Oxoid
Phosphate Buffered Saline Tablets (Dulbecco A) is used for preparation of
balanced salt solution without calcium and magnesium.
PHOSPHATE BUFFERED SALINE
Code: BR0014
(Dulbecco `A’ Tablets)
|
Formula |
gm/litre |
|
Sodium chloride |
8.0 |
|
Potassium chloride |
0.2 |
|
Disodium hydrogen phosphate |
1.15 |
|
Potassium dihydrogen phosphate |
0.2 |
|
pH 7.3 |
|
Directions
Dissolve 10 tablets in 1 litre of distilled water and autoclave for 10 minutes at 115°C. The solution will be quite free from insoluble matter.
Description
This balanced salt solution is issued to meet the requirements of those tissue culture workers who use the Dulbecco Solution with and without calcium and magnesium. Oxoid Dulbecco `A’ Solution corresponds to the original formulation of Dulbecco and Vogt1 except that calcium and magnesium are omitted and may be added separately.
An example of the use of Solution `A’ is in the suspension of cells from a monolayer culture2. Cells growing in monolayer on a glass surface may be brought into suspension by a number of methods, including the application of chelating agents such as Versene (diamino-ethane-tetra-acetic acid) or its salts. Chelating agents bind divalent cations, such as calcium and magnesium ions, and it is probably this effect which causes the cells to become detached from the glass. Dulbecco `A’ Solution is therefore used to rinse the sheet of cells free from growth medium before application of the chelating agent - this latter solution may consist of Dulbecco `A’ Solution containing 0.02% w/v of sodium versenate and 0.02% w/v of glucose.
Quality control testing of Phosphate Buffed Saline BR0014 includes teting as a diluent in accordance with ISO 11133:20143
Molarity
The molarity of a solution of phosphate-buffered saline is expressed as the number of moles of solute in 1 litre and is associated with each species in a mixture.
Molarity figures given are for the individual components of the formula.
|
Sodium chloride |
0.137 mol |
|
Potassium chloride |
0.003 mol |
|
Disodium hydrogen phosphate |
0.008 mol |
|
Potassium dihydrogen phosphate |
0.0015 mol |
Quality Control
A satisfactory result is represented by recovery of ± 30% of the control number of colony forming units (CFU) taken at time 0 from an inoculum of 50 cfu to 150 cfu after holding at 20 °C to 25 °C for 45 minutes to 60 minutes.
|
Postive Controls: |
Expected results |
|
Escherichia coli ATCC® 25922*
WDCM00013 |
White/grey colonies on the control medium - Tryptone Soya Agar |
|
Staphylococcus aureus® ATCC 25923*
WDCM00034 |
White/grey colonies on the control medium -Tryptone Soya Agar |
|
Negative Control: |
|
|
Uninoculated medium |
No change |
*organism available as a Culti-Loop™
References
1. Dulbecco and Vogt (1954) J. Exp. Med. 99. 167-182.
2. Paul J. (1965) `Cell and Tissue Culture’ 3rd ed, Livingstone Ltd., London.
3. International Organization for Standardization. ISO 11133:2014 Microbiology of food, animal feed and water - Preparation, production, storage and performance testing of culture media
