time-weighted average sampling

synonym: TWA sampling
https://doi.org/10.1351/goldbook.10189

A passive sampling or active sampling strategy over a relatively long time, during which the amount of analyte(s) extracted is proportional to its average (mean) concentration over that time.

Source:
PAC, 2016, 88, 517. (Glossary of terms used in extraction (IUPAC Recommendations 2016)) on page 526 [Terms] [Paper]