Phenols dilution

The hydroperoxyl radical formed, "00H, has a pKg of 4.75 and exists in water as a superoxide radical anion 02 Either species in water dismutates to produce O2 and hydrogen peroxide, H2O2, or, possibly, react with dissolved or adsorbed phenol. Dilute H2O2 does... 

Purify the DNA. We prefer extracting with hot phenol. Dilute the gel band with 400pi of 0.2 MNaCl-TE (10 mMTris, 1 mA/EDTA), pH 8.0. Add 500 pi of hot buffered phenol (pH 8.0).14 Place into a 65° water bath for 5 min. Vortex briefly to break up the agarose plug, then return the sample to the water bath for an additional 5 min. 

FIGURE 7. IR spectra in the OH stretching region of substituted phenols diluted in CCLt (--) and... 

The idea of the test is to compare other disinfectants with a standard. The disinfectant used as a standard is phenol which meets the requirements of the Eighth U. S. Pharmacopoeia, that is, the congealing point must not be below 40° C. A fresh 5% sol. of phenol is used as a source in making dilutions. In comparing other disinfectants with standard phenol dilutions the ability to kill BacilluB typhosus (Hopkins strain) is used as a basis of comparisons. 

O-H phenols, dilute phenol in CQ4 O-H from primary alcdiols as (—CH2—OH)... 

Procedures. The principle of all of the above tests is that serial dilutions of the test disinfectant and of the standard phenol (dilutions in arithmetic series for the Rideal-Walker, F.D.A, and A.O.A.C. tests and in logarithmic series for the Chick-Martin test) are inoculated with a given amount of the culture and at intervals one 4-mm loopful of the mixture is transferred to a tube of the culture medium which is incubated at 37° and the growths noted. By equating the end-point dilution of the disinfectant with that of phenol giving the same response, the phenol coefficient of the disinfectant is obtained. 

For the Rideal-Walker test, prepare four suitable serial dilutions of the disinfectant and one of the standard phenol in 5-ml amounts in 5 X f in. sterile test-tubes, and cool in a water-bath to 17-18°. At halfminute intervals, add 0-2 ml of the twenty-four-hour culture of Salm. typhi (also cooled to 17 18°) in turn to each of the tubes, and then at subsequent two and a half, five, seven and a half, and ten minute intervals remove one standard loopful of the mixture to a 5-ml tube of the medium, incubate at 37 for forty-eight to seventy-two hours and record the growths obtained. It may be necessary to repeat the test with another 5 dilutions, but using a different phenol dilution, in order to obtain a satisfactory end-point. Calculate the Rideal-Walker Coefficient by dividing the numerical value of the dilution of the disinfectant which... 

The A.O.A.C and F,D.A, methods follow a similar procedure to that of the Rideal-Walker method, except that the test is made at 20° (or 37°), 0-5 ml of the culture is added to each of the 5 ml disinfectant or phenol dilutions, the time intervals for subculturing are five, ten and fifteen minutes, and ten dilution tubes are required for each test, comprising eight of the disinfectant and the two of phenol. For ordinary coal tar disinfectants, the medium as given in the table (p. 206) is satisfactory, but V here they contain surface-active compounds of the quaternary ammonium type a Letheen medium is specified, which is the same basic medium with the addition of 0-07 per cent lecithin (Azolectin) and 0 5 per cent Tween 80. The Staph, aureus test is made at 20° on disinfectants intended for external use, and at 37 for those intended for personal use or for application to wounds. 

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