WO2024062242A1

WO2024062242A1 - Verification composition

Info

Publication number: WO2024062242A1
Application number: PCT/GB2023/052436
Authority: WO
Inventors: Madison PEPPLER
Original assignee: Tristel Plc
Priority date: 2022-09-20
Filing date: 2023-09-20
Publication date: 2024-03-28
Also published as: GB202213756D0; GB2622594A

Abstract

A verification composition for application to a surface to be decontaminated is disclosed. The composition is a manually-spreadable solid at room temperature, and comprises up to 50 wt% of one or more waxes, up to 25 wt% of one or more oils, up to 30 wt% of a solvent, up to 15 wt% of one or more emulsifiers, and up to 10 wt% of a dyestuff. A method of verifying a decontamination procedure comprising applying the decontaminating composition to a surface using an applicator is also disclosed.

Description

VERIFICATION COMPOSITION

FIELD

This disclosure relates to a verification composition for application to a surface to be decontaminated, in particular, but not exclusively, for verifying that a substance has been applied to, or removed from, the whole of a desired area of a surface.

BACKGROUND

Within the healthcare market, decontamination procedures are widely used for disinfection and cleaning. Areas of particular importance include the reprocessing of non-lumened medical devices and environmental surface disinfection. For infection control and patient safety, it is essential that any process used for decontamination or disinfection is effective in practice, taking into account the products used for disinfection, the training and performance of the user, environmental factors, and so on. Accordingly, it is desirable to provide methods for verifying that a decontamination procedure has been performed correctly and effectively.

Unlike many other oxidising disinfectants, chlorine dioxide is typically generated at point of use by combining sodium chlorite or chlorate with an acidifier. This allows a long product shelf life without the hazards associated with shipping high strength oxidising solutions. Reprocessing of non-lumened medical devices using chlorine dioxide disinfectants may be conducted manually by the user via the application of disinfectant to the surface using a spreading medium (including but not limited to wipes, sponges, gloves). This manual approach has multiple advantages compared to automated processes, such as:

• lower capital investment;

• reduced space requirements;

• flexibility of location of use;

• elimination of service and maintenance provision.

Automated processes are also not practical for the disinfection of other surfaces, such as floors, walls, work surfaces and so on. A drawback of manual decontamination processes is that effective disinfection relies exclusively on the user adhering to not only the user instructions but also ensuring that all parts of the surface to be treated are adequately covered in disinfectant with enough to ensure that the drying time is longer than the contact time.

Against that background, it would be desirable to provide means for verifying that the application of a substance to a surface in a decontamination procedure has been performed correctly.

SUMMARY OF THE INVENTION

Aspects of the invention are specified in the independent claims. Preferred features are specified in the dependent claims.

Disclosed herein is a verification composition for application to a surface to be decontaminated. The composition is a manually-spreadable solid at room temperature, and comprises:

- up to 50 wt% of one or more waxes;

- up to 25 wt% of one or more oils;

- up to 30 wt% of a solvent;

- up to 15 wt% of one or more emulsifiers; and

- up to 10 wt% of a dyestuff.

The verification composition, by virtue of its constituents, is a waxy, mouldable, solid material at room temperature (i.e. 25°C) that exhibits shear-thinning behaviour. In this way, the verification composition can be applied to and spread over a surface, such as a medical device, using a gloved finger or an applicator device to achieve a uniform, even coating of the verification composition on the surface. Once applied, the verification composition remains adhered to the surface and does not run or drip.

The verification composition preferably remains in a mouldable solid form in a temperature range of between 10°C and 40°C, and more preferably in a temperature range of between 15°C and 35°C. The verification composition, when applied to the surface, allows a user to visually identify the presence of the verification composition. After application, the verification composition can be removed from a surface using an applicator or procedure required in a decontamination process, and any remaining verification composition will show regions of the surface from which the verification composition has not been successfully removed. The verification composition can therefore act as a training aid and/or a compliance aid.

The dyestuff allows the verification composition to be readily seen after application to the surface. The dyestuff may undergo a colour change upon exposure to a decontaminating composition, such as a disinfectant. Preferably, the dyestuff undergoes a colour change in the presence of chlorine dioxide. In this case, when used with a chlorine dioxide disinfectant composition, the verification composition can additionally provide verification that chlorine dioxide is present. The dyestuff may for example comprise an anthocyanin, an anthocyanidin or a betanin dyestuff. In one embodiment, the dyestuff comprises black carrot extract. The composition may comprise up to 10% of the dyestuff.

