Proficiency testing sample acceptance limits and grading

Proficiency testing sample acceptance limits and grading. (1) Acceptance limits. A laboratory’s result for any analyte or analyte group is considered unacceptable if it meets any of the following conditions: (a) The result falls outside the acceptance limits. (b) The laboratory reports a result for an analyte not present in the PT sample. (c) The laboratory does not report a result for an analyte present in the PT sample. (d) The laboratory fails to submit its results to the PT sample provider on or before the deadline for the PT sample study. (e) The laboratory reports a method code for either an unapproved method or the method code reported is not appropriate for the technology-analyte or method-analyte combination. (f) The laboratory fails to meet department specified grading criteria for multi-analyte PT samples. (2) Grading. (a) PT samples for analytes in aqueous and non-aqueous matrices shall be graded in accordance with acceptance limits established by the department considering criteria developed by the EPA. (b) When the EPA has not developed acceptance limits for required PT sample analytes, the department may develop acceptance limits based on its experience or information supplied by approved PT sample providers. (c) When an insufficient number of laboratories participate in a study to generate peer-based acceptance limits in a PT sample with analytes for which the EPA has not established acceptance limits, the department may grade results using fixed acceptance limits. (d) PT sample analytes in drinking water shall be graded in accordance with the acceptance limits established in 40 CFR 141.23 (k) (3) (ii) , 40 CFR 141.24 (f) (17) (i) (C) and (D), 40 CFR 141.24 (f) (17) (ii) (B) , 40 CFR 141.24 (h) (19) (i) (A) and (B), and 40 CFR 141.89 (a) (1) (ii) , and 40 CFR 141.131 (b) (2) (ii) and (iii). (e) When accreditation in an analyte group is based on passing a representative PT sample containing more than one analyte, the laboratory shall report acceptable results on at least 80% of the analytes to achieve acceptable results for that sample. The department may investigate repeated failures for specific analytes and direct enforcement action in the event of two consecutive failures in the drinking water matrix or three consecutive failures in the aqueous matrix. (f) The department shall establish procedures for evaluating false positives and false negatives reported in analyzed PT samples.