Expiration Dates of Environmental Sample Containers
The Environmental/Analytical industry, consisting of both commercial and in-house laboratories performing USEPA Methods on Waste Water, Drinking Water and Hazardous Waste, continues its drive for data that is of “known and documented” quality through its various accreditation bodies (TNI/NELAC, ELAP).
Sample container suppliers are routinely queried by their customers through the audit process. Questions such as, container cleanliness, certification and traceability are typically verified. Audit items are now moving past just product/container suitability and on to product freshness or shelf life.
The ancient USEPA sample container specification, OSWER Directive#9240.05A, did not address container shelf life in specific terms. Vendor warranties are primarily antidotal. Rather a hard expiration date for glass and plastic containers, ESS (Environmental Sampling Supply, San Leandro, CA) provides- “recommended usage dates”. Not knowing storage conditions or exposure, it is hard to predict when a sample containers in not suitable for use. A future date, at the stroke of midnight, doesn’t seem practical. We “recommend” a one year usage date for unpreserved containers and a six month recommended usage date for Pre-Preserved® Containers. This does not mean that past those periods, that the product can’t be used. Since most of our clients are laboratories, they have the ability to spot check/run blanks on their inventory. The recommendation approach also benefits our lab clients who typically give containers free of charge to their consultant clients as part of the analytical service. Firm set expiration dates would result in the return of what most likely would be usable product.
What tends to be of greater concern is the shelf life of containers with a chemical reagents as sample preservatives-PrePreserved® Containers (ESS introduced PrePreserved® Containers in 1989). Guidance in this area is also limited. Chemical manufacturers use the term “chemical retest date” as a close statement to expiration date. Analytical grade reagents typically come with a two year extended retest date. For similar reasons, (chemical manufacturers not wanting to take back product) a recommendation to test two years out provides them cover. To satisfy accreditation standards, ESS includes a product/container manufactured date and reagent retest date on its PrePreserved® Containers.
Vice President, ESS, San Leandro, CA