The or each wax is preferably a non-petroleum based wax. The or each wax may have a dropping point of at approximately 50 to 60°C. The wax or at least one of the waxes may comprise a plant-derived wax. In an example, the wax or at least one of the waxes is selected from the group consisting of soya wax, palm wax, candelilla wax, carnauba wax, stearic acid and sunflower wax, and beeswax. In a preferred embodiment, the verification composition comprises a blend of beeswax and soya wax. The verification composition may comprise up to 40 wt% of the one or more waxes. The total wax content of the verification composition may be between 25% and 35% by weight.

The oil enhances spreadability of the verification composition, and may be selected from the group consisting of castor oil, olive oil, rapeseed oil, passionflower oil, sunflower oil, coconut oil and marula oil. The composition may include up to 25 wt%, preferably up to 20 wt%, of the solvent.

The solvent may comprise isododecane or isohexadecane.

The emulsifier or one of the emulsifiers may comprise a polyethylene glycol (PEG) or a fatty acid. For example, the composition may comprise PEG 100 and/or glycol stearate as an emulsifier.

The verification composition may comprise a preservative. For example, the verification composition may comprise up to 2% of the preservative.

In an embodiment, the verification composition comprises: between about 20 and about 40 wt%, preferably between 25 and 35 wt%, of wax in total, wherein the or each wax is preferably selected from the group consisting of soya wax, palm wax, candelilla wax, carnauba wax, stearic acid, sunflower wax, and beeswax; between about 15 and about 25 wt%, preferably between 20 and 25 wt%, of oil in total, wherein the or each oil is preferably selected from the group consisting of castor oil, olive oil, rapeseed oil, passionflower oil, sunflower oil, coconut oil, and marula oil; between about 5 and about 15 wt%, preferably between 9% and 13% of emulsifier in total, wherein the emulsifier is preferably selected from the group consisting of glycol stearate, PEG 100, and mixtures thereof; between about 5 and about 15 wt% of the dyestuff; between about 5 and about 15 wt% water; and between about 15 and about 25 wt% of the solvent, preferably between 18 and 22 wt%, wherein the solvent is preferably selected from the group consisting of isododecane, and isohexadecane.

In another embodiment, the wax is a blend of between about 10 and about 20 wt% soya wax and between about 10 and about 20 wt% beeswax, the oil is castor oil, the emulsifier is a mixture of glycol stearate and PEG 100, and the solvent is isododecane. In one embodiment, the verification composition comprises between about 10 and about 20 wt%, preferably about 13 wt%, soya wax; between about 10 and about 20 wt%, preferably about 14 wt% beeswax; between about 15 and about 25 wt%, preferably about 22 wt% castor oil; between about 5 and about 15 wt%, preferably 11 wt%, of a mixture of glycol stearate and PEG 100; between about 5 and about 15 wt%, preferably 9 wt% of a dyestuff, preferably an anthocyanin dyestuff; between about 5 and about 15 wt%, preferably about 11 wt% water; between about 15 and about 25 wt%, preferably about 19 wt% isododecane; and between 0 and about 2 wt%, preferably about 1 wt% parmetol bpx as a preservative.

Also disclosed is the use of a verification composition as described above for verifying the complete removal of the composition from a surface during decontamination.

Also disclosed is a method of verifying a decontamination procedure in which the decontamination procedure comprises applying a decontaminating composition to a surface using an applicator, the method comprising, before applying the decontaminating composition, applying to a whole area of the surface a verification composition as described above, applying the decontaminating composition to the surface using the applicator, such that application of the applicator to the surface removes the verification composition, and inspecting the surface to verify that all of the verification composition has been removed. When the decontaminating composition comprises chlorine dioxide and the dyestuff of the verification composition undergoes a colour change in the presence of chlorine dioxide, the method may further comprise, after applying the decontaminating composition to the surface, inspecting the applicator to verify that the colour change has occurred.

The verification composition can also be used as a visual indicator to identify that a surface is in a dirty or unknown state to avoid potential contamination events.

The verification composition is preferably in the form of a waxy, spreadable solid, and may be applied to a surface by any suitable means, including spreading using a gloved hand, or by a suitable applicator device.

