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July 1, 2007 marks the implementation date for the new NELAC Fields of Proficiency Testing (FoPT) tables. This implementation is highly important to APG and its customers because the tables govern how acceptability limits are calculated for NELAC regulated analytes. APG has spent months planing for the changes and ensuring an understanding of what is necessary to meet customers' reporting requirements. Although the PT Provider handles the majority of work for a new FoPT release, it is helpful for laboratories to also understand the revisions.
The first point is the 2007 FoPT release is not accompanied by a revision of the NELAC rules. This means the 2003 NELAC Standard document, which includes the 1998 EPA Criteria Document by reference, is still required for full compliance and laboratory accreditation. The new FoPT tables and the 2003 Standard are available at The NELAC Institute website (http://www.nelac-institute.org/).
NELAC, now formally referred to as TNI, chose to release the new FoPT without highlighting changes. Previous FoPT releases did include helpful highlights and notes on changes. Many key items are reviewed here, although this article will not be able to detail everything. There are minor changes, such as exclusions for Microbiology analytes in several of the Drinking Water (DW) and Non-potable Water (NPW) footnotes. However, most of the 2007 revision is not related to the DW and NPW tables.
The major portion of FoPT revision applies to Soils analysis. The 2002 Resource Conservation and Recovery Act (RCRA) table is replaced by the Solid and Chemical Materials (SCM) table. This signifies the formalization of Soils analysis within the FoPT schedules. APG recommends all laboratories closely review the 2007 SCM table. One noteworthy shift is the decision to change PCBs in Oil from a two sample evaluation to a single sample. Also, Aroclor 1016 and Aroclor 1242 are listed as separate analytes in PCBs in Oil.
There are numerous changes in analyte concentration ranges designed to improve the performance of SCM PT products, with the most significant being a change of units in the PCB (Solids) sample from ug/kg to mg/kg. Study of Proficiency Testing Reporting Limit (PTRL) revisions in the SCM table will be crucial to laboratories for confidence analysis methods are properly developed to meet reporting requirements. New analytes are also listed, such as Ignitability, Corrosivity, n-Hexane Extractable Material and non-Polar Extractable Material.
The remaining differences in the 2007 SCM applies to PT Provider assessment of data results reported by laboratories. The 2002 table listed all analytes for assessment by Study Mean with three interlaboratory standard deviations allowed for an acceptable certification. Various analytes, particularly Metals and Volatiles, are assigned ABCD regression constants which are applied to determine acceptability. Most remaining analytes have at least a CD regression, indicating the Study Mean determines the acceptability midpoint, but the allowable variation is regulated by the table.
Finally, the footnotes to the 2007 SCM table are extensive in comparison to the previous draft releases. One common issue in Soils analysis is deciding whether to report zero or “<” values when low results are obtained from a PT sample. SCM footnote number four details rules for the calculation of acceptability limits that provide guidance to the laboratories on this point. Results above the PTRL listed for any analyte should be reported in all cases. This also indicates analysis methods should be able to quantitate data down to the PTRL, at least, and it is advisable to employ methods that produce valid data at levels below the listed PTRLs. With this design, laboratories can confidently report data as “< 5” (if the PTRL is 5) when appropriate. APG will include the PTRLs in sample documentation for all studies beginning with July 2007.
APG is ready for the FoPT implementation and provides a staff of Relationship Specialists and Technical Support Chemists to answer any questions or concerns that may arise. The APG staff is available from 8am to 5pm EST and you can contact APG by calling 1-800-272-4442 or emailing info@apgqa.com.
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