Iam developing a method for doing cleaning validation analysis for a product. Is it necessary to fix the specification (10ppm) with respect to sample concetration like usually we will do in Related substances.
thanks in advance.


Dear chrom,

if I get you right, there is a confusion between sample concentration and equipment contamination. The usual specification of 10 ppm (which, by the way, is the default specification and should be backed by a dosage calculation) refers to the concentration of the contamination in the contaminated batch, and not to a sample concentration. Thus, 10 ppm is equivalent to allow a 500 kg batch of product to be contaminated with a residue of 5000 mg of contaminant spread all over the equipment surface. The concentration of the contaminant in the sample depends on the sampled surface, the equipment surface, how much solvent you used to desorb the contaminant from the swab (or to rinse the sampled surface), and the further dilutions, but is over a wide range independent from the contamination in the equipment.

Best regards