(1) The laboratory must participate in an approved proficiency testing (PT) program on an ongoing basis and achieve a passing score for each field of testing parameter for which the lab will be or is accredited.

(2) The cost of obtaining and testing PT samples is the sole responsibility of the laboratory.

(3) The department will maintain a list of approved proficiency tests and proficiency test providers that laboratories can use.

(4) A laboratory must successfully complete a minimum of one round of PT for each field of testing the lab seeks to be accredited for and provide proof of the successful PT results to the accrediting authority prior to initial accreditation.

(5) Accredited laboratories must successfully analyze a minimum of two PT samples for each parameter per year.

(6) The closing dates of a PT study for a particular field of accreditation can be no more than seven months apart, and the opening date of a PT study for a particular parameter must be at least seven calendar days after the closing date of the previous PT study for the same parameter or field of testing.

(7) At least one of the scores must be from a round of PT that occurs within six months prior to the laboratory's accreditation renewal date.

(8) To maintain accreditation, the laboratory must continue to pass each PT and parameter for which the lab is accredited.

(9) If the laboratory fails to achieve a pass for a parameter, the laboratory must investigate the root cause of the laboratory's performance and establish a corrective action plan for each unsatisfactory analytical result within five business days and report its finding and resolution to the department.

(10) If the corrective action has not resolved the analytical deficiency, the laboratory must suspend testing of that parameter, even if they have not yet been contacted by the department to do so first. The laboratory must then work with the department to resolve the issue and must receive authorization from the department before they can restart testing for that parameter.

(11) The department may require the laboratory to submit raw data along with the report of analysis of PT samples.

(12) If the PT provider does not provide individual acceptance criteria for each analyte, the following criteria will be applied to determine whether the lab achieves a passing score for the round of PT:

(a) +/- 30 percent recovery from the reference value for residual solvent testing; or

(b) +/- 3 z or 3 standard deviations from the reference value for all other fields of testing.

(13) The department may waive proficiency tests for certain parameters if approved PT samples are not readily available or for other valid reasons.

(a) If a proficiency test is not available for any parameter for which the laboratory is accredited or applying for accreditation, the laboratory must implement an alternative assessment procedure for the affected analyte(s) approved by the department.

(b) An alternative assessment requirement can be fulfilled via a split-sample analysis sent to testing staff as a blind or potential customer sample unknown to the analyst.

(14)(a) PTs must undergo the identical preparation and analytical processes that are used for customer samples including, but not limited to, adhering to the same sample tracking, sample preparation, analysis methods, standard operating procedures, calibrations, quality control, and acceptance criteria used in testing customer samples.

(b) Should a PT provider require a sample preparation step such as spiking a standard onto a matrix or hydrating a sample, the laboratory must prepare the sample according to their instructions. Testing a spiking solution independently is not allowed.

(15) The laboratory is responsible for ensuring the department receives all PT results directly from the PT provider.

(16) The laboratory must ensure that the information provided to the PT provider reflects accurate information about the laboratory that corresponds to the information in the laboratory's accreditation or application for accreditation including, but not limited to:

(a) The laboratory's name and address;

(b) The laboratory's ID number; and

(c) The method and analyte codes.

(17) For pesticide and cannabinoid concentration analyses, a laboratory must use PT samples made with a useable cannabis matrix.

(a) If a useable cannabis matrix is unavailable, then a PT sample made with useable hemp matrix may be used.

(b) If a PT sample made with a useable hemp matrix is used for accreditation of cannabinoid concentration analysis, then the PT vendor must prepare the sample in useable hemp material itself and may not provide a separate spiking solution with the sample.

(18) Presence-absence microbiology parameters must correctly detect the presence or absence of target organisms on all replicates in their PTs to be considered acceptable.

(19) It is strictly prohibited for laboratories to communicate with other laboratories about proficiency testing samples prior to the final results reported back to the laboratory by the proficiency testing provider.

(20) It is strictly prohibited for laboratories to send PT samples to another laboratory for testing.

(21) Laboratories must participate in interlaboratory comparison testing when the department provides samples.

(a) Testing and reporting of interlaboratory comparison sample results to the department must be conducted within five business days of receipt of samples.

(b) The cost of performing interlaboratory comparison testing is the sole responsibility of the laboratory.

(c) To be considered acceptable, results from interlaboratory comparison testing must be within:

(i) +/- 30 percent recovery from the reference value for residual solvent testing; or

(ii) +/- 3 z or 3 standard deviations from the reference value for all other fields of testing.

(d) If a laboratory fails an interlaboratory comparison test, they must investigate the root cause of the laboratory's performance and establish a corrective action plan for each unsatisfactory analytical result within five business days and report its finding and resolution to the department.

(e) Failure to correct deficiencies or findings of misconduct identified from interlaboratory comparison testing could lead to suspension of accreditation.

(f) Laboratories will not be required to perform interlaboratory comparison testing on more than five samples per year per parameter being investigated.