NZ500596A - An acidic disinfectant composition comprising an anioninc surfactant and one or more biocides in an aqueous solution - Google Patents

Abstract

A disinfectant composition is outlined, comprising at least one anionic surfactant (0.25%-25& w/w) and one or more biocides thereby providing broad-spectrum biocidal activity, in an aqueous solution buffered at an acidic pH (2.5-4.5). The anionic surfactant may be either a sulfonic acid or an inorganic ester of sulfuric acid or phosphoric acid. The biocides comprise at least one organic biocide, including phenol, aldehyde and ketone compounds, and a monovalent, divalent or trivalent metal, such as lithium, potassium, zinc, copper or silver. The various formulations provided have applications ranging from general household use to applications where more stringent disinfecting activity criteria are required.

Description

A DISINFECTANT COMPOSITION Field Of The Invention The present invention relates to a disinfectant composition and more particularly, to a buffered acidic aqueous disinfectant composition incorporating one or more anionic 5 surfactants. Various formulations may be provided for applications ranging from general household use to applications where more stringent disinfecting activity criteria need to be met.

Background Of The Invention Recent changes to regulations relating '0 chemical disinfectants in various 10 countries around the world have led to a redefining of the standards used to classify such compositions, particularly with regard to the killing of blood borne pathogens. More particularly, a wider range of pathogens then previously employed is now used in the testing of disinfectants for classification as a high level disinfectant or chemical sterilant. To be classified as a chemical sterilant or a high level disinfectant for hospital use, 15 a disinfectant must be capable of destroying or otherwise inactivating a representative range of organisms classed as significant medical pathogens in each of the major test categories Such pathogens include spores of Bacillus subtillis or Clostridium sporogenes, Mycobacteria tuberculosis, Mycobacteria bovis and Mycobacteria terrae, viruses including Poliovirus type II, Parvovirus, Herpes simplex virus and adenovirus 20 group virus. Bactcria used in such testing include Staphylococcus aureus, Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa and Salmonella choleraesius. Fungus that may be used in testing include Trycophyton iriterdigitalae and Metagrayphydis. The tesiing involves exposing such pathogens to the disinfectant composition under internationally accepted wet suspension and dry film protocols.

In addition to meeting the extensive test criteria, it is desirable that a high level disinfectant or chemical sterilant have characteristics of being safe to use in. terms of 5 oral, vapour and contact toxicity, be safe to store and transport, and be chemically stable typically over a period of 2 years. It is also desirable thai the disinfectant composition be substantially non-damaging to surfaces with which it may routinely come into contact in use, be easy to dispense and be environmentally acceptable.

Many disinfectants currently available do not have the ability to either kill or 10 permanently inactivate the range of pathogens required to meet the standard for classification as a high level disinfectant or chemical sterilant. Disinfectants thai meet such standards generally contain chemicals hazardous to humans such as halogen releasing chemicals, strong oxidising agents and some aldehydes, particularly glutaraldehyde- Other such chemicals include ethylene oxide, chlorine dioxide, peracetic 15 acid and activated hydrogen peroxide. In many instances, the use of such disinfectants is restricted to enclosed environments due to their hazardous nature and their use is to be avoided on the grounds of toxicity and/or capacity for causing burning or irritation on contact.

Accordingly, there is a need for disinfectants having the ability to kill or inactivate 20 a broad spectrum of pathogens as required by current and emerging disinfectant standards, which are relatively environmentally friendly and less hazardous to use.

Summary Of The Invention It is an aim to ameKosate one or more of the problems of the prior ait or to at least provide a useful alternative disinfectant composition.

In one aspect of the invention there is provided a disinfectant composition 5 comprising at least one anionic surfactant and one or more biocides in an aqueous solution buffered at an acidic pH.

The or each anionic surfactant may be either a sulfonic acid or an inorganic ester of sulfuric or phosphoric acid, respectively.

Preferably, the anionic surfactant is a sulfonic acid or a sulfate or phosphate of an 10 alkane, an alkylbenzene an alkyl or dialkyl naptlialene, an alkyl diphenyl, an alkyl diphenyloxide. alkyl or alkyl aryl polyethoxylate or polypropylate containing from 2 to 12 molecules of either ethylene or propylene oxide.

