34. Tests shall be carried out in duplicate using two 25 gram ± 1 gram portions of each sample submitted for testing. Each 25 gram ± 1gram sample shall be placed aseptically in a sterile container containing 225 ml ± 1 ml Buffered Peptone Water (BPW) (1) and incubated at 37°C ± 1°C for 18 to 24 hours.
Buffered Peptone Water – See Edel, W. and Kampelmacher, E. H. (1973) Bulletin of World Health Organisation, 167-174, World Health Organisation Distribution and Sales, CH-1211, Geneva 27, Switzerland (ISSN 0042-9686)