Disinfectants determination

The ideal recommended cyanuric acid concentration is 30—50 ppm (Table 2). Although this range can be readily maintained when using hypochlorite sanitizers, it cannot be maintained when using chloroisocyanurates since they increase the cyanuric acid concentration. The NSPI recommends a maximum of 150 ppm cyanuric acid. Many health departments limit cyanuric acid to 100 ppm. No significant increase in stabilization occurs beyond 50—100 ppm, and since high levels of cyanuric acid slow down the rate of disinfection, the pool water should be partially drained and replaced with fresh water to reduce the cyanuric acid to below recommended maximum levels. Cyanuric acid is determined turbidimetricaHy after precipitation as melamine cyanurate. 

Although pH determines the ratio of hypohalous acid to hypohaUte ion, the fraction of the total available halogen present as HOX is dependent on of the halamine as well as the concentration of excess amine. In the case of chloroisocyanurates, which are the most widely used /V-ch1oramine disinfectants in swimming pools and spas, the extent of hydrolysis at 1 ppm av CI2 (as monochloroisocyanurate) is - 34% but only - 1% when 25 ppm cyanuric acid is added (4). Nevertheless, effective disinfection can stiU occur with chloroisocyanurates if a sufficient FAC is maintained, eg, 1—3 ppm. The observed reduction in disinfection rate because of cyanuric acid (6) has been shown to be direcdy related to the concentration of HOCl formed by hydrolysis of chloroisocyanurates (10). 

The strength of a hydrophilic lens material determines how well the material survives the patient s handling, cleaning, and disinfection regimen. Materials with higher Dk have been found to be generally more fragile (31). 

Tests have been developed that test different products for their effectiveness as a healthcare personnel handwash (327) evaluate hand disinfectants for use in surgery (333) determine the effectiveness of a surgical hand scmb, ie, the glove juice test (311,329) evaluate antiseptics for the oral cavity to be used in mouthwashes (334,335) and test antiseptics for the periurethral area and appHcation to catheters (336,337). A method used for a test comparing four antiseptic products was adopted as recommended practice by the Association of Practitioners of Infection Control (338). 

Tests have been published for determining toxicity towards leucocytes. Evaluation on the infected chorioallantoic membrane of hens eggs was suggested as being a useful method of testing potential wound disinfectants. 

For assaying herpes virus, monolayers of baby hamster kidney (BHK) cells are used. Virus titre is expressed as the number of plaque-forming units (pfu) per millilitre before and after exposure to a disinfectant, so that the virucidal efficacy of the test agent can be determined. A diagrammatic representation is given in Fig. 11.7. 

The human immunodeficiency virus (HIV lymphadenopathy-associated virus, LAV human T-cell lymphotrophic virus type 3, HTLV III) is responsible for acquired immune deficiency syndrome (AIDS see Chapter 3). Because of the hazard and difficulties of growing the virus outside humans, a different approach has to be examined for determining viral sensitivity to disinfectants. 

Studies have demonstrated that one such method is to examine the effects of disinfectants on endogenous RNA-dependent DNA polymerase (i.e. reverse transcriptase) activity. In essence, HIV is an RNA virus after it enters a cell the RNA is converted to DNA under the influence of reverse transcriptase. The virus induces a cytopathic effect on T lymphocytes, and in the assay reverse transcriptase activity is determined after exposure to different concentrations of various disinfectants. However, it has been suggested that monitoring residual viral reverse transcriptase activity is not a satisfactory alternative to tests whereby infectious HIV can be detected in systems employing fresh human peripheral blood mononuclear cells. 

Disinfectant and sanitary powders are the subjeet of a British Standard (BS 1013 1946), now withdrawn, whieh describes a method of determining the RW coeffieient of such powders. A weighed quantity was shaken with distilled water at 18°C for 30 minutes and this suspension was used in the test already deseribed (seetion 3.1.1). 

Heretofore the milieu on or in whieh the disinfectant has been required to act has been either solid or liquid now antibacterial aetion in the gas or vapour phase or in the form of aerosol (colloidal) interaction must be considered, and this presents the problem of determining the viable airborne population. 