The composition may also incorporate at least one biocide. Preferably, the composition will include a plurality of different biocides. The biocides may comprise at 15 least one organic biocide selected from the group consisting of phenol, aldehyde and ketone compounds. Preferably, the composition will include one or both of an aldehyde or ketone compound, and a phenol biocide compound.

In addition, the composition may also include a biocide selected from divalent and trivalent metals having known biocidal activity. Preferred such metals include zinc, 20 copper and silver. At least one monovalent metal may also be present that may or may not have biocidal activity. Usually, the monovalent metal ion will be lithium or potassium.

Typically, the buffer solution will be formed by one or more organic acids and water soluble salts thereof The organic acid(s) may be selected from hydroxy acids and carboxylic acids. Citric acid is a particularly preferred such organic acid and the water soluble metal salt thereof may comprise one or more of zinc citrate, copper citrate and 5 silver citrate. Accordingly, divalent and/or trjvalent metal salts having biocidal activity may be present as the salt of an organic acid. Alternatively, they may be incorporated in the form of their metal oxides.

Preferably, the composition will further comprise at least one non-ionic surfactant the choice of which will depend on the application in which the composition is to be (0 used.

In addition, the composition of the invention may include one or more polar solvents for solubilising the organic biocides and thereby facilitating miscibility.

The pH of the aqueous solution will usually be about 6.0 or less and preferably, will be in a range of from about 2.5 to about 4.5. The pH of the composition may be 15 adjusted to die desired level using a hydroxide, carbonate or bicarbonate of an alkali metal. The monovalent metal content of the composition therefore may be due to that added at the time of adjusting the pH of the composition alone, or in conjunction with the separate addition of monovalent metal(s). Preferably, the alkali metal will be lithium.

The use of a plurality of different biocides can provide broad-spectrum biocidal activity in the absence of the use of chlorine based oxidising agents and the like.

Maintaining the pH of the solution at an acidic level assists in retention of the charge of the or each anionic surfactant during use and thereby the effectiveness of the biocidal activity of the surfactants). More particularly, the ability of an anionic surfactant to solubilise lipids, while part of its cleaning action, also provides biocidal activity against a range of biocidal, viral and other pathogens. In providing the instant invention the present inventors have recognised that by buffering the pH of the disinfectant compositions at an acidic level the biocidal activity of the anionic surfactant(s) may be maximised.

Accordingly,the biocidal activity of the biocides can be complemented by that provided by the one or more anionic surfactants at the acidic pH of the composition, which may selected for their ability to degrade or inactivate pathogens, such as virus by disruption of the structural lipid outer membrane, resulting in inactivation or destruction of pathogens. Accordingly, an anionic surfactant in the composition can have a dual role; that of cleaning agent and biocide.

By "biocide" is meant an organic compound or divalent or trivalent metal capable of degrading, detoxifying, inactivating or killing one or more toxins, pathogens, microorganisms, and disease or sickness causative agents including mycobacteria, bacteria and bacteria spores, viruses, moulds, and microbes. The disease or sickness causative agents may be water or blood borne.

By '"biocidal activity" is meant the degrading, detoxifying, activating ox killing activity of a biocide or biocides.

A disinfectant composition of the invention may be formulated as a general household or commercial grade disinfectant, a hospital grade disinfectant or a chemical sterilant depending on the need. Accordingly, the composition allows for a broad range of disinfectants to be provided for meeting a given requirement, the grade of disinfectant being determined by the anionic surfactant(fe) and biocides(s) selected.

The disinfectant composition may be formulated to be used neat or for being diluted prior to use. Concentrated compositions may be diluted with a suitable solvent, 5 usually water, or a lower alkanol like ethanol or isopropanol, to a composition to solvent ratio of 1:49 and may be sprayed onto the surface to be cleaned, applied by way of an ultrasound technique or circulated over items to be treated.

Advantageously, embodiments of disinfectant compositions of the invention may provide required levels of biocidal activity with reduced use of toxic chcmicals such as Io peracetic acid, glutaraldehyde hydrogen peroxide and the such like.

By avoiding or reducing the use of strong oxidising and toxic agents, the safety of the disinfectant compostions may be enhanced relative to those that contain such chemicals or in which they are present in greater concentrations. Moreover, reduced use of hazardous chemicals allows for easier handling and greater disinfecting and cleaning 15 applications. Damage to susceptible surfaces may also be lessened while at the same time, adequate disinfecting of a surface achieved.

Unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise', 'comprising1, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense 20 of 'including, but not limited to".

The invention will now hereinafter be described with reference to a number of preferred non-limiting embodiments.

Delailed Description. Of Preferred Embodiments Of The Invention The or each anionic surfactanL may be either a foaming or non-foaming surfactant as required, respectively.

Generally, the anionic surfactant(s) will be selected on the basis of one or more of 5 the following characteristic's: (1) foaming propensity; (2) hydrophile-hydrophobe balance (HLB); (3) chemical stability at the pH of the disinfectant composition before and during use; (4) ability to contribute to the strength of the buffering capacity of the buffer solution; and (5) ability at the desired pH of the ultimate disinfectant composition to interact, react with or bind to charged groups on the surface of microbial and other 10 disease or sickness causative agents.

The biochemical reactivity of anionic surfactants is the opposite of the mechanism by which cationic surfactants such as lauryl dime thy Ibenzyl ammonium chloride act as a quaternary biocide, namely reacting with or binding to negatively charged chemical groups. Without being restricted to any particular theory or mode of action, the 15 reactivity of anionic surfactants of the disinfectant composition of the invention is believed to be enhanced in comparison with quaternary cationic surfactants, due to the strength of the negative charge in the preferred pH range of the instant composition.

\ The anionic surfactant(s) will preferably be selected from the group consisting of a sulfonic acid or a sulphate or a phosphate of a Cfi to CIS alkane, a C7 to C16 alkylbenzene, 20 a C3 to Cg alkyl or dialkyl napthalene, a C3 to C7 alkyl diphenyl or a C5 to C7 alkyl diphenyl oxide.

/ It will be appreciated that anionic surfactants such as disulfonic acids and the sulfuric or phosphoric esters of noil-ionic surfactants are within the scope of the invention.

Tlie combined total amount of the anionic surfactant(s) in the composition will generally be in a range of from about 0.25% to about 25% w/w of the composition.

The types of organic biocide and number thereof are selected on the basis of their biocidal activity at the desired pH level and their compatibility with other ingredients in the disinfectant composition in regard to miscibility, together with the type of biocidal activity required Generally, a plurality of organic biocides will be formulated into the composition to provide broad spectrum biocidal activity Each organic biocide may complement the mode of action of the anionic surfactant(s) and one or more other biocides in the composition, or act entirely independently of the anionic surfactants and other biocides to achieve the desired outcome.

Normally, a disinfectant composition will include at least one each of an aldehyde and a ketone organic biocide having broad biocidal activity. The biocides may be selected from ethancdiol (also known as glyoxal), glutaraldehyde, succindialdehyde, phthalaldehyde. 6-acetoxy-2-dimethyl-m-dioxane, hydroxymethyl-5, 5-diraethylhydajatoin, 1,2-bis(hydroxyl)-5,5-dimethyIhydantoin, 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one and other commercially available such compounds.

The phenol compound biocide will also normally be selected for broad biocidal activity. However, as will be appreciated, any of the organic biocides may be selected ibr Lheir activity against a particular disease or sickness causative agent, pathogen or other such target, or a specific class or type thereof. Phenol compounds are suitable for penetrating the outer protective membrane of many pathogens such as tubercular mycobacteria to exert biocidal activity and ou find particular application where enhanced 5 lipid solubility is desired. Phenol compounds are relatively efficient biocides and potentially more effective than either aldehyde or ketone compounds biocides against such pathogens.

The phenol compound(s) may comprise one or more of phenol, an alkyl phenol, o-phenylphenol and 2,4,4'-trichloro-2'-hydroxy-diphenyl ether and like compounds. 10 Preferably, the phenol compound is a mono Cj to C7 alkyl phenol, a C( to C4 diaikyl phenol, a mono or di-halogenated phenol, a halogenated mono C, to C7 alkyl or C[ to C7 di-alkyl phenol or a C| to C3 alkyl o-phenylphenol.

Normally, the or each aldehyde or ketone compound will be present in an amount of from about 0.1 % to about 5% w/w of the composition.

The or each phenol compound may be utilised at a concentration of from about 0-05% to about 5% w/w of the composition.

