WO2008040987A2

WO2008040987A2 - Biocidal formulation

Info

Publication number: WO2008040987A2
Application number: PCT/GB2007/003776
Authority: WO
Inventors: Thomas David Evans; Timothy Mark Howe
Original assignee: Bio Technics Limited
Priority date: 2006-10-04
Filing date: 2007-10-04
Publication date: 2008-04-10
Also published as: GB0619592D0; WO2008040987A3

Abstract

A water soluble biocidal formulation comprising iodide salt in an amount of 1 -20% w/w, an amount of 25-95% w/w of peroxodisulphate as an oxidising agent; an amount of 1 -30% w/w acetate salt; and an amount of diluents to make the concentration of the formulation up to 100% w/w.

Description

BIOCIDAL FORMULATION

Field of Invention

The invention relates to biocidal formulations. By biocidal we mean a substance which is capable of killing living cells or organisms. Such organisms include cellular or multi-cellular prokaryotes or eukaryotes such as bacteria and fungi (also including spores) and non-cellular nucleic acid containing infective agents such as viruses.

For generations, bleaching and sanitising agents have been used for domestic and industrial cleaning and include the use of liquid sodium hypochlorite (domestic bleach), calcium hypochlorite (bleaching powder), peracetic acid, peroxomonosulphates and hydrogen peroxide. Such products are generally marketed as powders and/or liquids. Liquid hypochlorites, in particular, are very strongly caustic and can release chlorine if acidified. Further, such liquid products are inherently unstable, corrosive and readily inactivated by organic matter, thus limiting their usefulness and reliability. On the other hand whilst powder products are more stable they are less reactive.

There is extensive prior art describing various compositions which set out to provide various stable acid systems such as that described in GB 932750. However, compositions made in accordance with that patent were found to be highly unstable in the powder state and liberated chlorine gas within a short period of manufacture. This was found to be due primarily to the inclusion of high concentrations of sulphamic acid and mineral acid salts which had been added to achieve an exact level of acidity. Subsequently GB 2078522 sought to overcome the deficiencies found in GB 932750 by introducing a minimal level of sulphamic acid as a chlorine acceptor and achieved the desired level of acidity at in-use dilution by using a non-reducing acid such as an organic acid like malic acid or succinic acid or, alternatively, by use of an acid phosphate salt combination with a sulphamic acid acceptor. Such a composition produced a relatively stable powder system which did not liberate chlorine gas when stored for prolonged periods at 37⁰C nor did it appear to liberate chlorine gas when the product was dissolved in water at approved dilutions. Chlorine was however liberated if the product was stored in damp conditions or instructions were not followed and concentrated solutions are made up.

EP0260293 and GB2187098 both set out to further improve on the abovementioned compositions by providing a biocidal composition which is specifically resistant to chlorine generation not only at approved dilutions but also in conditions in which only a small amount of water was present. Such compositions were especially targeted for use in foreign environments where such conditions easily occur. Examples of such are where water may be spilt on the composition, for example in external environments or instructions for making up the composition were not followed so that concentrated solutions were generated. EP0260293 particularly is based around the use of a triple salt of potassium hydrogen peroxymonosulphate, potassium hydrogen sulphate and potassium sulphate as main active ingredient.

Finally GB2164851 describes a virucidal composition with improved stability and resistance and forms the basis for the commercially available product VIRKON®. The composition is based around a commercially available triple salt which includes approximately by weight 45% potassium monopersulphate, 25% potassium hydrogen sulphate and 30% dipotassium sulphate. The composition apparently utilises a synergistic effect between the potassium monopersulphate and small quantities of chloride ions. The resulting in situ generation of low levels of hypochlorite is claimed to increase the efficiency of the product without the hazard of potential chlorine release at low pH. The disadvantage of such compositions is that they have to be made in acid form since the monopersulphate is manufactured as the triple salt outlined above. Additional acids in powder form were also included in the final composition.

Object of the Invention

The aim of the present invention is to provide an improved biocidal formulation which is capable of killing fungi, spores, bacteria and viruses, all to significant levels but which remains stable, does not release toxic gas emissions and leaves no residues.

Summary of the Invention

According to the invention there is provided a water soluble biocidal formulation comprising iodide salt in an amount of 1-20% w/w, an amount of 25-95% w/w of peroxodisulphate as an oxidising agent; an amount of 1- 30% w/w acetate salt; and an amount of diluents to make the concentration of the formulation up to 100% w/w.

