Treatment of proficiency testing samples

Treatment of proficiency testing samples. (1) PT samples shall be subjected to any preparatory steps undergone by analytical samples of that matrix, unless the preparation instructions submitted by a PT sample provider specifically instruct omitting a preparatory step. (2) A laboratory may report multiple results for a single PT sample when the laboratory maintains accreditations for multiple technologies for any analyte or analyte group in aqueous and non-aqueous matrices. (3) A laboratory may report multiple results of a single PT sample when the laboratory maintains certifications for multiple methods for any analyte or analyte group in the drinking water matrix. (4) Prior to submitting PT sample results to a PT sample provider, all the following apply: (a) A laboratory may not send a PT sample, or portion of a PT sample, to another laboratory for analysis. (b) A laboratory may not knowingly analyze a PT sample, or a portion of a PT sample, from another laboratory. (c) Until a PT sample study has been closed, a laboratory may not share results of a PT sample from that study to any party other than the PT sample provider or regulatory agency.