The organic acid(s) may comprise one or more of glycollic acid, citric acid, lactic acid, tartaric acid, ascorbic acid and salycilic acid. Other organic acids which display antimicrobial properties and so are commonly used as food preservatives may also be 20 utilized in the disinfectant composition, including acetic acid, propionic acid, undecanoic acid 2.4-hexanedienic acid, benzoic acid, dehydroacetic acid and p-hydroxybenzoic acid. Such "food acids" have been shown to be capable of interfering with microbial uptake of substrates (Freese et al, Nature 1973; 241: 321-325), when appropriately formulated.

The total combined concentration of the organic acid(s) in the composition will normally be in a range of from 0.25% to 15% w/w of the composition.

The monovalent metal(s) may be contributed by the salt of the organic acid and/or be added during ad justment of the pH of the disinfectant composition to the desired 5 level Preferably, the pH will be in a range of from about 2.5 to about 4.5.

Increase in pH may be achieved with the use of the hydroxide, carbonate and bicarbonate forms of alkali metals which will generally be added with continuous stirring. Lithium hydroxide and potassium hydroxide are preferred.

Lithium may contribute to the total biocidal activity of the composition due to its 10 potential for interfering with or disrupting sodium-potassium ion transfer mechanisms and equilibria across cell walls so that cellular processes are thereby interrupted. Accordingly, the addition of lithium is desirable in compositions where stringent disinfecting capability is required. In compositions where less stringency is needed, potassium may be used as a total or partial replacement for lithium. Generally, no less 15 than one half of the alkali metal in a composition will comprise lithium.

Divalent and trivalent metals are also capable of providing biocidal activity. In particular, zinc, coppcr and silver when incorporated in a water soluble form can have anti-microbial activity and may be effective against larger water borne organisms as well as fungi and yeasts. Zinc is particularly preferred for providing biocidal activity in 20 compositions for cleaning up faeces, urine, whole blood and other body fluids in the hospital environment that may potentially be infected with harmful pathogens including viruses such as Hepatitis B and HIV.

- SI - Such metals may also be taken up into cells of fluid borne pathogens at toxic levels. The amount used in compositions of the invention will vary depending on the meial and the purpose of a given composition and can be readily determined using any suitable standard method known to the skilled addressee.

In suitable compositions zinc, copper and or silver metals may be incorporated as water soluble sails of organic acids. Citrate salts are particularly preferred. In this instance, zinc citrate may be present in an amount of from about 0.01% to 1% w/w of the composition, copper citrate in an amount of f'om 0.001 % to 0.25% w/w of the composition and silver citrate in an amount of from 0.001 % to 0.10% w/w of the 10 composition.

A small quantity of a strong organic acid may optionally be incorporated to supplement the surface activity of the anionic surfactant. This can assist in displacing dried proteinaceous residues and soils from surfaces. Generally, the organic acid will be phosphoric acid. Other suitable acids like glycolic acid may also be used for this J 5 purpose.

Desired characteristics such as viscosity, solubilisation of biocides. foaming and cleaning capabilities of the disinfectant compositions can be provided by one or more nonionic surfactants and viscosity modifiers such as acrylic polymers. In addition one or more of conventionally known dyes, opaciiiers, perfumes, odour control agents, 20 coiTosion inhibitors, antioxidants, and organic thickening agents may be incorporated into the composition of the invention. The amounts of each will again be dependent on the required outcomc and can be readily determined by the skilled addressee.

Polar solvents may be utilised to assist in solubilizing organic biocides and for stabilizing the composition. Such solvents may be selected from a lower C, lo C7 alkanol like methanol, ethanol or isopropanol, a mono, di or polyglycol, an ester or ether containing up to 7 carbon atoms, and a suitable pyrollidonc. Hie total amount of polar 5 solvent a disinfectant composition will usually be between about 2.5% and 25% w/w of the composition.

The invention will further be described by way of a number of examples of disinfectant compostions. Unless otherwise stated, all amounts of the ingredients of the exemplified compositions are expressed as w/w % of the composition. Diluted solutions 10 used to formulate the compositions are aqueous solutions.

Example 1 A composition for killing or rendering inactive bacteria, virus or other pathogen capable of causing a nosocomial infection and which is suitable for use in disinfecting surgical instruments is set out below.

