同时你看看PDA TR 29recovery for bioburden and endotoxin sampling:
recovery studies to determine percentage recovery from surfaces are not appropriate and are not normally done for microbiological sampling.
one reason for this is the question of enumeration in microbiological tests-"colony forming units" are typically counted as opposed to individual organisms.
a second reason for this is that vegetative organisms will die or lose viability when dried on a coupon in a standard sampling recovery procedure.
a third reason is that it is unclear which species should be used for a recovery study.
a fourth reason is that typically the limits set for bioburden are significantly below what could possibly cause either product quality issues or process performance issues.