According to a second aspect of the invention inclusion of any one or more of the diluents may be optional.

Preferably, the iodide salt is present in an amount of 1 -10 % w/w of iodide salt. The peroxodisulphate may be present an amount of 40-95% w/w. Further the acetate salt may be present in an amount of 1 -20% w/w. Optimally, the iodide salt is present as potassium iodide salt in an amount of 4% w/w. The peroxodisulphate is present as potassium peroxodisulphate in an amount of 30-50% w/w. Additionally the acetate salt may be present as sodium acetate in an amount of 6% w/w.

The diluents may comprise any one or more of the group selected from surfactants, organic acids, buffering agents or sulphamic acid.

Preferably, the diluents present comprise a surfactant, at least one organic acid, buffering agent or agents and sulphamic acid.

Generally, the diluents are present in the formulation in an amount of 5- 10% w/w surfactant; 5-15% w/w of at least one organic acid; 10-30 % w/w buffering agent and 0-25% w/w of sulphamic acid.

More preferably, the diluents are present in the formulation in an amount of 5-10% w/w surfactant; 5-15% w/w of at least one organic acid; 10-25 % w/w buffering agent and 0-10% w/w of sulphamic acid.

Most preferably, the surfactant is present in an amount of 10%; at least one organic acid present in an amount of 5-15% w/w; buffering agent in an amount of 15-25 % w/w; the sulphamic acid in an amount of 0-5% w/w.

Advantageously, the biocidal formulation when in solution, buffers around an acidic pH with the most preferred being between pH 3 and 4.

Any surfactant (wetting agent) compatible with the acids and oxidising agents can be utilised in the formulation but is preferably an ionic surfactant selected from the group consisting of alkyl benzene suphonates, alkyl sulphates, alkyl sulphonates, alkyl ethoxysulphates, and the like. However, preferably, it is sodium dodecylbenzene sulphonate and advantageously, 80% sodium dodecylbenzene sulphonate.

As an alternative to iodide salt, a water soluble bromide salt can be used. The most preferred salts are potassium or sodium with potassium iodide and potassium bromide being the preferred salts.

In an alternative aspect, the iodide salt may be excluded from the formulation and the levels of diluents increased to make the concentrate of the formation up to 100% w/w

Preferably, the organic acids are one or both of succinic and malic acid.

Advantageously, the buffering agent is capable of acting as a soil dispersant, and can be any salt, ester or anion of phosphoric acid such as an alkali metal phosphate, which is additionally capable of sequestering heavy metal ions. Use of such an agent additionally promotes surface contact thereby increasing the accessibility of the formulation to the area to be cleaned due to it working with the surfactant to lower surface tensions and disperse dirt/soil. The most preferred phosphate as a buffering agent is sodium hexametaphosphate.

In the alternative, the buffering agent can be provided in the form of an ammonium salt of phosphoric acid such as monoammonium phosphate.

The water soluble peroxodisuphate which is used as an oxidising agent can be any soluble peroxodisulphate and may include ammonium peroxodisulphate and potassium peroxodisulphate. The preferred peroxodisulphate is sodium peroxodisulphate due to the fact that the sodium salt therein degrades to sodium sulphate which is routinely present in potable waters anyway.

Any acetate salt can be used but is preferably, sodium acetate for the same reasons as above.

Preferably, the water soluble biocidal formulation is provided as a dry powder to be made up in water at point of use. Generally, at point of use approximately 100g of the dry formulation is dissolved in 10 litres of water.

A further aspect of the invention provides a water soluble biocidal formulation comprising peroxodisulphate in an amount of 25-95% w/w; an amount of 1-30% w/w acetate salt; and an amount of diluents to make the concentration of the formulation up to 100% w/w.

Embodiments of the invention

According to the present invention there is provided a biocidal formulation in which an example of one embodiment of the invention is shown and which was prepared by mixing together the following ingredients:

80% Sodium dodecylbezene sulphonate 10% w/w

Sodium hexametaphosphate 15% w/w

Malic Acid 10% w/w Sulphamic Acid 5% w/w

Sodium Acetate 6% w/w

Potassium iodide 4% w/w

Sodium peroxodisulphate 50% w/w Such a composition provides the advantage that there is no gas given off when in use. Further, although iodine normally stains, the use of potassium iodide in conjunction with sodium peroxodisulphate as an oxidising agent, in fact, means that as the reaction continues the iodine stain disappears. Therefore, when first used there is a brown/yellow tinge such that you can see where you have used the product but latterly, that disappears as the final products of the reaction are colourless.

