develop consensus standards for use by TNI's programs. This group has a support role in assisting other programs with activities such as guidance and standards interpretation.
fosters the generation of data of known and documented quality is through the National Environmental Laboratory Accreditation Program, or NELAP. The purpose of this program is to establish and implement a program for the accreditation of environmental laboratories.
is to establish and maintain a national PT program to support TNI’s National Environmental Laboratory Accreditation Program, and other activities.
Field Activities Program (NEFAP) Executive Committee is to establish and implement an accreditation program for field sampling and measurement organizations (FSMOs).
on a variety of topics of interest to the environmental measurement community. TNI also hosts two regularly scheduled meetings per year, typically in January and August. Both are a week long and involve open meetings of TNI committees as well as training courses and other special sessions.Standard Interpretation
Standard: 2016
Section: V1M6, Section 1.7.2.4 (b)
REQUEST:
Section 1.7.2.4b in TNI Standard V1M6 is not clear in regard to whether samples with levels of activity (below three (3) times the MDA) are appropriate for use as MD as a measure of precision when the target analyte is not present.
According to Section 1.7.2.4b(i), "Duplicate analyses provide a measure of precision when the target analyte is present in the sample chosen for duplication." 1.7.2.4b(iv) states that "When samples have low levels of activity (less than approximately three (3) times the MDA) the laboratory, at its discretion, may analyze MS/MSD to determine reproducibility within a Preparation Batch in place of a MD."
The matrix of our Isotopic Gamma samples is NPW. We currently perform one MD per batch comparing activities for Ru-106, Cs-137 and Zn-65. Ru-106, Cs-137 and Zn-65 are typically undetected in our routine environmental samples. We don’t know whether Ru-106, Cs-137 and Zn-65 are absent or present at a low level.
1. Is it acceptable to use the MD as a measure of precision when the analyte is not known to be present?
TNI FINAL RESPONSE:
Yes, it is acceptable to use the MD as a measure of precision when the analyte is not known to be present, as long as acceptance criteria has been established and documented by the laboratory.