Test Composition 1 Ingredient Amount Water 50 0 ^Dowfax 3B2 7.5 (Citric Acid, Anhydrous 4.5 Qlycollic Acid, 70% 3.0 p^phenylphenol 0.15 Gtfutaraldhyde 50% 0.25 \dthium hydroxide, 10% solution ' - to pH 4.5 to 5.0 -Triethyleneglycol 0.8 xdobanol 918 0.125 \Zmc Glycollate 0.15 ■Silicone Defoamer 0.002 Xscorbic acid 0.05 p6rrosion Inhibitor 0.02 Water to 100.0% To prepare the composition, one quarter of the anionic surfactant Dowfax 3B2 (available from Dow Chemicals Inc., LISA) is mixed with the anhydrous citric acid, glycollic acid and the o-phenylphenol in water and is stirred until the phenol compound has dissolved. Subsequently, die triethyleneglycol, glutaraldehyde solution and the nonionic surfactant Dobanol 918 (available from Shell Chemicals Inc, USA) together with the silicone defoamer and corrosion inhibitor (Teric 4590 available from ICI Ltd, Sydney Australia) are added to the solution, followed by the bulk of the remaining water. The pH of the resulting solution is then adjusted slowly with continuous stirring by adding lithium hydroxide. Subsequently, the zinc glycollate and ascorbic acid (used as an anti-oxidant) arc dissolved in the remaining water and added to the solution. The pH of the solution is then chccked and adjusted with lithium hydroxide to between 4.5 to 5.0 The composition can be heated to 45°C in a ventilated safety cabinet if fast disinfecting action is required. When used at room temperature, it can be safely used in an open vessel provided the room is well ventilated.

Example 2 A composition of the invention suitable for use as a bathroom and toilet disinfectant-cleaner is shown below. The ccriposilion is prepared in the manner as for Example 1. However, the final pH is adjusted to level from 3.5 to 4,0 with potassium hydroxide. The composition may be used either neat (undiluted) or diluted with up to 9 parts of water, ie a 1:9 ratio of disinfectant composition to water.

Test Composition 2 Ingredient Amount Water 50.0 .Linear C8~CI4 benzene sulphonic acid 6.0 /Phosphoric acid, 85% 4.0 /Lactic acid, 100% 3.5 /Cjlycollic acid, 70% 5-0 3-methyl methoxybutanol 7.5 ^Lithium hydroxide, 10% 9.5 potassium hydroxide, 50% to pH 3.0 to 3.5 Lauryl ethersulphate, 70% 2.5 Zinc Glycollate 0.25 PKenol, 90% 1.1 ^acetoxy-2-dimethyl-n-dioxane 0.35 Water to 100% 6-acetoxy-2-dnnehtyl-n-dioxane is available under the trademark Givgard DXN from Ciba Geigy Inc, USA.

Example 3 Tills composition is a general purpose disinfectant-detergent and is again prepared in the above manner. The para tertiary arnylphenol is dissolved in the sulfonic acid surfactant with the aid of the propyleneglycol monomethylether solvent. The pH of the composition is monitored continuously to ensure thai it does not exceed 5.0 at any time during preparation. The pH is adjusted to the final level of between 4.0 to 5.0 with the potassium hydroxide.

The composition can also be used neat but generally will be routinely diluted with up to 19 parts wilh tap water when used as disinfectant-detergent for surface cleaning. -chloro-2-methyl-4-isothiazolin-3-one is used as a biocide and is available under the trade mark Kathon 886 available from Rhon & Haas Inc., USA Teric 306 is a nonionic surfactant available from ICI Ltd, Sydney, Australia.

Test Composition 3 Ingredient Amount Water 65.0 C3-C7 dialkyl naphthalene sulphonic acid 6.0 Para tertiary arnylphenol 0-25 Propyleneglycol monomethylether 6.5 Citric acid, 100% 6.0 Phosphoric acid, 85% 3.5 Benzoic acid, 100% 1.5 Lithium hydroxide, 10% solution 9-0 Potassium hydroxide, 50% solution to pH 4.0 to 5.0 Teric 306 1.5 Kathon 886 0.35 Copper acetate 500 ppm Silver citrate 50 ppm Water to 100.0% Example 4 Test compositions 1 and 2 were evaluated for their biocidal activity against Hepatits B virus (HBV) and HIV in whole blood and the outcome compared to the activity found for several conventional commercially available disinfectants. The results are shown in Table 1. The main active of the comcrcial disinfectants is also indicated.

