Frequent Questions

What is the EPA’s position with regard to extending a holding time for frozen soil samples?

What is the EPA’s position with regard to extending a holding time for frozen soil samples? For example, can the holding time be extended to one year for PAHs by SW-846 8270?

 

Table 4‐1 in Chapter 4 of SW‐846 presents the holding times recommendations for the EPA Office of Resource Conservation and Recovery (ORCR) with respect to organic analytes by SW‐846 methods.  Footnote "a" of Table 4‐1 states: “The information presented in this table does not represent EPA requirements, but rather it is intended solely as guidance.  Selection of containers, preservation techniques and applicable holding times should be based on the stated project specific data quality objectives.”

Alternative preservation and/or holding times are difficult to apply universally.  A study using archived samples can be performed (for example) but the conclusions are very likely to be applicable only to the actual samples included in the study.

It is important to note that other federal and state government agencies may impose additional sample storage and holding time requirements than the ones recommended in SW‐846 Chapters 3 [for inorganics] and 4 [for organics] and specific methods [e.g., Method 8270D for semivolatiles] for their program or project use and needs.

Laboratories should consult data users and adhere to the sample storage and holding time requirements stipulated in the project QA plans to ensure generated data meets specific program and/or project needs.

 

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