Introduction

There are several biocidal wipes which are commercially available. Such wipes contain various active agents such as peracetic acid, alcohol, quaternary ammonium compounds, and chlorine- based compounds such as bleach.

There are a number of problems with conventional wipes. Wipes containing alcohol or quaternary ammonium compounds have a narrow spectrum of activity. They are also not sporicidal and therefore have limited efficacy against important human pathogens such Clostridium difficile.

Liquid hydrogen peroxide is unstable and decomposes quickly. In addition, the stability of this biocide is greatly affected by temperature. Hydrogen peroxide is also highly corrosive and produces oxygen as a by-product; which corrodes iron containing metals.

Peracetic acid (PAA) is generated in situ when tetraacetylethylenediamine (TAED) is in the presence of an alkaline hydrogen peroxide solution. PAA solutions and wipes provide a very unpleasant odour. In addition, several safety concerns have been raised against PAA. The US National Institute for Occupational Safety and Health (NIOSH) have identified PAA as a primary irritant, known tumorigen and mutagen.

Bleach solutions are highly corrosive and have poor residual killing powder.

W089/05093A describes a wipe comprising a lofted non-woven substrate having solid particles of a chlorine release agent such as sodium dichloroisocyanurate (NaDCC) entrapped within its structure. The chlorine release agent is activated when dampened with water.

W090/02166A describes a system in which NaDCC particles are retained in an adhesive polymer which is used to bond layers of a substrate/wipe.

GB2439059A describes a wipe package comprising a first compartment containing a dry wipe impregnated with a dichloroisocyanurate and a second compartment containing an activating liquid that is released when a barrier between the compartments is ruptured. US5,814,159 describes a cleaning kit comprising a stack of wipes packaged with a container of cleaning fluid. The wipes are exposed to the chemicals in the cleaning fluid just before use - when the cleaning fluid is released from the container.

One problem with conventional systems in that whilst chlorine distribution throughout the wipes may initially be relatively uniform, over time the distribution of chlorine is unequal leading to a wide variation in the amount of available chlorine from one wipe to another and therefore variation in effectiveness.

This invention is directed towards providing a system which will overcome this problem.

Statements of Invention

The invention provides wipes with a dry disinfectant composition comprising NaDCC as a disinfectant agent, an effervescent base, and a surfactant.

An advantage of using NaDCC is that NaDCC releases approximately 50% of the chlorine as free available chlorine. The remaining 50% is maintained in a reservoir of stabilized chlorinated isocyanurates (Bloomfield and Miles, 1979). Depletion of free available chlorine causes an equilibrium shift and liberation of free available chlorine. The reservoir effect ensures that the chlorine is maintained in a stable form until a microbial challenge is present. In comparison, a hypochlorite solution (liquid bleach) immediately releases all its chlorine as free available chlorine. Therefore, the shelf life and chlorine residual of hypocchlorite products is inferior to that provided by NaDCC.

An advantage of using NaDCC in an effervescent base is that hypochlorous acid dissociates in water to form the hypochlorite (CIO-) anion. Chlorine becomes less effective with increasing pH (Hurst, 2001). The disinfection powder used in the invention includes an effervescent base that we believe increases the acidity of solutions. As a result, hypochlorous acid generated from the NaDCC is predominantly in the undissociated state (HOC1). In contrast, hypochlorite solutions are alkaline, which increases pH and reduces the effectiveness of the chlorine solution (Macedo and Barra, 2002). Therefore, the effervescent base increases the efficacy of the hypochlorous acid solution. In addition to improved efficacy, the effervescent system allows the quick dissolution of the disinfectant powder and facilitates the quick distribution of NaDCC into the wipe substrate.

Biofilms are a major problem in the hospital, agriculture, water and food processing sectors. They have been associated with the spread of hospital acquired infections (HAI’s). Moreover, they have been linked with the persistence and spread of multi drug resistant organisms (MDRO’s).

The formulation used in the invention contains a surfactant. The surfactant assists in penetrating, breaking-up and dispersing biofilms. This facilitates the removal of biofilm and reduces the persistence of pathogenic bacteria.

