Rinse samples (indirect method)
9.3 Rinse samples (indirect method)
Note: This method allows sampling of a large surface, of areas that are inaccessible or that cannot be routinely disassembled and provides an overall picture. Rinse samples may give sufficient evidence of adequate cleaning where accessibility of equipment parts can preclude direct surface sampling, and may be useful for checking for residues of cleaning agents, e.g. detergents.
9.3.1 Rinse samples should be used in combination with other sampling methods such as surface sampling.
9.3.2. There should be evidence that samples are accurately recovered.
For example, a recovery of > 80% is considered good, > 50% reasonable and < 50% questionable.