The verification composition and associated methods are particularly suitable for use in healthcare settings where cleaning and/or disinfection is required. Areas of use may include medical surfaces (such as in a patient bed space area), invasive and non-invasive medical devices (including ultrasound probes, endoscopes, nasendoscopes and so on), flooring and walls, janitorial applications, and training and compliance aids.

Throughout this specification, the amount of a component in a composition, expressed as a percentage, is a reference to the percentage by weight (i.e. weight/weight, wt% or wt/wt).

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which like reference signs are used for like features, and in which:

Figure 1 is a flowchart showing steps in a prior art process for decontaminating a surface, for example of a medical device;

Figure 2 is a flowchart showing a method of verifying that a substance has been removed correctly from a surface; and

Figure 3 is a schematic illustration of the method of Figure 2 being performed.

DETAILED DESCRIPTION

Figure 1 describes a prior art decontamination procedure using a system of a type known for example from WO 2005/107823 A1 . Such a system comprises a plurality of pre-clean wipes contained within individual sachets, a two-part disinfecting wipes system, and a plurality of rinse wipes, again contained within individual sachets. The disinfecting wipes system comprises a dispenser containing a first reagent and a plurality of disinfecting wipes impregnated with a second reagent and contained within individual sachets, whereby a disinfecting composition can be prepared by dispensing the first reagent onto the disinfecting wipe to mix with the second reagent. The first and second reagents react to form a disinfecting composition. For example, chlorine dioxide can be generated using a first reagent comprising sodium chlorite or chlorate and a second reagent comprising an acidifier.

In a first step 101 , the pre-cleaning composition is prepared by removing a pre-clean wipe from its sachet. In a second step 102, the pre-cleaning composition is applied to the surface to be cleaned by wiping the surface with the pre-clean wipe. In this way, the pre-clean wipe can be used to remove major contaminants, such as fluids or particles, from the surface.

In a third step 103, the decontaminating composition is prepared, by first removing a disinfecting wipe from its sachet, and then dispensing a quantity of the second reagent onto the wipe from the dispenser (for example as a foam). The wipe is then folded and scrunched to mix the reagents and generate the liquid disinfecting composition in-situ in the wipe.

In a fourth step 104, the decontaminating composition is applied to the surface by wiping the surface with the activated disinfecting wipe, to coat the surface with the liquid decontaminating composition. Then, in a fifth step 105, the user waits for a prescribed contact time, to allow the decontamination composition to dwell on the surface for long enough to be effective in chemically disinfecting the surface.

In a sixth step 106, a rinsing composition is prepared by removing a rinse wipe from its sachet. In a seventh step 107, the rinsing composition is applied to the surface by wiping the surface with the rinse wipe. The rinse wipe is used to remove any residual decontaminating composition from the surface to prepare the surface for its next clinical use.

In the decontamination procedure of Figure 1 , effective disinfection or decontamination with the decontaminating composition, and effective use of the pre- clean and rinse wipes, rely upon several steps being correctly performed. For example, in the fourth step 104, it is important that the decontaminating composition is applied to the whole surface to be decontaminated, without leaving areas not wetted by the decontamination composition. One object of the present invention is to provide a verification method, and associated verification composition, for validating whether this requirement has been met by a user performing at least step 104 of the procedure of Figure 1 .

In one aspect, the present invention provides a composition, referred to as a verification composition, which when applied to a surface provides a visual indication of the extent to which the verification composition has covered the surface. The visual indication is provided by the presence of a dyestuff that renders the verification composition visible to the user.

In a verification process, the verification composition is used as an aid to check that a decontaminating composition (for example a pre-clean composition, disinfecting composition or rinse composition) that must be applied to the surface using an applicator (such as a wipe, mop sponge, gloved hand etc.) as part of a verification procedure has been applied to the whole area of a surface to be decontaminated.

In the verification process, shown in Figures 2 and 3, the verification composition 16 is first applied to all areas of the surface 10 to be decontaminated using a suitable applicator or by hand (step 301 in Figure 2). Figure 3(a) shows an example in which the verification composition 16 is provided in a lipstick-style tube container 17.