The presence of bioburden and organic material will inactivate biocides. Therefore, a cleaning step always precedes a disinfection step. This is the case in the hospital, agriculture, water and food processing sectors. The cleaning step requires a detergent product. The formulation of the invention contains a surfactant and the formulation acts both as a cleaner and a disinfectant. Therefore, a user only requires one product to achieve both applications. This ultimately saves the user both time and money.

The surfactant may be an anionic surfactant such as sodium dodecylbenzene sulphonate. The surfactant may comprise from 1% to 13% by weight of the disinfectant composition. The surfactant may comprise 2% to 12%, in one case about 2% by weight of the disinfectant composition.

A reduced level of surfactant improves dissolution time and reduces the amount of foam formed during activation without negatively impacting biofilm efficacy.

Biofilm, organic matter, fats and dirt are often attached to surfaces via strong intermolecular forces. Disinfectant wipes help remove such material via mechanical action. However, mechanical action alone is not enough and requires chemical intervention to help dissolve and break-up microbial structure such as biofilm. The surfactant is optimised to maximise both wipe mechanical action and detergency and therefore biofilm and microbial efficacy. In one case the disinfectant agent is a chlorinating agent. It is particularly preferred that the chlorinating agent is sodium dichloroisocyanurate. The disinfectant agent may be present in an amount of from 40% to 60% by weight of the composition. The disinfectant agent may be present in an amount of about 50% by weight of the composition.

In one case the effervescent base comprises an aliphatic carboxylic acid or an acid salt thereof and an alkali metal bicarbonate. The aliphatic carboxylic acid may be adipic acid. The aliphatic carboxylic acid may comprise from 20% to 30% by weight of the disinfectant composition. The aliphatic carboxylic acid may comprise about 23% by weight of the disinfectant composition.

The alkali metal bicarbonate may be sodium bicarbonate. The alkali metal bicarbonate may comprise from 10% to 30% by weight of the disinfectant composition. The alkali metal bicarbonate may comprise about 21% by weight of the disinfectant composition. The disinfectant composition may comprise an alkali metal carbonate. The alkali metal carbonate may comprise sodium carbonate. The alkali metal carbonate may comprise from 2% to 8% by weight of the disinfectant composition. The alkali metal carbonate may comprise about 3.9% by weight of the disinfectant composition.

Sodium carbonate and bicarbonate reduce water hardness (chiefly by removing calcium and magnesium ions). Hypochlorous acid is inactivated by excess hardness, consequently, the in solution stability is reduced. We believe that the effervescent base enhances in-solution stability by reducing water hardness.

The invention also provides a disinfectant system comprising a plurality of wipes having a dry disinfectant composition dispersed in or on each wipe, and an outer housing containing the wipes, the housing having a dispensing opening for withdrawing a wipe from the housing.

In one embodiment the wipe comprises a plurality of layers including a top layer, a bottom layer and at least one intermediate layer and wherein the dry disinfectant powder is dispersed over only the intermediate layer(s).

In one case the wipe comprises a number of sections which are folded over to form the layers. The wipe may comprise four quadrants which are folded to form the top, bottom and intermediate layers. The dry disinfectant powder may be applied to only one of the quadrants. In one embodiment the plurality of wipes are arranged in a stack of individual wipes.

Additional dry disinfectant powder may be applied to a top and/or a bottom of the stack.

The invention also provides a disinfectant system comprising:- i. a plurality of wipes having a dry disinfectant composition dispersed in or on each wipe; ii. a container for liquid, the liquid being releasable from the container to activate the disinfectant composition; and

iii. an outer housing containing the wipes and the liquid container, the housing having a dispensing opening for withdrawing a wipe from the housing.

In one embodiment the wipe comprises a plurality of layers including a top layer, a bottom layer and at least one intermediate layer and wherein the dry disinfectant powder is dispersed over only the intermediate layer(s).

In one case the wipe comprises a number of sections which are folded over to form the layers. The wipe may comprise four quadrants which are folded to form the top, bottom and intermediate layers. The dry disinfectant powder may be applied to only one of the quadrants.

