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TNI Standards Guidance

Disclaimer: This material represents the opinion of its authors. It is intended solely as guidance and does not include any mandatory requirements except where such requirements are referenced. This guidance does not establish expectations of being implemented universally, exclusively, in whole, or in part.

This guidance does not establish or affect legal rights or obligations and is not finally determinative of the issues it addresses. It does not create any rights enforceable by any party in litigation with TNI, its accreditation bodies, or affiliated institutions. Any decisions made by TNI regarding requirements addressed in this guidance will be made by applying the applicable standards, policies or procedures to the relevant facts.


Module: Quality Systems

Subject: Method Usage and Selection

Question 1

Does the laboratory have to use the most current edition or version of a method as suggested by TNI EL-V1M2 5.4.2, regardless of approval status?

Background:  There are many obsolete methods on the TNI method codes list. It has also been stated that we must use the most current version of Standard Methods.  Currently, some of the EPA program approved methods listed in 40 CFR Part 136.3 and Part 141 go back to the 15th edition of Standard Methods and may not include the most recent methods.  In addition, some of the accrediting agencies will still accredit the older methods.  It is confusing when trying to determine what method to use.


There are conditions when it is appropriate or necessary for laboratories to use methods that are no longer EPA-approved or that are deemed obsolete by the U.S. EPA (e.g. permits or QAPPs issued by regulatory agencies).  In conformance to the 2003 NELAC Standard, applies, but the 2009 Standard does not specifically address this circumstance.  Because not all regulatory programs requiring accreditation use the most recent revision of a method, TNI must continue to maintain method codes for current and historical versions of methods.

Laboratories are responsible for using the method that meets the client’s needs. (Laboratories must use the current and approved revision when not specified by a client or an older revision when mandated by regulation or project QAPP.)  All previous method versions are not deemed obsolete when newer versions of the reference methods, consensus standards, or guidance methods have been released.  If a newer version of a method is made available it does not mean that is has been approved or that previous version(s) are not accepted or even required by the regulating community.  During the review of requests, tenders, and contracts (V1M2, section 4.4.1), the laboratory must ensure that it reviews the requirements and applicable permits, rules and regulatory requirements (e.g. EPA, States, data user) before work commences. Federal mandates may require approved test procedures as listed in the applicable parts of Code of Federal Regulations (e.g. 40 CFR 141) and in subsequent Federal Register Updates (e.g. Method Update Rule).


NELAC 2003

Sources of Methods states that “The laboratory shall ensure that it uses the latest valid edition of a standard unless it is not appropriate or possible to do so.” NELAC states that “When the use of specific methods for a sample analysis are mandated or requested, only those methods shall be used.” is modified by the statement “….unless it is not appropriate or possible to do so.”

TNI EL-V1M2 2009  5.4.2

Selection of Methods (ISO/IEC 17025:2005(E), Clause 5.4.2)
…. The laboratory shall ensure that it uses the latest valid edition of a standard unless it is not appropriate or possible to do so.