Disinfection samples

Contains additives used to neutralize residuals of halogen-based disinfectants, such as sodium hypochlorite (bleach). Contains additives used to neutralize residuals of halogen and quaternary ammonium chloride-based disinfectants. Samples collected using sterile swabs and buffer solution must be transferred to media for culturing and enumeration. (Courtesy of Northview Biosciences, Inc., Northbrook, IL.)... 

Available Chlorine Test. The chlorine germicidal equivalent concentration test is a practical-type test. It is called a capacity test. Under practical conditions of use, a container of disinfectant might receive many soiled, contaminated instniments or other items to be disinfected. Eventually, the capacity of the disinfectant to serve its function would be overloaded due to reaction with the accumulated organic matter and organisms. The chlorine germicidal equivalent concentration test compares the load of a culture of bacteria that a concentration of a disinfectant will absorb and still kill bacteria, as compared to standard concentrations of sodium hypochlorite tested similarly. In the test, 10 successive additions of the test culture are added to each of 3 concentrations of the hypochlorite. One min after each addition a sample is transferred to the subculture medium and the next addition is made 1.5 min after the previous one. The disinfectant is then evaluated in a manner similar to the phenol coefficient test. For equivalence, the disinfectant must yield the same number of negative tubes as one of the chlorine standards. 

Tests should also be done in the presenee of organic matter (e.g. albumin) and in hard water. It is important to remember when performing viable counts that care must be taken to ensure that, at the moment of sampling, the disinfection process is immediately arrested by the use of a suitable neutralizer or ensuring inactivation by dilution (Table 11.4). Membrane filtration is an alternative procedure, the principle of whieh is that treated cells are retained on the filter whilst the disinfectant forms the filtrate. After washing in situ, the membrane is transferred to the surface of a solid (agar) reeoveiy medium and the eolonies that develop on the membrane are counted. 

The principle of tests evaluating the efficacy of surgical hand disinfectants is to sample the resident flora of the hands before and after surgical hand disinfection. 

The DBPCAN database contains predicted estimates of carcinogenic potential for 209 chemicals detected in finished drinking water samples having undergone water disinfection treatment. 

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. 

Testing separately samples using both methods at 100°C learns that that the velocity of the processes increases considerably and the time for treatment is shortened but the values of physicomechanical properties are reduced with 8-9%. That is a reason to consider that optimal conditions for treatment using both methods are 80°C during 50 minutes. These conditions could be created and maintained in means for decontamination and disinfection of devices and armament. 

Experiments to identify disinfection by-products (DBFs) have been carried out using two different procedures. In the first, natural waters (e.g., river, lake) are reacted with the disinfectant, either in a pilot plant, an actual treatment plant, or in a controlled laboratory smdy. fii the second type of procedure, aquatic humic material is isolated and reacted with the disinfectant in purified water in a controlled laboratory study. This latter type of study is relevant because humic material is an important precursor of THMs and other DBFs. Aquatic humic material is present in nearly all natural waters, and isolated humic material reacts with disinfectants to produce most of the same DBFs found from natural waters. Because DBFs are typically formed at low levels (ng/L-pg/L), samples are usually concentrated to allow for DBF detection. Concentration methods that are commonly used include solid phase extraction (SFE), solid phase microextraction (SFME), liquid-liquid extraction, and XAD resin extraction (for larger quantities of water) [9]. 

Vincenti M, Biazzi S, Ghiglione N, Valsania MC, Richardson SD (2005) Comparison of highly-fluorinated chloroformates as direct aqueous sample derivatizing agents for hydrophilic analytes and drinking-water disinfection by-products. J Am Soc Mass Spectrom 16(6) 803-813... 

Chlorotrifluoromethyl aniline (no. 73.) was found in the sediment samples. This compound is used as a reactant with chloro-aniline (no. 72) in the preparation of 4,4 -dichloro-3-(trifluoromethyl)-carbanilide, a disinfectant. Two other related compounds also found in some of the sediments were chlorophenyl isocyanate (no. 74) and chloro(-trifluoromethyl)phenyl isocyanate (no. 75). This suggests that some of the 4,4 -dichloro-3-(trifluoromethyl)-carbanilide may, in fact, exist in the sediment extracts but is decomposed in the injection port of the gas chromatograph, since it is very doubtful that the easily hydrolyzable isocyanates exist as such in the sediments. To strengthen this hypothesis some 3,4,4 -trichlorocarbanilide [none of the 4,4 -dichloro-3-(trifluorome-thyl)-carbanilide was available] was analyzed by GCMS. The injection port temperature was 300°C. As expected, none of the parent compound eluted from the column. However, mass spectra were obtained for chlorophenyl isocyanate, dichlorophenyl isocyanate, chloroaniline, and dichloroaniline. The presence of the carbanilides themselves (no. 76, 77, 78) was confirmed with the help of HPLC and mass spectral identification. 

Chlorate and chlorite ions are disinfection by-products (DBPs) from water treatment using chlorine dioxide. Table 6-2 contains data from four water treatment facilities in the United States that use chlorine dioxide as a disinfectant. Source water samples were also analyzed from each facility and no chlorite or chlorate ions were detected. In all water treatment plants, water taken from the distribution system (i.e., water sampled at water treatment plant) had measurable concentrations of both chlorite and chlorate ions. The ranges of concentrations were 15-740 and 21-330 pg/L for chlorite and chlorate, respectively (Bolyard et al. 1993). 

Alder P., T. Steger-Hartmann, and W. Kalbfus (2001). Disinfection of natural and synthetic estrogen estrogenic steroid hormones in water samples from Southern and Middle Germany. Acta Hydrochimica et Hydrobiologica 29 227-241. 

RODAC dish (Falcon) code No. 1034, containing a culture medium made to the formula as indicated in the USP should be used. This medium contains approximately 0.7 g/1 lecithin and 5.0 g/1 polysorbate 80, two commonly used neutralizers, to inactivate residual disinfectants on the spot where the sample is collected. 

Disinfect the sampling point from inside and its surrounding with 70% ethyl alcohol or 3% H2O2 for 2 minutes. 

Open the sampling point to maximum — about 30 seconds with pulse flushing (quick open and close) — to purge any dust and residual of the disinfectant. 

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