Table 1: Comparative Testing Of Disinfectants In Whole Blood Disinfectant Strength Time Virus (mins) HBV HIV Aidal Plus UV1 glutaraldehyde 2% Neat 1 Pass Pass Peracetic Acid 0.45% Fail Fail Demestos1M Neat Pass nt hyperchlorite 5000 ppm Fail Fail Milton™ 5000 ppm Fail nt hyperchlorite Viraclean ™ Neat Fail Pass quaiemary-glycol Test composition 1 1:4 1 Pass Pass Test composition 2 1:4 1 Pass Pass Virkon™ persulphate 1% nt Fail Clearsol™ phenolic 2% nt Fail Phensol1M phenolic 4% nt Fail As can be seen, the test compositions were found to provide effective biocidal activity against both HBV and HIV. Only the 2% glutaraldehyde containing (Aidal Plus™) compositions tested was effective against both viruses.

The concentration of the hyperchlorite dilutions of Demestos™ and Milton™ are expressed in ppm of available chlorine. Viraclean™, Phensol™ and Aidal Plus™ disinfectants are available from Whiteley Industries Pty Ltd, Sydney, Australia. Clearsol™ is available from Coventry Chemicals Limited, United Kingdom.

Although test composition 1 contains 0-25% w/w glutaraldehyde, it is considered to have less vapour toxicity compared to Aidal Plus™ and so is suitable as a replacement 5 for the more toxic 2% glutaraldehyde preparations.

Example 5 The biocidal activity of test compositions 1 and 2 and for Aidal Plus ™ disinfectant against B. subtilis spores at room temperature is indicated in Table 2.

Table 2: Spore Killing Time Of Disinfectants Disinfectant Dilution Kill Time (mins) Aidal Plus .Neat 180 Test composition 1 Neat 90 Test composition 2 1:4 120 Both test compositions 1 and 2 were found to have effective biocidal activity against the spores and indeed, their killing times were markedly reduced compared to the T*J chemical sterilant Aidal Plus . Accordingly, the test compositions demonstrated improved biocidal activity against the comparative 2% glutaraldehyde disinfectant constituting a useful and practical advance in such formulations.

Although the present invention has been described hereinbefore with reference to a number of preferred embodiments, the skilled address will appreciate that the numerous 20 variations and modifications are possible without departing from the scope of the invention.

Claims (22)

V * 19 - THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS

1. A disinfectant composition comprising at least one anionic surfactant and one or more biocides in an aqueous solution buffered at an acidic pH. 5

2. A disinfectant composition according to claim 1 wherein the or each anionic surfactant is cither a sulfonic acid or an inorganic ester of sulfuric or phosphoric acid, respectively.

3. A disinfectant composition according to claim 2 wherein the anionic surfactant is a sulfonic acid or a sulphate or a phosphate of an alkane, an alkylbenzene an io alkyl or dialkyl napthalene, an alkyl diphenyl, an alkyl diphenyloxide, alkyl or alkyl aiyl polyethoxylate or polypropylate containing from 2 to 12 molecules of either ethylene or propylene oxide.

4. A disinfectant composition according to claim 3 wherein the anionic surfactant is a sulfonic acid or a sulphate or a phosphate of a Cg to C18 alkane, a C7 to C,6 15 alkylbenzene, a C3 to C8 alkyl or dialkyl napthalene, a C3 to C7 alkyl diphenyl or a C3 to C7 alkyl diphenyl oxide.

5. A disinfectant composition according to any one of claims 1 to 4 wherein the combined total amount of the at least one said anionic surfactant in the composition is from 0.25% w/w to 25% w/w of the composition. 20

6. A disinfectant composition according to any one of claims 1 to 5 comprising a plurality of different said biocides.

7. A disinfectant composition according to claim 6 wherein the biocides comprise at least one organic biocide selected from the group consisting of a phenol compound, an aldehyde compound and a ketone compound. -20-

8. A disinfectant composition according to claim 7 wherein the biocidcs comprise one or both of an aldehyde or ketone compound, and a phenol compound.

