EPA Revisions to Method 301 Validations

On May 10, 2011 the U.S. Environmental Protection Agency issued a revision to its Method 301 Validation process. Method 301 is used when a source owner or operator proposes to use a new or alternative source emissions sampling method to meet an EPA compliance requirement for stack testing.  The method specifies procedures for determining and documenting the precision and bias of measured concentrations from various media (e.g., sludge, exhaust gas, and wastewater) at the level of an applicable standard for a source. 

Revised Rule: http://www.epa.gov/ttn/oarpg/t3/fr_notices/20110512method301.pdf.

Fact Sheet:  http://www.epa.gov/ttn/oarpg/t3/fact_sheets/20110512method301fs.pdf

Method 301 affects/applies to you if you want to propose a new or alternative test method to meet an EPA compliance requirement.

You would use Method 301 whenever you propose to use a test method to meet an EPA compliance requirement other than a method required under a 40 CFR part 63 rule. The method specifies procedures for determining and documenting the precision and bias of measured concentrations from various media (e.g.,

sludge, exhaust gas, wastewater) at the level of an applicable standard for a source. Bias (or systemic error) is established by comparing your proposed method against a reference value. A correction factor is employed to eliminate/minimize bias. This correction factor is established from data obtained during your validation test. Methods that have bias correction factors outside a specified range are considered unacceptable. Method

precision (or random error) at the level of the standard must be demonstrated to be as precise as the validated method for acceptance.

EPA proposed five major technical changes to Method 301. These technical changes include the following:

1. Replacing the Practical Limit of Quantitation (PLQ) with a procedure to determine the Limit of Detection (LOD)
2. Revising the bias acceptance criteria and eliminating correction factors
3. Revising precision acceptance criteria when using analyte spiking
4. Allowing analyte spiking even when there is an existing test method
5. Establishing new procedures for ensuring sample stability

Other clarifications from EPA include:

• Amendments to Method 301 do not apply to methods submitted for approval prior to promulgation.
• Method 301 can be used whether or not a validated method exists.
• Inadvertantly, in Section 5 of Method 301, “reference materials” was followed by “(analytes).” This parenthetical was modified for clarification purposes.
• A few commenters expressed concern that the standard against which precision and bias are compared is not required to be compared against a true value, usually a traceable standard. EPA agreed that the reference material should be compared to a traceable standard.
• EPA has approved methods demonstrated with sequential sampling to determine the precision of a proposed alternative method in the past. The final method explicitly states that sequential sampling procedures are allowed.
• If an alternative method is being compared to a validated test method as part of the Method 301 validation and an audit sample for the validated method exists, then an audit should be used for the validated method.
• Method 301 previously lacked specific procedures for ensuring that samples collected under proposed alternative methods were analyzed within an appropriate time. EPA revised Section 7.4 to include a requirement to calculate the difference in the sampling results at the minimum and maximum storage times, determine the standard deviation of the differences, and test the difference in the results for statistical significance by calculating the t-statistic and determining if the mean of the differences between the initial results and the results after storage is significant at the 95 percent confidence level.  The method will continue to require a precision of ± 20 percent when only the required three runs per test are performed. However, EPA have added an option to allow test methods with a precision greater than ± 20 percent, but less than ± 50 percent, provided that the user collect nine sample runs per test during any compliance testing where the method is used.
• EPA proposed to replace the Practical Limit of Quantitation (PLQ) determination with a procedure to determine the Limit of Detection (LOD), and clarified the terms and equations for that procedure.