In one embodiment the plurality of wipes are arranged in a stack of individual wipes.

Additional dry disinfectant powder may be applied to a top and/or a bottom of the stack.

The additional dry disinfectant composition applied to the top and/or bottom of the stack of wipes ensures a more even distribution of chlorine in the system.

Preferably the disinfectant agent is a chlorinating agent. For the reasons outlined above it is particularly preferred that the chlorinating agent is sodium dichloroisocyanurate. Particularly in the case of individually folded wipes in which the disinfectant agent is in an intermediate layer, distribution of the chlorinating agent, when activated, may be enhanced. Such alternative chlorinating agents include NaDCC dihydrate and Tricholoroisocyanuric acid (TCCA).

Anhydrous NaDCC has more available chlorine (approx. 62.0%) for disinfection than dihydrate NaDCC (approx. 56.0%). As a result, in comparison with the dihydrate form; a lower mass of anhydrous is required to achieve the same biocidal efficacy. This reduces overall cost. In addition, anhydrous NaDCC is more soluble than the dihydrate form. Therefore, it will have a quicker dissolution and substrate absorption rate. Although dihydrate NaDCC can be used as a chlorine donor, it is not the preferred option.

TCCA (Trichloroisocyanuric acid) is a chlorine donor. Like NaDCC, it forms the active biocide hypochlorous acid once dissolved in water. Unlike NaDCC, TCCA is only slightly soluble in water. Therefore, it slowly dissolves in water. The quick and full dissolution of biocide is crucial to allow full absorption of disinfectant into the wipe substrate. Therefore, TCCA formulations would be less effective at achieving full absorption and equal distribution of chlorine in the system. In addition, once dissolved in water, TCCA produces a strong and unpleasant odour. Although TCCA can be used as an alternative biocide, it is not preferred.

In one case the housing is adapted to orientate the dispensing opening in a substantially vertical plane. The housing may comprise a base support.

In some cases the wipes comprise non-woven polymeric fibres such as polypropylene fibres.

In one case the liquid is water.

The system may further comprise a holder for the housing, the holder being adapted to orientate the wipes substantially vertically.

The invention also provides a method for activating a disinfectant system of the invention comprising the steps of:- rupturing a container to release the liquid;

turning the housing containing the wipes to wet the wipes and activate the disinfectant composition; and

orientating the housing so that the wipes are substantially upright for dispensing.

The dry disinfectant formulation may be in a powder firm with an average grain size of from 1 to 1200 pm. The invention will be more clearly understood from the following description thereof, given by way of example only, in which

Figs. 1 to 3 are a series of drawings illustrating the folding of a wipe;

Figs. 4 to 6 are a series of drawings illustrating the folding of another wipe;

Fig. 7 is an illustration of a repeating unit of the folded wipes of Figs. 3 and 6;

Fig. 8 is a drawing of a stack of wipes formed from the folded wipes of Figs. 3 and 6;

Fig. 9 illustrates a disinfectant system comprising a plurality of wipes, a container for liquid and an outer housing for the wipes and the container;

Fig. 10 is an illustration of the outer housing;

Figs. 11 to 14 are a series of drawings illustrating activation of the wipes;

Fig. 15 illustrates a stand and a package of wipes;

Fig. 16 is a chart of chlorine distribution through a package of wipes;

Figs. 17 and 18 illustrate deposition of a dry disinfectant composition on a wipe;

Fig. 19 illustrates a stack of wipes with a container for liquid;

Fig. 20 illustrates an outer housing for the stack of wipes and container of Fig. 19;

Figs. 21 and 22 are cross sectional views of a stack of wipes, a container for liquid and an outer housing;

Fig. 23 and 24 illustrate deposition of a dry disinfectant composition on a wipe; Fig. 25 illustrates a stack of wipes;

Fig. 26 illustrates an outer housing for the stack of wipes; and

Figs. 27 and 28 are cross sectional views of a stack of wipes and an outer housing.