As is known in the art, in such a container 17, a movable carriage (not shown) holds a block or stick of the substance (in this case the verification composition 16) and is arranged to telescope with respect to a body 18 of the container 17. In this example, a ring 19 can be rotated with respect to the body 18 to drive the carriage linearly with respect to the body 18 (via a screw mechanism, not shown) to extend or retract the verification composition 16 out of or in to the body 18, although in other cases the carriage may be directly movable by the user (e.g. in a push-up type container). In the illustrated example, the verification composition 16 is extended from the container 17 and applied to the surface 10 by rubbing the verification composition 16 against the surface (Figure 3(b)). In other examples, the verification composition 16 could be spread on the surface 10 by a gloved finger after transfer from the container 17, or the verification composition 16 could be transferred from the container 17 to a gloved finger and applied to the surface 10 by the finger. In the latter case, the verification composition 16 could be provided in a different type of container, such as a tube, tub, can, bag, pouch and so on.

After application of the verification composition 16, the surface 10 is inspected to ensure that all of the desired areas are covered by the verification composition 16 (see Figure 3(c)). Then, the applicator 22 (e.g. a wipe) used to apply the decontaminating composition 24 to the surface 10 (step 302 in Figure 2) in the manner prescribed in the decontaminating procedure, optionally with the decontaminating composition 24 pre-applied to the applicator 22 as shown in Figures 3(c) and 3(d). The applicator 22 removes the verification composition 16 from the surface 10, as shown in Figure 3(e), and the verification composition 16 is transferred to the applicator 22. After use of the applicator 22, the surface 10 can be inspected (step 303 in Figure 2) to reveal any areas in which the verification composition 16 has not been removed, indicating that the applicator 22 did not sufficiently cover those areas. If no such missed areas are identified, the suitability of the prescribed applicator 22 and application method has been verified. If missed areas are identified, appropriate corrective action can be taken.

The dyestuff used in the verification composition may exhibit a colour change upon exposure to an active component in a decontaminating composition. For example, the dyestuff may be oxidised in the presence of a disinfectant, so that the dyestuff loses its colour. In such cases, when the verification composition is removed from a surface using a wipe that carries the decontaminating composition, as shown in Figure 3, the wipe 22 can be inspected subsequently (step 304 in Figure 2) to check that the verification composition that has been transferred to the wipe 22 has undergone the colour change (Figure 3(f)), verifying the presence of the decontaminating composition on the wipe. When used in the way described in Figures 2 and 3, the verification composition 16 can act as a compliance aid. The surface 10 is first fully covered with the verification composition 16 and then removed with the wipe 22 carrying the decontaminating composition 24. Compliance is achieved when all of the verification composition 16 has been removed, indicating that the wipe 22 has contacted all of the areas of the surface.

It will be appreciated that using the process described in Figures 2 and 3, the verification composition can be used as a training aid during training of users, to ensure that the technique employed by a user in covering a surface when using an applicator is sufficiently thorough to adequately contact all of the necessary areas of the surface.

A further use of the verification composition is as a visual indicator of non-clean status. The verification composition can be applied partly or wholly to a surface, such as a medical device, to provide a clear visual indicator that the device or other surface requires decontamination and/or other reprocessing before it can be used again. Used in this way, the verification composition can be helpful in reducing the risk of a device being left in an unverified state with regards to cleanliness and suitability of use, for example in a busy clinical setting with multiple users.

The verification composition may be provided in a single-use package, such as a pouch or sachet, in which a suitable quantity of the verification composition is contained to cover the surface to which the application relates, such as the surface of a medical device. In this way, the user is assisted in applying an appropriate quantity of the verification composition to the surface.

In its broadest form, the verification composition used in the above processes contains a combination of one or more waxes, one or more oils, and one or more dyestuffs. Preferably, the composition also includes one or more solvents and one or more emulsifiers. The verification composition also preferably includes a preservative. The wax component may include one or more waxes and preferably comprises up to 50% of the composition by weight. The or each wax is a mouldable solid at room temperature. The wax component provides the bulk texture and structure of the composition and provides the composition with the shear-thinning, malleable characteristics associated with the spreadability of the composition. A blend of waxes may be used to provide optimum spreadability and structure. Preferably, the or each wax is a non-petroleum derived wax. For example, plant-derived waxes such as soya wax, candelilla wax, carnauba wax, stearic acid or sunflower wax may be used. Beeswax is also suitable. The waxes are preferably cosmetic grade, and may have a dropping point of around 50°C to 60°C (measured in accordance with ASTM D3954).

