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Standard Interpretation



SIR #: 398
Standard: 2016
Section: V1M4, Section 1.7.1.1


REQUEST:

Section 1.7.1.1(f) refers to the minimum number of calibration standards required for each calibration type. Section 1.7.1.1(l) provides an exception for test procedures/methods that specify the allowance of a single calibration standard and zero point within the linear range.

Do the metals methods (i.e., EPA 200.7 and EPA 200.8) that specify the use of a calibration blank and a minimum of one or more calibration standards fall under section 1.7.1.1(l)? ICP methods are mentioned as examples for this clause in the TNI Calibration Guidance Document.

As specified within EPA 200.7 and EPA 200.8, more than one calibration standard is allowed, both methods just require a minimum of one calibration blank and a single calibration point. Linear regression is also acceptable in both methods.

For EPA 200.7 and EPA 200.8, is the lab allowed to analyze more than one calibration standard and still fall under the requirements in 1.7.1.1 (l) or, when more than one calibration standard is analyzed, does it default to the linear regression requirement in 1.7.1.1(f) which requires a minimum of five calibration standards? In other words, is it acceptable to use 2-4 calibration standards for EPA Methods 200.7 and 200.8 and maintain compliance with the 2016 TNI Standards?

TNI FINAL RESPONSE:

When test procedures specify and the laboratory chooses to utilize the single calibration point and a zero point, then they fall under the requirements of 1.7.1.1 (l). However, when test procedures specify, or the laboratory chooses to utilize more standards that would then fall under the restrictions of 1.7.1.1(f).