![]() 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. Question: The standard allows a lab to forgo the MDL determination if they do not report outside the calibration range unless the method requires it. TNI Response: This clause was deleted in the 2009 standard. The question is, is this something that NELAC supports? I would like to see some clarification on this standard, because the way it is written, it seems to create the perception that we are missing something. ![]() Our clients would be very appreciative of invariable LODs. Is the standard giving me permission to adjust MDLs upward, provided that they are supported by MDL studies, so that the LOD is within a fixed factor of the LOQ? This would be convenient, because the LOD would not change from year to year. In my 20+ years in environmental laboratories, I have seen LOQ/LOD ratios that are all over the place. In our laboratory, metals by ICP-MS have ratios of LOQ/LOD that range from 1.4 to 100. However, auditors are implying that there should be a fixed factor (or range, such as 1-10) separating the LOD and the LOQ. In this context, the LOD and the LOQ are numbers that are derived independently, and the only requirement is that the LOD be equal to or less than the LOQ. Typically the low point of the calibration curve is equal to the LOQ when adjusted for sample preparation factors. The LOQ is interpreted by our company to be lowest concentration that can be reliably and accurately reported, and it is required that it be encompassed in the calibration curve. The MDL is derived from an MDL study following the guidance in 40CFR136. ![]() The LOD (which is not clearly defined in the NELAC standard) is interpreted by our company to be equivalent to the MDL. Question: Our laboratory was recently cited with "The laboratory has not established procedures to relate LOD's with Limits of Quantitation (LOQ's) (EPA 200.8, 300.0, 6020, 9056)." I must be missing something here, or perhaps an expectation is being created by this standard, which is a favorite deficiency for auditors. Section: 1.5.2 Limit of Detection and Limit of Quantitation MODULE 4: CHEMISTRY TECHNICAL REQUIREMENTS Combined Interpretations of the 2003, 2009, and 2016 Standards that apply to Volume 1 of the 2016 TNI Standard
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