Combined Interpretations of the 2003, 2009, and 2016 Standards that apply to Volume 1 of the 2016 TNI Standard
Question:  For years we have been ordering  corrective action supplemental studies for PCB’s by asking for specific  aroclors (that were missed in the original PT sample) and have been allowed to  do so.  Recently our provider could not  fill an order and I went to a different provider.  They told me that I could not specify an  arochlor for a supplemental study.  When  I inquired about why I could not do so they told me that I should talk to  someone at the LDEQ and they would explain.   Before I called them I thought that there must be something in the  standard that I was over looking and I found the above citation.  I talked to several people at the LDEQ, they  were not aware of this citation and they seemed to be easy persuaded either  way. My interpretation of the standard is that we should have never been  allowed to specify aroclors for supplemental studies.  If this is true then I seem like a big  dilemma, because I have not been able to find a single person who already knew  about this and I have talked to a lot of people. We are trying to do the right  thing, but we are getting mixed signals and no one seem to be on the same  page.  There is a specific exception for  PCB’s, but it is vague and no one is interpreting it the same way.  What are we supposed to do? TNI Response:  The  PCB group is the exception. A laboratory does not need to specify the specific  Arochlor and should not specify a specific Arochlor because a component of  challenge of the PCB Group is both qualitative and quantitative detection. In  other words, the lab must report the correct quantitative value for a specific  Arochlor but also be able to report non- detects for the other Arochlors.  The 2016 standard has a significant rewrite  and specifically mentions aroclors and microbiology. However, the difference  between a supplemental PT needed for quantitative vs. qualitative failures was  not fully addressed for analyte groups. 
MODULE 1: PROFICIENCY TESTING REQUIREMENTS
Section: Volume 3 - 5.4.3

 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).
 Audit Sample Program is to develop consensus standards for the manufacture and analysis of audit samples for source emission testing.
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.