In one embodiment, the composition comprises approximately 13 wt% soya wax and 14 wt% beeswax, by weight. Soya wax is non-petroleum derived, renewable and biodegradable. Beeswax is harder than soya wax and also acts as an emulsifier, helping to produce a composition with a suitable hardness and homogeneity. An approximately equal amount of beeswax and soya wax has been found to provide a suitable consistency and spreadability.

The oil component enhances the spreadability of the composition. It has been determined that the composition may include up to 25 wt% of the oil component without adversely affecting the drying behaviour and greasiness of the composition. Preferably, the oil is a vegetable or other naturally-derived oil. One particularly suitable oil is castor oil, which has a suitable consistency, is readily accessible and biodegradable.

The solvent component enhances drying of the verification composition on the surface after application. The solvent is preferably one or a combination of primary alcohols, secondary alcohols, straight chain alkanes and branched chain alkanes. Preferably, the solvent comprises straight chain and/or branched chain alkanes. More preferably, the solvent is isododecane or isohexadecane. The composition preferably comprises up to 30 wt%, more preferably up to 25 wt%, and most preferably up to 20 wt% of the solvent.

The emulsifier component acts as a thickener and emulsifier, and helps the composition to adopt the colouring from the dyestuff homogeneously. Suitable emulsifiers include polyethylene glycol (PEG) chains and fatty acids. A combination of glycerol stearate and PEG 100 has been found to be particularly suitable. Up to 15 wt% of the composition may be the emulsifier component. The emulsifier component is typically water-soluble, and a suitable quantity of water (e.g. up to 15 wt%) may be included in the composition to dissolve the emulsifier component.

The dyestuff component provides a visual indicator that allows confirmation that the surface has been covered. Preferably, the dyestuff undergoes a colour change in the presence of the decontaminating composition concerned. For example, the dyestuff may be oxidised in the presence of an oxidising disinfectant. In one example, which is particularly useful when the decontaminating composition is a two-part system in which first and second parts react together to form a chlorine dioxide decontaminating composition, the dyestuff is an anthocyanin, anthocyanidin or betanin dyestuff, which undergo a colour change from a distinctive purple or red colour to colourless in the presence of chlorine dioxide.

Suitable dyestuffs are described in the present applicant’s International Patent Application No. WO 2022/013543 A1 , the contents of which are incorporated herein by reference. The dyestuff may for example be an anthocyanin dyestuff selected from the group consisting of: black carrot extract, purple carrot extract, haskapa berry extract, and blackcurrant extract. In a particularly preferred embodiment, the dyestuff comprises Black Carrot Extract (an anthocyanin dyestuff, also referred to as Antho Black Carrot Extract or AnthoCarrot). Examples of anthocyanidin dyestuffs that may be suitable for use include bilberry extract and blue pea extract (clitoria ternatea). Suitable betanin dyestuffs may be referred to as E162 food additives. Examples of betanin dyestuffs that may be suitable for use include red beetroot powder and beetroot juice concentrate.

The composition preferably comprises up to 10% of the dyestuff. The verification composition may include a preservative to inhibit the growth of mould and other contaminants. Any suitable preservative could be used. One suitable example is Parmetol BPX (a registered trade mark of Vink Chemicals GmbH & Co. KG, Kakenstorf, Germany), which is a blend of phenoxyethanol, butylbenzisothiazolone, and bis(3-aminopropyl)dodeclamine. The composition may for example comprise up to 2% of the preservative by weight, and more preferably comprises up to 1 % of the preservative by weight.

An example verification composition has the formulation:

% w/w soya wax 13 beeswax 14 castor oil 22 glycol stearate & PEG 100 11

Anthocyanin dye 9 water 11 isododecane 19 parmetol bpx 1

The above formulation has been found to provide a verification composition that is solid and stable at room temperature, and that can be easily spread by hand or by a lipstick-style applicator or a similar device onto a surface to leave an even, uniform coating of the verification composition. The anthocyanin dye in this instance is black carrot extract, which gives the verification composition a distinctive purple/red colour that changes to colourless after contact with chlorine dioxide. The spreadability of the verification composition can be temporarily increased by warming the composition by hand before application.