Detailed Description

Example 1

A dry formulation comprising a disinfecting agent, a surfactant and an effervescent base is prepared from the following (% by weight):

Sodium dichloroisocyanurate: 50.00%

Adipic acid: 23.34%

Sodium bicarbonate: 20.79%

Sodium carbonate: 3.87%

Sodium dodecylbenzene sulphonate: 2.00%

Sodium dichloroisocyanurate is a disinfectant agent.

Sodium dodecylbenzene sulphonate is a surfactant.

Sodium bicarbonate and sodium carbonate are the source of carbon dioxide in the effervescent formula.

Adipic acid is a key component of the acid-base effervescent reaction. Once in contact with moisture, the adipic acid reacts with the carbonate salts to produce carbon dioxide gas.

The formulation is in a powder form with an average grain size of from 1 - 1200 pm.

The formulation is dry mixed and remains stable for 2 years when stored at 5-40°C/65% relative humidity. Stability is also maintained at relative humidity levels of 75%.

Example 2 - Wipe The primary substrate is preferably polypropylene (100%) non-woven lint-free wipes. Lint may assist in transfer of infection. Propylene wipes have good absorption and mechanical properties and facilitate release of biocide to the surface of the wipe. Polyethylene non-woven lint-free wipes also provide similar advantages.

Other substrates may also be used such as 30, 50 or 70% polyethylene or polypropylene. A biodegradable substrate such as viscose (30, 50, 70 and 100%), rayon (30, 50, 70 and 100%) and cellulose (30, 50, 70 and 100%) may also be used.

Various blends may also be used as substrates such as viscose (50%)/polyester (50%), viscose (20%)/polyethylene (35%) and polypropylene (85%)/viscose (15%).

The wipes preferably are 25 to lOOgsm.

One example is a 26gsm polypropylene medium task wipe such as available from Quattro.

Referring to Fig. 1, to ensure even distribution of the disinfectant powder to a dry wipe 1, the wipe 1 is divided into a number of sections, in this case four quadrants A, B, C, D.

The wipe 1 is folded as illustrated so that quadrant C and D are folded over A and B respectively. The disinfection powder (for example an amount of about 0.3g) is applied to quadrant D (which lies on top of B) in this example as illustrated in Fig. 2. The wipe is then folded as illustrated so that quadrant C is folded over D so that the wipe has four quadrants on top of one another with the quadrant D to which the disinfection composition has been applied on the second layer from the bottom as shown in Fig. 3.

Referring to Fig. 4, to ensure even distribution of the disinfectant powder to a dry wipe 21, the wipe 21 is divided into a number of sections, in this case four quadrants A, B, C, D.

The wipe 21 is folded as illustrated so that quadrant C and D are folded over A and B respectively. The disinfection powder (for example an amount of about 0.3g) is applied to quadrant C (which lies on top of A) in this example as illustrated in Fig. 5. The wipe is then folded as illustrated so that quadrant D is folded over C so that the wipe has four quadrants on top of one another with the quadrant C to which the disinfection composition has been applied on the second layer from the bottom as illustrated in Fig. 6.

Referring to Fig. 7, to ensure even distribution of free chlorine, the wipe pack consists of 7 horizontally stacked repeating units. A repeating unit consists of wipe 1 on the bottom layer and wipe 21 on the top layer. A single wipe 1, is stacked horizontally on top of the repeating units. The final wipe pack as illustrated in Fig. 8 consists of 15 wipes.

Example 4 - Cracking Bag

A suitable cracking bag 2 is a low-density polypropylene/polyethylene bag is filled with an activating liquid which in this case is water. For example, the cracking bag may contain 210ml deionised ¾0 for activating a plurality of wipes containing 4.5g in total of disinfecting powder.

Example 5 - Outer Housing

A suitable outer housing is of a flexible material such as low-density polypropylene/polyethylene outer housing 3 having an outlet opening 4 which may be covered by removable flap or lid.

