What is sample hold time?

• A. The maximum time a sample can be stored before analysis while still producing valid results.
• B. The minimum time required to transport a sample to the lab.
• C. The time allowed for the lab to analyze a batch of samples.
• D. The duration of field sampling procedures.

Answer: (A)

Sample hold time is the maximum period after a sample is collected during which it can be stored (with proper preservation) and still yield valid analytical results. This window matters because many constituents can change over time—dissolve, volatilize, degrade, or shift due to microbial activity—so testing must occur before those changes compromise accuracy. If analysis happens after this holding time, the results may no longer reflect the water as it was at collection. The other descriptions refer to transport duration, the lab’s analysis window, or field sampling length, which are separate concepts from how long a stored sample remains valid before testing.