Peroxodisulphates have not been used extensively in disinfectants in the past because of their hazard classification in Class 5.1. Sodium peroxodisulphate in particular has been known for years as a free radical generator but has not generally been used as a biocide because of its hazard classification and its perceived slow kinetics. Certainly, the manufacturers of such compounds indicate that use of such compounds as biocidal agents is very much considered a secondary application.

However, the present invention effectively and safely utilises sodium peroxodisulphate as the primary biocide with generation of iodine as one of two additional ancillary mechanisms to make a triple action biocide. Such utilises the higher oxidation potential of peroxodisulphate (E⁰ 2.01V) and in use in the formulation of the present invention generates both iodine and peracetic acid at low concentrations in situ which act as additional mechanistic routes to enhance the performance of the biocide formulation as a whole. Such use of peroxodisulphate provides a safe but powerful biocide formulation. The triple action of the formulation is due to the specific blend of oxidisers, oxy-acids and idophors which together generate free radicals for optimal destruction of pathogenic DNA and RNA. Sodium peroxodisulphate used in accordance with the present invention has shown to be a strong oxidising agent in terms of thermodynamics. Further, due to the free radical mechanisms involved, it has shown that when in combination with the other ingredients of the formulation, it has a disruptive effect on DNA and RNA providing the biocidal formulation with wide ranging and effective biocidal properties. The inclusion of sodium acetate in the formulation along with potassium iodide produces iodine and peracetic acid in situ in solution. Eventually, sodium iodate is produced as a product of the reaction which is colourless so no staining remains. Further, the oxidising agent used in some of the prior art is in a complex sulphate salt (triple salt) which is inherently acidic. On the other hand, the sodium peroxodisulphate of the present invention is not inherently acidic and the formulation utilises the organic acids(s) therein to lower the pH which allows peracetic acid rather than sodium peracetate to be formed. Consequently, the formulation is self buffering around pH 2.5- pH 3.5 although optimally around pH 3.2.

The advantage of the formulation of the present invention comprising sodium peroxodisulphate is that with its high oxidation potential of (E⁰ 2.01V), oxidation of iodide to iodine is much slower and thus, more effective in biocidal terms than in other reactions such as, for example, the formation of iodine using peroxomonosulphate (E⁰ 1.44V). In such, a reaction peroxomonosulphate would oxidise iodide quantitatively and more or less instantaneously thus, resulting in a short-lived biocidal effect.

The formulation is generally for use at temperatures of between 10-50^°C but with the optimum activity being around room temperature for example about 20^°C, where both the solution life and activity\are good. However, it can be used outwith these temperatures whereby just the length of activity is affected i.e. it works more slowly, for example, at low temperatures. It is envisaged that the biocidal formulation primarily will be for use indoors such as in hospitals, clinics, institutions and the like.

The effectiveness of the formulation, as described above, was tested by carrying out standard suspension tests. Such tests follow a recognised approach to disinfectant validation which is the CEN (European

Committees for normalisation) 216 work programme and provides a systematic approach to the testing of disinfectants. From this, a number of

BS EN methods have been derived for which there are clearly defined pass criteria.

Using BS EN 1276 which is a quantitative suspension test for the evaluation of bacterial activity of chemical disinfectants and antiseptics used in food, industrial, domestic and institutional areas, the efficacy of the formulation of the present invention was tested. A test suspension of bacterial spores, which in this case were spores of Clostridium perfringens, in a solution of interfering substances (Bovine Albumin 0.3g/l) was added to a prepared sample of the biocidal formulation to be tested diluted in hard water. The mixture was maintained at 20^°C for 30 minutes after which an aliquot of solution was taken and the bacterial action neutralised or suppressed. The agar used for maintaining the culture was clostridial agar. The number of surviving bacterial spores was then determined and the reduction in viable count calculated. The pass criteria for the test are > log 5 reduction.

VIRKON® was used as an industry standard and means of comparison with the test formulation and the test was carried out in duplicate. A control was also included which had no disinfectant or antiseptic present. The biocidal formulation of the present invention and that of VIRKON® were introduced as a 1 % solution in which dry powder was dissolved in potable water.

