I got the USP Residual Solvents test method accredited. However, the auditor would like to see "validity of results" through proficiency testing, inter-laboratory or intra-laboratory comparison. No PT s are available. I don't have a secondary analyst, but I do have two instruments now although one is dedicated for QC and another for R&D. I can maybe run an intra-laboratory validation.
What are your thoughts? Any suggestions?