Further modifications and variations not explicitly described above can also be contemplated without departing from the scope of the invention as defined in the appended claims.

Claims

1 . A verification composition for application to a surface to be decontaminated, wherein the composition is a manually-spreadable solid at room temperature, and comprises:

- up to 50 wt% of one or more waxes;

- up to 25 wt% of one or more oils;

- up to 30 wt% of a solvent;

- up to 15 wt% of one or more emulsifiers; and

- up to 10 wt% of a dyestuff.

2. A verification composition according to Claim 1 , wherein the dyestuff undergoes a colour change in the presence of chlorine dioxide.

3. A verification composition according to Claim 1 or Claim 2, wherein the dyestuff comprises an anthocyanin, an anthocyanidin or a betanin dyestuff.

4. A verification composition according to Claim 3, wherein the dyestuff comprises black carrot extract.

5. A verification composition according to any preceding claim, wherein the or each wax is a non-petroleum based wax.

6. A verification composition according to Claim 5, wherein the wax or at least one of the waxes comprises a plant-derived wax.

7. A verification composition according to Claim 5 or Claim 6, wherein the wax or at least one of the waxes is selected from the group consisting of soya wax, palm wax, candelilla wax, carnauba wax, stearic acid, sunflower wax, and beeswax.

8. A verification composition according to Claim 7, comprising a blend of beeswax and soya wax.

9. A verification composition according to any preceding claim, comprising up to 40 wt% of the one or more waxes.

10. A verification composition according to any preceding claim, wherein the oil is selected from the group consisting of castor oil, olive oil, rapeseed oil, passionflower oil, sunflower oil, coconut oil and marula oil.

11. A verification composition according to any preceding claim, comprising up to 25 wt%, preferably up to 20 wt%, of the solvent.

12. A verification composition according to any preceding claim, wherein the solvent comprises isododecane or isohexadecane.

13. A verification composition according to any preceding claim, wherein the emulsifier or one of the emulsifiers comprises a polyethylene glycol (PEG) or a fatty acid.

14. A verification composition according to Claim 13, comprising PEG 100 and/or glycol stearate as an emulsifier.

15. A verification composition according to any preceding claim, further comprising a preservative.

16. A verification composition according to Claim 15, comprising up to 2 wt% of the preservative.

17. A verification composition according to any of Claims 1 to 4, comprising: between about 20 and about 40 wt% of wax in total, wherein the or each wax is selected from the group consisting of soya wax, palm wax, candelilla wax, carnauba wax, stearic acid, sunflower wax, and beeswax; between about 15 and about 25 wt% of oil in total, wherein the or each oil is selected from the group consisting of castor oil, olive oil, rapeseed oil, passionflower oil, sunflower oil, coconut oil, and marula oil; between about 5 and about 15 wt% of emulsifier in total, wherein the emulsifier is selected from the group consisting of glycol stearate, PEG 100, and mixtures thereof; between about 5 and about 15 wt% of the dyestuff; between about 5 and about 15 wt% water; and between about 15 and about 25 wt% of the solvent, wherein the solvent is selected from the group consisting of isododecane, and isohexadecane. A verification composition according to Claim 17, wherein: the wax is a blend of between about 10 and about 20 wt% soya wax and between about 10 and about 20 wt% beeswax; the oil is castor oil; the emulsifier is a mixture of glycol stearate and PEG 100; and the solvent is isododecane. In combination, a verification composition according to any preceding claim and a container, wherein the container comprises a tube housing and a block of the verification composition, arranged such that the block is extendable with respect to the housing. Use of a verification composition according to any one of Claims 1 to 18 for verifying the complete removal of the composition from a surface during decontamination. A method of verifying a decontamination procedure in which the decontamination procedure comprises applying a decontaminating composition to a surface using an applicator, the method comprising: before applying the decontaminating composition, applying to a whole area of the surface a verification composition according to any one of Claims 1 to 18; applying the decontaminating composition to the surface using the applicator, such that application of the applicator to the surface removes the verification composition; and inspecting the surface to verify that all of the verification composition has been removed. 22. A method according to Claim 21 , wherein the decontaminating composition comprises chlorine dioxide and the verification composition is in accordance with Claim 2, the method further comprising: after applying the decontaminating composition to the surface, inspecting the applicator to verify that the colour change has occurred.