The results of this test are shown in Table 1 below.

Table 1 Number of viable spores

Test 1 Test 2

Control culture 1.2x10⁶ 1.7x10⁶

1 % VIRKON® solution 1.3x10⁵ 8.6x10⁴

1% Test formulation <10 30

The first test shows the VIRKON® solution giving a reduction of less than Log 1 whilst the test composition showed a log reduction of >Log 5. The second test showed VIRKON® a less than Log 2 reduction whilst the test composition showed a log reduction of >Log 4. These two tests illustrate that the test formulation of the present invention is much better at killing spores than the industry standard VIRKON®. Spores were chosen for the comparative test as they are ordinarily very difficult to kill using disinfectants.

According to the results in Table 1 , it can be seen that the formulation of the present invention provides improved results over the current market leader VIRKON®.. This is supported by other suspension tests. Tests under EN 1650 (under clean conditions) were carried out. EN 1650 is identical in principal to BS EN 1276 but Candida albicans (ATCC 10231) and Aspergillus niger (ATCC16404) are the organisms specified for use therein. The key points of difference in EN 1650 from 1276 are that a malt extract agar (in this case sabouraud dextrose agar) is used in place of tryptone soya agar and the incubation conditions are suited for fungi. Accordingly, EN 1650 provides a quantitative suspension test for the evaluation of fungal activity of chemical disinfectants and antiseptics used in food, industrial, domestic and institutional areas by which the efficacy of the formulation of the present invention was tested. Separate test suspensions of Candida albicans and Aspergillus niger each in a solution of interfering substances (Bovine Albumin 0.3g/l) were added to separate prepared samples of the biocidal formulation to be tested diluted in sterile filtered solutions of BSA. The respective mixtures were maintained at 20^°C for 30 minutes after which an aliquot of each solution was taken and the bacterial action neutralised or suppressed. The number of surviving yeast cells or mould spores was then determined and the reduction in viable count calculated. The pass criteria for the test are > log 4 reduction.

The results were both a pass with results of >Log 5 and >Log 4 for the Candida albicans and Aspergillus niger, respectively.

A number of further suspension tests were carried out under EN 1276:1997. As already indicated above, EN 1276 is a quantitative suspension test for the evaluation of bactericidal activity of chemical disinfectants and antiseptics used in food, industrial, domestic and institutional areas. In these particular experiments, a test suspension of bacteria in a solution of interfering substances (Bovine Albumin 0.3g/l) was added to a prepared sample of the biocidal formulation (1% w/v) to be tested and diluted in hard water. The agar used for Clostridium difficile was clostridial agar, whilst that used for the others was tryptone soya agar.

The mixture was maintained at 20^°C for 5 minutes after which an aliquot of solution was taken and the bacterial action neutralised or suppressed. The number of surviving bacteria was then determined and the reduction in viable count calculated. The pass criteria for the test are ≥ log 5 reduction.

The results obtained are shown in Table 2.

Culture Table 2 Result

Enterococcus hirae (ATCC 10541 ) > Log 6

Staphylococcus aureus (ΑTCC6538) >Log 6 Escheήcia coli (ATCC 10536) >Log 6

Pseudomonas aeruginosa (NCIMB10421 )^* >Log 6

Campylobacter jejuni (NCTC 11322) >Log 6

Listeria monocytogenes (NCTC11994) >Log 6

Proteus vulgaris (NCIMB 4175) >Log 6 Clostridium difficile (NCTC11209) >Log 5

The contact time for Pseudomonas aeruginosa was 15 minutes rather than 5 minutes.

From the results shown in Table 2, all cultures of bacteria exposed to the test formulation were significantly reduced and certainly by more than the expected pass criteria. Generally, as a comparison standard household disinfectants give results around >Log 3.

Additionally, tests under BS EN 14476 were carried out. These are virucidal quantitative suspension tests for chemical disinfectants and antiseptics used in human medicine. In these particular experiments, a mixture of 0.8ml of the 1 % w/v dilution of the test formulation and 0.2ml of Poliovirus 1 (Chat strain) ATCC VR-1562 suspension was prepared. Also included in the final test solution were interfering substances in the form of 0.6g/l foetal bovine serum which was added to a prepared sample of the biocidal formulation to be tested, diluted in sterile hard water. The mixture was maintained at 20^°C for 5 minutes after which an aliquot of solution was taken and the viral activity neutralised or suppressed. The effective viral activity was then determined under clean conditions. The pass criterion for the test is ≥ Log 4. The formulation under test showed effective virucidal activity at 5 minutes with results of >Log 5.

