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: V1M4, Section 1.7.1.1 (f)
REQUEST:
The 2016 TNI Standard states that for regression or average response/calibration factor calibrations, the minimum number of non-zero calibration standards shall be specified as in the table included.
According to the manufacturer, the acceptance criterion for pH, Conductivity, and Fluoride and Ammonia calibrations utilizing ISE electrodes is based on the slope of the instrument. As known from pH measurement and calibration, the slope is an indicator of ISE performance. For ISE curves, there is both a linear section and a non-linear section.
Therefore, my question is, for ISE calibrations such as Ammonia and Fluoride, and other meter based tests such as Conductivity and pH, is the minimum number of calibration standards listed in the TNI table applicable?
File Submitted with SIR: ISE Calibrations.pdf
TNI FINAL RESPONSE:
Yes, they are applicable if the reference method describes a calibration procedure that includes average response/calibration factor or regression. Footnote b of V1M4 1.7.1.1.f states, "Fewer calibration standards may be used only if equipment firmware or software cannot accommodate the specified number of standards. Documentation detailing that limitation shall be maintained by the laboratory."