9. A disinfectant composition according to claims 7 or 8 wherein the aldehyde compound is selected from the group consisting of ethanediol, glutaraldehyde, 5 succindiajdehyde and phthalaldehyde.

10. A disinfectant composition according to any one of claims 7 to 9 wherein the ketone compound is selected from the group consisting of 6-acetoxy-3-dimethyl-m-dioxane, hydroxyrnethyl-5,5-dimehtylhydantoin, 1,2-bis(hydroxyl)-5,5-dimehtylhydantoin, 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4- 10 isothiazolin-3-one.

11. A disinfectant composition according to any one of claims 7 to 10 wherein the phenol compound is selected from the group consisting of phenol, o-phenylphenol and 2,4,4'-trichloro-2'-hydroxy-diphenyl ether.

12. A disinfectant composition according to claim 11 wherein the phenol compound 15 is a mono C| to C7 alkylphenoJ, a Q to C4 dialkyl phenol, a mono or di- halogenated phenol, a halogenated mono Cj to C7 alkyl or C, to C7 di-alkyl phenol, or a C, lo C3 alky] o-phenylphenol.

13. A disinfectant composition according to claim 8 wherein the or each aldehyde or ketone compound is present in the composition in an amount of from about 0.1% 20 to 5% w/w of the composition.

14. A disinfectant composition according to any one of claims 8 to 13 wherein the or each phenol compound is present in the composition in an amount of from 0.05% to 5% w/w of the composition. -21 -

15. A disinfectant composition according to any one of claims 1 to 14 comprising at least one biocide selected from divalent arid Irivalent metals.

16. A disinfectant composition according to claim 15 wherein the metals comprise zinc, copper and silver. 5

17. A disinfectant composition according to any one of claims 1 to 14 wherein the buffer solution comprises one or more organic acids selected from hydroxy acids and cafboxylic acids and water soluble metal salts thereof.

18. A disinfectant composition according to claim 17 wherein the or each organic acid is selected from the group consisting of glycollic acid, citric acid, lactic acid, 10 tartaric acid, salycilic acid and dehydroacetic acid.

19. A disinfectant composition according io claim 17 or 18 wherein the at least one organic acid is present in the composition in a total amount of from 0.25% to 15% w/vv of the composition.

20. A disinfectant composition according to claim 17 wherein the or at least one of 15 the water soluble salts is a zinc, copper or silver salt of the organic acid or organic acids.

21. A disinfectant composition according to claim 17 wherein the water soluble metal salts comprise one or more of zinc citrate in an amount of from 0.01% to 1% w/w of the composition, copper citrate in an amount of from 0.001% to 20 0.25% w/w of the composition and silver citrate in an amount of from 0.001% to 0.10% w/w of the composition.

22. A disinfectant composition according to any one of claims 1 to 21 further comprising at least one alkali metal. 00596 -22- 24. 5 25. 26. 10 27. 28. 29. A disinfectant composition according to any one of claims 1 to 21 further comprising at least one hydroxide, carbonate or bicarbonate of an alkali metal. A disinfectant composition according to claims 22 or 23 wherein the alkali metal is selected from lithium or potassium A disinfectant composition according to any one of claims 1 to 24 further comprising one or more non-ionic surfactants in a total amount of from 0.25% to 5.0% w/w of the composition. A disinfectant composition according to any one of claims 1 to 25 further comprising at least one polar solvent for enhancing miscibility. A disinfectant composition according to claim 26 wherein the at least one polar solvent comprises one or more of a C| to C7 alcohol, a mono, di or poly glycol, an ester or ether having up to 7 carbon atoms, and a pyrollidone. A disinfectant composition according to claim 26 or 27 wherein the total amount of the polar solvent in the composition ts from 2.5% w/w to 25% w/w of the composition. A disinfectant composition according to any one of claims 1 to 28 wherein the aqueous solution has a pH of 6.0 or less. A disinfectant composition according to claim 29 wherein the pH of the aqueous solution is in a range of from 2.5 to 4.5. INlELLECTUAl PROPERTY 0FFICF GF NZ 1 9 OCT 1939 059 ABSTRACT There is provided a disinfectant composition comprising at least one anionic surfactant and one or more biocides in an aqueous solution buffered at an acidic pH. The or each anionic surfactant may be either a sulfonic acid or an inorganic ester of sulfuric or phosphoric acid, respectively.