The same test was also carried out for Adenovirus 5 ATCC VR-5, again under clean conditions in which the pass criterion for the test is ≥ Log 4. The formulation under test showed effective virucidal activity at 5 minutes with results of >Log 5 (i.e. Log 5.67at 1% w/v of test formulation).

Standard test methods were also carried out to test for efficacy of the test formulation against viruses in suspension. Such test methods were carried out on Feline Calicivirus (as a Human Norovirus surrogate) and Bovine Viral Diahorrea Virus (as a Hepatitis C virus surrogate). In these particular experiments, a mixture of 0.9ml of the 0.5% w/v dilution of the test formulation and 0.1 ml of Feline Calicivirus suspension was prepared. Also included in the final test solution were interfering substances in the form of 0.6g/l foetal bovine serum which was added to a prepared sample of the biocidal formulation to be tested diluted in sterile hard water. The mixture was maintained at 20^°C for 5 minutes after which an aliquot of solution was taken and the viral activity neutralised or suppressed. The effective viral activity was then determined under clean conditions. The pass criterion for the test is ≥ Log 4. The formulation under test showed effective virucidal activity with 0.5% w/v of test formulation at 5 minutes with results of Log 4.18. Also a mixture of 0.9ml of the 0.5% w/v dilution of the test formulation and 0.1 ml of Bovine Viral Diahorrea Virus (ATCC VR-1422)-Hepatitis C virus surrogate was prepared. Also included in the final test solution were interfering substances in the form of 0.6g/l foetal bovine serum which was added to a prepared sample of the biocidal formulation to be tested diluted in sterile hard water. The mixture was maintained at 20^°C for 5 minutes after which an aliquot of solution was taken and the viral activity neutralised or suppressed. The effective viral activity was then determined under clean conditions. The pass criterion for the test is ≥ Log 4. The formulation under test showed effective virucidal activity with 0.5% w/v of test formulation at 5 minutes with results of Log 4.63.

Using BS EN 14348:2005 which is a quantitative suspension test for the evaluation of mycobactericidal activity of chemical disinfectants in the medical area including instrument disinfectants, the further efficacy of the formulation of the present invention was tested. A test suspension of Mycobacterium terrae (ATCC 15755) in a solution of interfering substances (Foetal Bovine Serum 0.6g/l) was added to a prepared sample of the 1 % w/v of the biocidal formulation to be tested diluted in sterile hard water. A test suspension of Mycobacterium avium (ATCC 15769) also in a solution of interfering substances (Foetal Bovine Serum 0.6g/l) was added to a prepared separate sample of the biocidal formulation to be tested diluted in sterile hard water. Each respective mixture was maintained at approximately 20^°C for 60 minutes after which an aliquot of solution was taken and the bactericidal action neutralised or suppressed. The effective mycobactericidal and tuberculocidal activity was then determined. The pass criteria for the test is > Log 4 and both the test for Mycobacterium terrae (ATCC 15755) and Mycobacterium avium (ATCC 15769) showed a log reduction of > Log 6. It should be noted that there are limitations to the minimum log reduction in respect of viruses. The log reduction value obtainable for viruses depends on the actual starting titre achievable for that virus. In standard tests, such as EN 14476, the virus strains are selected to be grown up to high titres (i.e. poliovirus 1 can be grown to > 1 x 10⁹ TCID₅₀ units and Adenovirus 5 can be grown to >1 x 10¹¹ TCID₅₀ units). However, many viruses cannot be grown to such high titres, thus not enabling a 4 Log reduction to be achieved. Assay sensitivity is also compromised by the requirement to neutralise residual disinfectant action by dilution of the virus/disinfectant suspension. Viral log reductions of 3 are set in some standards for this reason (e.g. this is acceptable to the US Environmental Protection Agency), and these are recorded as a minimum log reduction.

Accordingly, the formulation of the present invention provides a non corrosive and very effective alternative to those disinfectants currently on the market. Further, it neither bleaches, nor are there any hazardous gas emissions therefrom and it does not stain areas to which it is applied. It provides an unexpected discovery that the unique combination of ingredients provides a substantially more effective biocide than those currently in the art.

