NaCl (reagent grade) 85.0 g Distilled water to make 1 liter
Stock solution 2 Sodium phosphate monobasic monohydrate NaH2PO4 H2O (monohydrate) (reagent grade)4* 227.6 g NaCl (reagent grade) 85.0 g Distilled water to make 1 liter
To obtain 0.02 M phosphate-buffered saline (0.85%), make 1:10 dilutions of each stock solution. For example:
Stock solution 1 50 ml Stock solution 2 10 ml Distilled water 450 ml Distilled water 90 ml Approximate pH, 8.2 Approximate pH, 5.6
Using pH meter, titer diluted solution 1 to pH 7.3-7.4 by adding about 65 ml of diluted solution 2. Use resulting 0.02 M phosphate saline buffer solution in the lysostaphin susceptibility test on S. aureus.
NOTE: Do not titer 0.2 M phosphate buffer to pH 7.3-7.4 and then dilute to 0.02 M strength. This results in a drop in pH of approximately 0.25. Addition of 0.85% salt after pH adjustment also results in a drop of approximately 0.2.
R43. Physiological Saline Solution 0.85% (Sterile) NaCl 8.5 g Distilled water 1 liter