What is a holding time, and why do I need to know about it? A “holding time” is the elapsed amount of time from the point of collection to the moment of preparation or analysis. Note that this is not the date/time of receipt at the lab! If samples are analyzed beyond an analytical holding time, the data will be qualified on the analytical report and may not be usable for compliance.

The analytical hold time to a sample is like an expiration date to a carton of milk; past the hold time, analysis technically can still be performed (just as milk may be consumed after it expires), the results, however, in both cases may be unsavory. There are very few allowances for missed hold times and in almost every case, resampling is required.

You should get samples to the lab as quickly as possible, as holding times are different for volume received unpreserved. For example, metals shrink from 6 months to 7 days, nutrients from 28 days to 48 hours, others hold times may even shrink to 24 hours or less! Find out more about preservatives and sample bottles here.

Holding times are easily accessible, as the information is constantly needed (and important!):
From WETLAB’s website here
From the EPA under 40CFR, part 136, Table II
From the NDEP website here
Or, get a hard copy sheet on your next stop into WETLAB

Be aware, hold times can change as methods are updated, so you should contact WETLAB for the most up to date information before you develop your sampling plan.