Method for determination of the antimicrobial activity ofQAC disinfectant formulations. BS 6471 1984 [1994]. 

Methodfior determination of the Rideal-Walker coefficient of disinfectants. BS 541 1985 [1991]. 

As already mentioned, smooth, polished surfaces are cleaned most easily. Floors and horizontal surfaces should be cleaned and disinfected daily, walls and ceilings as often as required, but the interval should not exceed 1 month. Regular microbiological monitoring should be carried out to determine the efficacy of disinfection procedures. Records should be kept and immediate remedial action taken should normal levels for that area be exceeded. 

The first draft (finished in 1993 and revised in 1995) describes a test method for determination of the bactericidal activity of a chemical disinfectant applied to a contaminated surface under laboratory conditions ... 

Stainless steel disks are contaminated with a bacterial test suspension and dried. The disinfectant is applied on the dried film on the disk and kept at a specified temperature for a defined time. The disk is than transferred to a previously validated neutralization medium to stop the action of the disinfectant. The cfii of surviving bacteria recovered from the surface is determined quantitatively. 

In a parallel test with water instead of disinfectant the colony forming units (cfu) of surviving bacteria are determined and the reduction in viable counts is calculated. 

In one procedure that has been widely used, the sample, after suitable treatment, is refluxed with sodium and isopropyl alcohol, after which the solution is diluted with water and the inorganic chloride is determined by standard methods (13, 54) The method has been adopted by the Association of Official Agricultural Chemists 29, 30) as a tentative one for technical DDT and for dusts, oil solutions, and aqueous emulsions of DDT, for use in the absence of other chlorine-containing compounds. The National Association of Insecticide and Disinfectant Manufacturers has also accepted the total-chlorine method for the analysis of these preparations 28). Essentially the same procedures have been described by Donovan 22), of the Insecticide Division of the Production and Marketing Administration, for technical DDT and various commercial DDT products containing no other compounds interfering with the chlorine determination. 

The use of AAAs as feed supplements appears an attractive approach either in itself or in combination with pro-, pre- and synbiotics, but the lack of animal feeding studies in which the efficacy of this approach could be determined makes it difficult to assess to what extent a two-barrier (targeting control at both the stomach and intestinal level) approach is commercially feasible. Also, since the viability of probiotics may also be affected by the use of AAA to increase the disinfection activity of the stomach, probiotics may need to be formulated in a way that protects them during stomach transfer. However, its potential should be determined in future research. 

The authors describe experiments on six NR compounds commonly used for latex gloves to determine the potential hazards of skin contact with reference to curing compounds and accelerators, including mercaptobenzthiazole and zinc dialkyldithiocarbamates. Simulation methods and the influence of a common hand disinfectant were investigated. In the case of tetramethylthiuram disulphide, it was discovered that decomposition products could be formed on the skin which are not present in the original rubber. 6 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. Accession no.849747... 

For the past 50 years the determination of the sanitary quality of water has been based on the enumeration of indicator micro-organisms (e.g. coliform bacteria). The adequacy of coliform enumeration methods for this purpose has been questioned [21]. The current trend of year-round disinfection of waste water effluents and the increasing discharge of both toxic substances and heat from industrial outfalls cast further doubt on the accuracy of biological indicator systems [22]. 

Likewise, the behavior of a print in connection with sausage, ham, bacon, or fish, or its sensitivity to cleaning agents, disinfectants, bath soaps, essential oils, or fertilizers may be determined accordingly. 

The fate of dissolved amines during disinfection of water by chlorination was determined by membrane injection MS. Aliphatic amines undergo TV-chlorination to exhaustion of the N-H atoms by one of the tentatively proposed paths shown in reaction 28. Aromatic amines undergo mainly ring substitution however, the possible intervention of N-C1 intermediates is not excluded. At pH 10.6 aniline chlorination is much slower than that of n-butylamine383. 

Determination of Inorganic Oxyhalide Disinfection By-products in Drinking Water using Ion Chromatography with the Addition of a Postcolumn Reagent for Trace Bromate Analysis... 

---