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Phosphate Buffer, pH 7.2

Phosphate Buffer, pH 7.2 is used for the preparation of microbiological dilution blanks in a laboratory setting. Phosphate Buffer, pH 7.2 is not intended for use in the diagnosis of disease or other conditions in humans.

The formula for phosphate buffer is specified by the American Public Health Association (APHA) for use in diluting test samples. Phosphate Buffer, pH 7.2 is specified for use in diluting water, dairy products and food for microbiological methods. In the examination of water and dairy products the addition of magnesium chloride is recommended.

This buffer is also referred to as Butterfield's Buffered Phosphate Diluent and recommended for examination of food. Phosphate Buffer, pH 7.2 stabilizes the pH of water used for dilutions.

 

Formula Liter
Potassium Dihydrogen Phosphate 26.22 g
Sodium Carbonate 7.78 g

*Final pH: 7.2 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.

Supplement

Magnesium Chloride, 5 mL

Directions

Stock Solution

  1. Dissolve 34 g of the medium in one liter of purified water.
  2. Mix thoroughly.
  3. Autoclave at 121°C for 15 minutes. Store under refrigeration.
  4. *Final pH is taken after Phosphate Buffer, pH 7.2 has been autoclaved and cooled to 25°C (room temperature).

Working Solution

  1. Add 1.25 mL of Stock Solution and 5 mL of a Magnesium Chloride solution (81.1 g MgCl2 ⦁ 6H2O per liter of purified water) to purified water and make up to one liter.
  2. Dispense into bottles or tubes to provide 99 ± 2.0 mL, 9 ± 0.2 mL or other appropriate quantities.
  3. Autoclave at 121°C for 15 minutes.
  4. *Final pH is taken after Phosphate Buffer, pH 7.2 has been autoclaved and cooled to 25°C (room temperature).

Order Details

Product # Product Description
7380A Phosphate Buffer, pH 7.2, 500 g
7380T Phosphate Buffer, pH 7.2, 5 kg