) adjacent the lower end of the receptacle (9) communicate between the interior of the receptacle and the interior of the vessel (1). When the cap (5) is closed, the receptacle (9) is sealed so that air or water may only pass through the apertures (7), (8) in use. A permeable pad or plate (2) serves as a filter preventing solid particles caused by breakdown of the dosage forms (6) to be retained in the lower part of the vessel (1) so that they are not trained in the wipes (3) when the roll of wipes rotates as individual wipes are drawn through the aperture (14). The water or solution surface (10) is arranged in use to be between minimum (12) and maximum (13) levels indicated on indicia (11) integral with or mounted on the wall of the vessel. In use, the water level may only rise to an extent in the receptacle so that the lowermost one or two tablets (6) are contacted by the water and therefore only these lowermost tablets are able to dissolve. When these tablets have dissolved, the weight of the stack (6) causes the stack to descend so that the next lowermost tablets contact the water or solution formed from dissolution of the tablets.

In use, a predetermined quantity of tablets may be dissolved in the water in the reservoir (1) before the receptacle (9) and roll of wipes (3) are placed in the receptacle. In use of the apparatus, the receptacle (9) is charged with a stack of tablets (6) and the cap (5) is closed. The receptacle is then engaged making a support (not shown) which extends upwardly from the base or side wall of the vessel (1). Water is poured into the receptacle formed by the vessel (1) until the level (10) is between the minimum (12) and maximum (13) predetermined levels shown by the indicia (11). When the apertures (7), (8) of the reservoir (9) is located beneath the water level (10), passage of water into the receptacle (9) is restricted by air pressure within the receptacle.

The lowermost tablet (11) substantially blocks the cylindrical receptacle (7) so that water passing from the reservoir through the apertures (9) may only contact the lowermost tablet (11) until the tablet (11) disintegrates and dissolves. When the tablet (11) has dissolved, the remaining tablets (10) slide downwardly within the receptacle so that the next tablet (12) in the stack can contact the water supply.

The receptacle (7) may be composed of transparent polymeric material, to enable a user to monitor the supply of peracetic acid-generating tablets.

In an exemplary embodiment, the lower end of the receptacle may be located about 25mm from the base of the reservoir. Markings may be applied to the side of the reservoir (1) to provide maximum and minimum water levels, for example, at a height of 40mm and 60mm from the base of the reservoir respectively.

Figure 2 shows peracetic acid solution-generating apparatus similar to Figure 1 with the filter (2) supported in spaced relation to the base by supporting members (17). The apertures (7), (8) are located in the cavity (16) between the filter (2) and base of the vessel (1).

Figure 3 shows apparatus similar to Figure 1 with a pressure release valve or aperture (15) provided in the wall of the receptacle.

Figure 4 shows apparatus comprising a cylindrical tubular receptacle (20) having a cover (21), an openable lid (22) through which wipes may be successively drawn. A receptacle (23) mounted on a lower surface of the lid (21) and extends downwardly into the reservoir (20). A stack of tablets (24) is located in the receptacle. An array of apertures (25) allow water to pass from the reservoir into the receptacle and peracetic acid solution to pass from the receptacle into the reservoir. A cartridge (26) placed at the bottom of the reservoir (20) contains a quantity of the dosage form sufficient to generate a predetermined initial concentration of peracetic acid in the water (not shown) placed in the reservoir. The cartridge may be provided with apertures or may be composed of porous permeable material.

Figure 5 shows a further embodiment in which a support (30), for example, having a cylindrical configuration is mounted on the lower surface of the lid (31). A circular aperture in the lid (31) may be closed by a cover (34). When the cover is opened, a receptacle may be inserted through the lid into the support so that the lower end of the receptacle is in contact with water or peracetic acid solution contained in the reservoir (35). An opening (33) at the lower end of the support (30) submits passage of water and peracetic acid solution into and out of the receptacle (32).

Figure 6 shows removal of the receptacle through the aperture in the lid (21).

Figure 7 shows insertion of a fresh supply of dosage forms (36) through the aperture in the lid in a receptacle (37) inserted downwardly through the aperture in the lid (38). The cover (39) is open to permit insertion of the receptacle and dosage forms.

Figure 8 shows a receptacle when dosage forms are fully inserted, and the cover (34) is closed to secure the dosage forms in place.

In Figure 9, an embodiment similar to that shown in Figure 6 is provided with a body of absorbent material (36) placed on the bottom of the reservoir (37) to absorb any solid particles deposited from the solution following dissolution of the dosage forms in either the receptacle (38) or cartridge (39).