PDFWAC 173-50-070
Proficiency testing (PT).
(1) The lab accreditation unit advises applying laboratories of specific requirements for participation in proficiency testing (PT) studies for applicable parameters. Proficiency tests conducted under the provisions of other recognized programs may be used to satisfy these requirements. The lab accreditation unit determines the sufficiency of such proficiency tests.
(2) Accredited laboratories must analyze a minimum of two PT samples per applicable parameters per year. After an accredited laboratory submits two satisfactory PT sample results and no unsatisfactory results in an accreditation year, the laboratory is required to submit only one satisfactory PT sample result in subsequent accreditation years. This applies as long as there are no intervening unsatisfactory PT sample results. For bioassay parameters, only one acceptable PT sample is required per parameter per year.
(3) The lab accreditation unit may require the laboratory to submit raw data along with the report of analysis of PT samples.
(4) The lab accreditation unit may waive proficiency tests for certain parameters if PT samples are not readily available or for other valid reasons.
(5) Applying laboratories are responsible for obtaining PT samples from vendors approved by the lab accreditation unit. No fee shall be charged to the department for the purchase or analysis of PT samples.
(6) PTs must undergo the identical preparation and analytical processes that are used for samples.
(7) When two or more approved PT providers make available a PT sample for a parameter in an appropriate matrix, the laboratory must analyze and pass a PT to gain or maintain accreditation, unless an exception is approved by the department.
(8) Presence-absence microbiology parameters must pass all 10 replicates in their PTs to be considered acceptable.
[Statutory Authority: RCW 43.21A.230. WSR 23-18-059 (Order 22-07), § 173-50-070, filed 9/1/23, effective 10/2/23. Statutory Authority: RCW 43.21A.230, 43.20.050 and 2009 c 564 § 301. WSR 10-17-032 (Order 09-09), § 173-50-070, filed 8/9/10, effective 9/9/10. Statutory Authority: RCW 43.21A.230. WSR 02-20-090 (Order 01-12), § 173-50-070, filed 10/1/02, effective 11/1/02; WSR 93-20-011 (Order 92-53), § 173-50-070, filed 9/22/93, effective 10/23/93; WSR 90-21-090 (Order 90-21), § 173-50-070, filed 10/19/90, effective 11/19/90; WSR 89-10-001 and 90-07-017 (Order 89-1 and 89-1A), § 173-50-070, filed 4/20/89 and 3/13/90, effective 4/13/90.]