A reference sample is a sample for the purpose of future analysis, which could refer to starting materials, packaging materials or finished products.
A retention sample is a sample representing the batch of finished product as distributed.
Samples from a stability trial program cannot be used as retention samples.
Multipack products and retention samples
Products packaged as complete multipacks do not necessarily need to be kept as retention samples. The requirement is that the amount of retention samples is sufficient to carry out analytical work during the entire shelf life of the product.