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Standard Interpretation

Standard: 2003 NELAC
Section: Appendix D.1.2.1
Link to relevant standard


The standard allows a lab to forgo the MDL determination if they do not report outside the calibration range unless the method requires it. Since the determination of the MDL and the LDR are pointless exercises for labs that do not report outside their calibration range, I believe that the MUR of 3/12/07 allows a lab to delete these requirements from method requirements since it does not change the chemistry, it does not change the determinative step, and it does not change the performance of the method. Agree? Disagree?


(Technical Assistance Committee / Quality Systems Committee / NELAP Board, 2-19-09)

Laboratories should attempt to reconcile all differences in the interpretation of the NELAC 2003 standards and/or analytical methods with the applicable EPA Program, Regional Office and/or NELAC accreditation body. The following is an opinion of the current TNI Technical Assistance Committee, Quality Systems Committee and NELAP Board.

The Quality Systems Committee and the Technical Assistance Committee feels that the MUR does not allow the lab to delete non-determinative steps from the method.

The MUR does not allow QC to be deleted. 136.6 (b)(i) stipulates that the requirements of paragraph (b)(2) be met for modified methods; (b)(2) states that QC acceptance criteria, both intial (start up) and ongoing must be equivalent to the approved method. This includes MDLs and linear range determinations where required.

Since the NELAC Standard requires an annual LOD check, this is acceptable in place of annual MDLs, UNLESS otherwise specified by the method or Program (i.e., SDWA methods require annual MDLs). However, if the LOD check does not pass, the the MDL study must be performed. (Note – this also does not remove methods requirements that MDLs must be performed anytime the method or instrument type changes.)

When required by method or regulation, the LDR must also be performed on initial method start-up. Conformance to the LDR can also be demonstrated if a lab does not report outside their calibration range, and analysis of the high standard is no more than 10% of the true value (LDR criteria). In this case, the lab has demonstrated that they continue to operate with their LDR.