Example 6 - Assembly

Referring to Fig. 9, a plurality of wipes 1 prepared as outlined above are stacked to form a wipe stack 10 which may contain 15 wipes, by way of example. The housing 3 contains the cracking bag 2. An additional amount of disinfectant powder 11 (such as 0.3g) is placed on top of the cracking bag 2. The wipe stack 10 may be placed in the housing 3 on top of the cracking bag 2 as illustrated in Fig. 9. A further additional amount of disinfectant powder 12 (such as 0.3g) may be placed on top of the wipe stack 10. The housing 3 is then sealed. The housing 3 is also shown in Fig. 10.

Example 7 - Activation

To activate the wipes for use hand pressure (Fig. 11) is first applied to the outer housing sufficient to cause the cracking bag 2 to burst and release water. The housing is then manually rotated (Fig. 12) about its horizontal and vertical axis for approximately 10 seconds. This is the initial priming phase. To activate the dissolution of the disinfectant powder and ensure an even chlorine distribution, the unit is placed horizontally with face Xi in contact with a flat surface (Fig. 13). The unit is kept in this orientation for a period such as 3 minutes. Following this standing period, the unit is rotated and placed horizontally with face X2 in contact with the flat surface (Fig. 14). The unit is kept in this orientation for a further period such as 3 minutes. Following this standing step, each wipe is saturated with deionised water and full dissolution of powder has occurred. Once dissolved, the NaDCC is immediately activated by the deionised water. The activated NaDCC forms the powerful biocide hypochlorous acid, which is distributed equally in every wipe. Once activated, the housing system is stored vertically such that the outlet 4 for the wipes is located in a vertical plane.

The housing containing the activated wipes is then placed in a suitable standing rack 20 which retains the housing in the desired vertical orientation as illustrated in Fig. 15.

Example 8 - Test

Chlorine Distribution in Wipe Pack

(1) The disinfectant system was set up and activated as outlined above.

In this case the formulation was:

NaDCC 41.45%

Adipic Acid 20.16%

Sodium Bicarbonate 21.06%

Sodium carbonate 4.64%

Sodium dodecylbenzene sulphonate 12.70%

(2) Following activation, a wipe was removed from the system. Liquid was extracted from the wipe via manual squeezing. The extracted liquid was collected in a beaker and then transferred to a labelled plastic container. Using a glass pipette, a 5 ml sample was transferred to a conical flask. Then, 45 ml of deionised water, 10 ml of potassium iodide (10% (w/v)) and 5 ml of acetic acid (17.5 M) was added to the conical flask. Using 0.1 M sodium thiosulfate and a starch indicator, the concentration of free available chlorine was determined using an iodometric titration.

(3) Step 2 was repeated for each wipe, and the free chlorine distribution within the disinfectant system was examined.

(4) Steps 1 - 3 were repeated to examine the chlorine distribution and residual chlorine concentration of the system following 72 hours storage in the vertical plane.

Table 1: Free chlorine distribution through wipe pack The results are plotted in Fig. 16.

Following activation, it was found that the disinfection powder in each wipe had fully dissolved. It took approximately 3-6 minutes for full dissolution of the powder. The effervescent (adipic acid, sodium bicarbonate, sodium carbonate) component facilitated the fast dissolution of the powder.

It was found that each wipe in the disinfection system had levels of free chlorine between 5382 - 8074 ppm. As shown in Table 1, the average free chlorine concentration within the system is 6758 ppm (Standard deviation (SD): 784.01, coefficient of variation (CV): 11.60%. The target free chlorine concentration for each wipe is 6910 ppm. No wipe had a % difference (see Eqn 1.1) from the mean greater than 20.5%. Moreover, the free chlorine concentration was maintained in each wipe for a period up to 72 hours. The target free chlorine concentration in each wipe is 6910 ppm. The % difference of the average from the target was less than 2.25% (see Eqn 1.2). To achieve a Clostridium difficile spore kill in 4 minutes using NaDCC (US EPA SOP MB-31), a minimum free chlorine concentration of 4306 ppm must be maintained in each wipe. Using a target concentration of 5572 ppm, the system will always deliver a minimum and maximum free chlorine concentration of 4435 and 6659 ppm respectively. Moreover, the chlorine in each wipe will be maintained within this range for a period up to 72 hours. In addition, each wipe will be able to kill Pseudomonas aeruginosa and Staphylococcus aureus biofilm 4 minutes post application.

