Buffered Peptone Water EP/USP

Pancreatic digest of casein provides nitrogen, vitamins, minerals and amino acids essential for growth. Potassium phosphates act as a buffer system and sodium chloride supplies essential electrolytes for transport and osmotic balance.

It is used in the preparation of the samples to dissolve or dilute water-soluble products (1:10 dilution) and non-fatty products insoluble in water (in general 1:10 dilution, but some may require larger volumes of Buffered Peptone Water). Fatty products are homogenized with a suitable sterile surface-active agent such as polysorbate or Tween 80, heated if necessary to no more than 40 °C or, in exceptional cases, to no more than 45 °C. They are mixed carefully and if necessary the temperature is maintained in a water bath. Enough of the pre-warmed Buffered Peptone Water diluent is added to make a 1:10 dilution of the original product.

Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.

Preparation

Suspend 16.1 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Dispense into appropriate containers and sterilize in autoclave at 121 °C for 15 minutes.

According to the European Pharmacopoeia

According to the European Pharmacopoeia for the examination of TAMC and TYMC in products:

Membrane filtration:

1. Prepare the product sample by suspending, dissolving or diluting the product to be examined in the Buffered Peptone Water.
2. Transfer the appropriate amount of the sample to a membrane filter.
3. Place the membrane on the surface of Trypticasein Soy Agar (LC-1068) in case of TAMC or Sabouraud Dextrose Agar (LC-1024) in case of TYMC.
4. Incubate the plate of Trypticasein Soy Agar (LC-1068) at 30-35 °C for 3-5 days and the plate of Sabouraud Dextrose Agar (LC-1024) at 20-25 °C for 5-7 days.

Plate-count methods:

1. Prepare the product sample by suspending, dissolving or diluting the product to be examined in the Buffered Peptone Water.
2. Inoculate the plates of Trypticasein Soy Agar (LC-1068) in case of TAMC or Sabouraud Dextrose Agar (LC-1024) in case of TYMC, conforming to the pour-plate method or the surface-spread method.
3. Incubate the plates of Trypticasein Soy Agar (LC-1068) at 30-35 °C for 3-5 days and the plates of Sabouraud Dextrose Agar (LC-1024) at 20-25 °C for 5-7 days.
4. Select the plates corresponding to a given dilution and showing the highest number of colonies less than 250 (TAMC) or 50 (TYMC).

Most-probable-number method (only for TAMC):

1. Prepare and dilute the product sample to be examined in Buffered Peptone Water, and inoculate into tubes of Trypticasein Soy Broth (LC-1224).
2. Incubate all tubes at 30-35 °C for 3-5 days.
3. Record for each level of dilution the number of tubes showing growth and determine the most probable number of microorganisms.

• European Pharmacopoeia 9.0