Claims

1. A water soluble biocidal formulation comprising iodide salt in an amount of 1-20% w/w, an amount of 25-95% w/w of peroxodisulphate as an oxidising agent; an amount of 1-30% w/w acetate salt; and an amount of diluents to make the concentration of the formulation up to 100% w/w.

2 A biocidal composition according to claim 1 wherein the iodide salt is present in an amount of 1 -10% w/w in the total formulation.

3. A biocidal composition according to claim 2 wherein the peroxodisulphate is present in an amount of 40-95% w/w in the total formulation.

4. A biocidal composition according to claim 3 wherein the acetate salt is present in an amount of 1 -20% w/w in the total formulation.

5. A biocidal composition according to any one of claims 1 to 4 wherein the diluents comprise one or more of surfactants, organic acids, buffering agents or sulphamic acid.

6. A biocidal composition according to claim 5 wherein the diluents are present in an amount of 5-10% w/w surfactant; 5-15% w/w of at least one organic acid; 10-30 % w/w buffering agent and 0-25% w/w of sulphamic acid.

7. A biocidal composition according to claim 6 wherein the buffering agent is present in an amount of 10-25 % w/w and the sulphamic acid is present in an amount of 0-10% w/w.

8. A biocidal composition according to claim 6 wherein the surfactant is present in an amount of 10% w/w, the buffering agent in an amount of 15-25 % w/w and the sulphamic acid in an amount of 0-5% w/w.

9. A biocidal composition according to any one of the preceding claims wherein the formulation buffers between pH 3 and 4.

10. A biocidal composition according to any one of the preceding claims wherein bromide salt is substituted for the iodide salt.

11. A biocidal composition according to claims 1-9 or 10 wherein the salts of iodide and bromide are selected from potassium or sodium.

12. A biocidal composition according to any one of the preceding claims wherein the salt is a potassium salt.

13. A biocidal composition according to any one of the preceding claims wherein the acetic salt is any salt or ester of acetic acid.

14. A biocidal composition according to claim 13 wherein the acetic salt or ester is sodium acetate.

15. A biocidal composition according to claim 5 wherein the surfactant is selected from a group of surfactants compatible with the organic acids and oxidising agent utilised in the formulation.

16. A biocidal composition according to claim 15 wherein the surfactant is an anionic surfactant.

17. A biocidal composition according to claim 16 wherein the surfactant is selected from the groups consisting of alkyl benzene sulphonates. alkyl sulphates, alkyl sulphonates, and alkyl ethoxysulphates.

18. A biocidal composition according to claim 17 wherein the surfactant is sodium dodecylbenzene sulphonate.

19. A biocidal composition according to claim 18 wherein the surfactant is 80% sodium dodecylbenzene sulphonate.

20. A biocidal composition according to claim 5 wherein the organic acids are one or both of succinic and malic acid.

21. A biocidal composition according to claim 5 wherein the buffering agent is a salt, ester or anion of phosphoric acid.

22. A biocidal composition according to claim 21 wherein the buffering agent is an alkali metal phosphate.

23. A biocidal composition according to claim 22 wherein the buffering agent is sodium hexametaphosphate.

24. A biocidal composition according to claim 21 wherein the buffering agent is an ammonium salt of phosphoric acid.

25. A biocidal composition according to claim 24 wherein the buffering agent is monoammonium phosphate.

26. A biocidal composition according to any one of claims 1 -4 wherein the peroxodisulphate oxidising agent is selected from any soluble peroxodisulphate.

27. A biocidal composition according to claim 26 wherein the peroxodisulphate is selected from the group of ammonium peroxodisulphate, potassium peroxodisulphate and sodium peroxodisulphate.

28. A biocidal composition according to claim 27 wherein the peroxodisulphate is sodium peroxodisulphate.

29. A water soluble biocidal formulation wherein said formulation comprises 4% w/w of potassium iodide, 50% w/w of sodium peroxodisulphate; 6% of sodium acetate; 10% w/w surfactant; 5-15% w/w of at least one organic acid; 15-25 % buffering agent and 0-5% sulphamic acid.

30. A dry composition comprising a water soluble biocidal formulation as claimed in any one of claims 1-29 to be made up in water at point of use.