Eqn LI: % Difference from the mean = ((Xi - X ₂ )/X ₂ )*100

: wipe free chlorine concentration

X ₂ : average free chlorine concentration

Eqn 1.2: % Difference of the mean from the target = ((Yi - X2)/Yi)* 100

Y _! : target free chlorine concentration

X ₂ : average free chlorine concentration

Alternative Systems

Referring to Figs. 17 to 22, there is illustrated another disinfectant system comprising a plurality of wipes with a dry disinfectant powder as described above deposited on the wipes. A typical dose is 0.15g. In this case the wipes 30 are not folded and the disinfectant powder 31 is deposited in the centre of the wipe as illustrated in figs, 17 and 18. Typically the wipe is 23.5cm x 13cm and the disinfectant is deposited in a central area which may be 5cm x 1cm.

The wipes are then stacked one upon the other as illustrated in Fig. 19. An additional dose 35, 36 of the disinfectant composition is deposited in this case below 35 and above 36 the stack of wipes. These reservoir/booster doses 35 and/or 36 of disinfectant composition ensure that the desired free chlorine concentration is maintained throughout the pack of wipes when the system has been activated.

A cracking bag 40 containing water (preferably deionised water) is placed on top of the stack of wipes and the stack of wipes and cracking bag 40 are placed in an outer housing/package as described above and illustrated in Figs. 21 and 22. The outer housing/package 45 has an opening 46 through which a wipe may be withdrawn, as required. The opening may be closed by a suitable flap or lid. Another disinfectant system is illustrated in Figs. 23 to 28. The system comprising a plurality of wipes 50 with a dry disinfectant powder 51 as described above deposited on the wipes. A typical dose is 0.15g. In this case the wipes 50 are not folded and the disinfectant powder 51 is deposited in the centre of the wipe as illustrated in Figs. 23 and 24. Typically the wipe is 23.5cm x 13cm and the disinfectant is deposited in a central area which may be 5cm x 1cm.

The wipes 50 are then stacked one upon the other as illustrated in Figs. 25 and 26. An additional dose 55, 56 of the disinfectant composition is deposited in this case below 55 and above 56 the stack of wipes (Fig. 26). These reservoir/booster doses 55 and/or 56 of disinfectant composition ensure that the desired free chlorine concentration is maintained throughout the pack of wipes when the system has been activated. The stack of wipes are placed in an outer housing/package 65 has an opening 66 through which a wipe may be withdrawn, as required. The opening may be closed by a suitable flap or lid.

A disinfectant system comprising a plurality of dry wipes was tested. Each wipe had a planar configuration and was layered with a single solid dose of disinfectant. The disinfectant composition comprised of sodium dichloroisocyanurate (50%), adipic acid (23.34%), sodium bicarbonate (20.79%), sodium carbonate (3.87%) and sodium dodecylbenzene sulphonate (2%).

A stack of wipes was created whereby one single planar wipe was layered on top of another as illustrated in Figs. 23 to 28.

Prior to stacking, a single dose of disinfectant (0.15 g) was added to the centre of each wipe as illustrated in Figs. 23 and 24. Then a stack of wipes was created whereby one single planar wipe (containing dose) was layered on top of the other as illustrated in Fig. 25. The disinfectant system was housed in an outer polypropylene packaging 65. The top layer of the outer packaging contained a resealable opening 66. A single dose (0.15 g) 55 of disinfectant was applied to the bottom layer of the packaging. It was located on the centre of the bottom layer. In addition, a second dose (0.15g) 56 was centrally located on the wipe at the top of the stack as illustrated in Fig. 26.

The system was validated by measuring the free chlorine concentration in each wipe after activation. Following activation, each wipe delivered a biocidal solution with a minimum of 4306 ppm free chlorine. Each wipe is capable of delivering the appropriate strength of biocide for up to 72 hours. This can be extended up to 7 days when using deionised water.

It was found that following activation, each wipe delivers a biocidal solution with a minimum of 4306 ppm free chlorine. The disinfectant composition kills Clostridium difficile in four minutes.

