Dear Sir. Concerning your issue about the validation of the non standard method in the context of medical laboratories. The laboratory shall validate examination procedures from non standard methods, laboratory designed or development methods, standard methods used outside their intended scope and modified validated methods. When examination procedures have been validated by the method developer (i.e., the manufacturer or author of a published procedure), the laboratory shall obtain information from the method developer to confirm that the performance characteristics of the method are appropriate for its intended use. When changes are made to a validated examination procedure, the influence of such changes shall be documented and, if appropriate, a new validation shall be carried out. Examination procedures from method developers that used without modification shall be subject to verification before being introduced into routine use. The verification shall confirm, through provision of objective evidence (performance characteristics), that the performance claims for the examination method have been met. The performance claims for the examination method confirmed during the verification process shall be those relevant to the intended use of the examination results. Verification and validation are two slightly different procedures. I think the following below links and the attached file may help you in your issue:

https://www.unodc.org/documents/scientific/validation_E.pdf

http://www.cfs.gov.hk/english/programme/programme_nifl/files/method_validation.pdf

http://apps.who.int/iris/bitstream/10665/258971/1/WHO-EMP-RHT-PQT-TGS4-2017.04-eng.pdf

http://www.who.int/diagnostics_laboratory/guidance/161222_tgs4_draft.pdf

Thanks

Thank you Isam Eldin for your detailed explanation and attachment of resources.