However, upon evaluation of the nature of the contaminant and the effect on the analysis of each sample within the batch they determine there is no need or benefit to qualify sample results which were not above the reporting limit for the target analyte in question. For instance, a laboratory measures a concentration of a target analyte in the method blank at or above the reporting limit.
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Question: There is inconsistency as to whether a data qualifying code must be applied to a sample result for which no target analyte was quantitated at or above the reporting limit, yet for which the same target analyte concentration in the method blank was at or above the reporting limit. When it is not apparent which is more stringent, the QC in the mandated method or regulations is to be followed." 5.9.3 c) provides the following statements concerning the difference between 5035 and TNI: "The laboratory shall ensure that the essential standards outlined in Technical Modules or mandated methods or regulations (whichever are more stringent) are incorporated into their method manuals. Therefore, an appropriate blank for a solid matrix should not contribute contamination.
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TNI Response: A blank is required to be free of the analytes of interest. Also if one adds a solid matrix (even if it does not contain analytes of interest) to a VOA method blank, should not the same solid matrix be added to all the samples as well? Basically, is it necessary to add a solid matrix to a VOA method blank when analyzing low level soil samples? Is it the intent of NELAC's definition of a method blank to override what is presented in the method? Adding a solid matrix to a VOA method blank would only potentially add contamination and not be reflective of the cleanliness of the analytical system. Nothing about adding a solid matrix is mentioned. In fact, in method 5035 section 8.2 it is stated before processing samples to analyze an organic-free water method blank. No reference could be found in SW-846 Methods 5035, 8000, and/or 8260 that require a VOA method blank to contain a solid matrix. Question: The composition of a method blank shall consist of a quality system matrix that is similar to the associated samples and known to be free of analytes of interest. 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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