The disinfectant system was activated using the following mechanism:

The seal was removed from the opening 66. Then 157 ml of tap water was manually added to the device via the opening 66. The seal was then placed back on the opening 66. The system was then activated by rotating the bag along its vertical and horizontal axis for 10 seconds (Fig 12). Following this, the system was placed horizontally with face XI on a flat surface for 3 minutes (Fig. 13). After the system was place on the opposite side (face X2) for a further 3 minutes (Fig. 14). The activation phase allowed complete dissolution of the dose and the equal distribution of the biocide throughout the wipe pack.

Following activation, the system was placed in a container in a vertical position as illustrated in Fig. 15. The vertical storage position ensured that an equal distribution of free chlorine was maintained throughout the wipe pack.

A set of five systems was activated simultaneously. At time zero, a single pack was removed and the distribution of free chlorine within the system was examined. This involved the manual extraction of liquid from each wipe. Then the free chlorine concentration of the biocidal solution was determined via iodometric titration. This was repeated for 1, 2, 3, 5 and 7 days.

At day zero, it was found that following activation an equal distribution of free chlorine was maintained in the system. Each wipe within the system was able to maintain a free chlorine concentration of from 4306 to 6500 ppm. Moreover, each wipe was able to maintain a concentration of greater than 4306 ppm free chlorine. It was found that activated systems maintained an equal free chlorine distribution up to 3 days when using tap water and 7 days when using deionised water.

In the invention, each wipe is loaded with a predefined amount of disinfectant powder. In addition, disinfectant powder is placed below and on top of the wipe stack. The amount of powder is based on the saturation level of the wipe substrate (i.e. the amount of liquid a wipe can absorb). The unique loading pattern ensures that each wipe is fully saturated with deionised water. In addition, the loading pattern ensures full powder dissolution and that each wipe absorbs an equal amount of free chlorine during activation.

The dry powder within the disinfectant system is kept in an inert state. While in the inert state, the disinfectant powder has a shelf life of at least 24 months. The cracking bag activation system allows the disinfectant powder to stay in an inert state until required for use. Once activated, the disinfectant powder is dissolved in deionised ¾0 and NaDCC is converted to the active biocide hypochlorous acid and the biodegradable by-product cyanuric acid. Maintenance of the disinfectant powder in the dry inert state, allows the system to have a far superior shelf life to that of liquid chlorine products such as sodium hypochlorite.

The activation mechanism involves repeated inversions of the system to ensure each wipe is saturated with deionised H ₂ 0. This step allows the quick and full dissolution of the disinfectant powder and rapid uptake into each wipe. The full dissolution and rapid uptake ensure that each wipe contains an equal concentration of the disinfectant solution. The inversion times and distribution of disinfectant powder within the system have been optimized to ensure full dissolution and an equal distribution of chlorine.

Chlorine based wipe systems are known to form concentration gradients, thereby becoming ineffective disinfectant systems. The disinfection system of the invention and its activation method prevent a chlorine concentration gradient from occurring. Therefore, each wipe within the system contains the necessary biocidal concentration to effectively disinfectant surfaces.

The rack maintains the system in a vertical plane and prevents the formation of a chlorine concentration gradient occurring during storage.

The invention is not limited to the embodiments hereinbefore described, which may be varied in construction and detail. References

Bloomfield, S.F., Miles, G.A., 1979. The antibacterial properties of sodium dichloroisocyanurate and sodium hypochlorite formulations. J. Appl. Bacteriol. 46, 65-73.

Hurst, C.J., 2001. Disinfection of water: drinking water, recreational water and wastewater. In: Block, S.S. (Ed.), Disinfection, Sterilization and Preservation, 5th ed. Lippincott Williams & Wilkins, Philadelphia, PA, USA, pp. 1023-1047. Macedo, J.A.B., Barra, M.M., 2002. Derivados dorados de origem organica uma solucao para o porcesso de desinfeccao de agua potavel e para desinfeccao de industrias. In: VI Simposio Italo Brasileiro de Engenharia Sanitaria e Ambiental, September 1-5, 2000.