🎈 Public Lab: Does keeping a bucket sample cold extend the time you have to get it to a lab for testing?

Question: Does keeping a bucket sample cold extend the time you have to get it to a lab for testing?

by stevie | February 09, 2022 21:00 | #30014

We've been struggling to find a lab to do testing for bucket samples in the greater New Orleans area. Does keeping a sample refrigerated extend the time frame we have to get to a lab for testing? I know the bucket samples generally need to get to a lab within 24hours.

1 Comments

A researcher at the EPA reported a study back in 2007, testing how samples of certain volatile organic compounds (VOCs) in Tedlar bags are affected by time and temperature. Their presentation is here: https://iavi.rti.org/assets/docs/WorkshopsAndConferences/09-Paul_AEHSTedlar2007.pdf

The general issue seems to be that VOC concentrations in the sample could decrease over time if the gases leak or react with the Tedlar bag material; but concentrations could also increase over time if chemicals from the bag itself leached into the sample. It depends on what particular compounds are in the sample and what material the sampling container is made of.

The report linked above shows some of the VOCs they tested...

"...show concentration loss at one week to be <20%"

and

"No consistent differences were seen between storage at 15ºC and 25ºC; however, lower concentrations would be expected at lower temperatures due to loss from condensation."

It'd be difficult to apply these results broadly to air samples, though, because it does depend on what's in the sample.

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