What goes wrong

The holding time expired

Updated October 2026

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The range is enormous The clock starts at collection Which makes it a purchasing question Exceeding it is not a judgment call Record the collection time on the container Build slack into the plan Agree receiving hours with the laboratory first References

A holding time is a hard edge. Past it the number is not defensible, regardless of how carefully the analysis was run.

The range is enormous

Table II runs from eight hours for the bacterial tests to twenty-eight days for ammonia, with thirty-six hours for toxicity and fourteen days for acidity and alkalinity. Those are different logistics problems, and a sampling run collecting several parameters has several clocks running at once.

The clock starts at collection

Not at receipt, not when the lab opens. An eight-hour window collected at nine in the morning is gone by five, which in practice means same-day courier and a laboratory that has agreed in advance to receive it.

Which makes it a purchasing question

Short holding times mean more frequent, smaller shipments and more containers in circulation. A lab planning its consumables without knowing its holding times will order the wrong quantities and the wrong mix.

Exceeding it is not a judgment call

The regulation provides a formal route to alternate procedures through the Regional Administrator and states that an analyst may not modify preservation or holding time requirements unless those requirements are met. Running it anyway and noting it is not a substitute.

Record the collection time on the container

If the time is not on the label, the holding time cannot be demonstrated. That is a chain of custody point and it is the single most common gap in informal sampling.

Build slack into the plan

Weather, traffic and a courier that missed a pickup all consume the window. Planning a collection to use the entire holding time leaves no margin, and the sample is unrecoverable when it goes.

Agree receiving hours with the laboratory first

A short holding time is only workable if somebody is there to receive and start the analysis. Sampling on a Friday afternoon against an eight-hour window is a wasted trip, and it is a scheduling conversation rather than a technical one.

References

40 CFR 136.3, Table II — Required Containers, Preservation Techniques, and Holding Times, which prescribes the container material, the preservation and the maximum holding time per parameter. Footnote 1 defines the codes: “P” is polyethylene, “FP” is fluoropolymer (PTFE), “G” is glass, “PA” is any plastic made of a sterilizable material. law.cornell.edu

Written from federal regulation, not from a bench. Where a method specifies a container, a preservative or a holding time, the method governs and nothing here overrides it. Read the method you are running rather than a summary of what methods generally say.