Sample Temperatures

 08/04/2016

“Samples should be sealed and transported to the laboratory as soon as practicable, using suitable cooling aids (preferably ice bricks or in a refrigerated container) to ensure samples start cooling as soon as possible, and they should be stored in a refrigerator (≤6°C) until analysis.”

NEPM B3 no longer requires samples to be received at the Laboratory at 4°C as long as the client has attempted to cool their samples below ambient.

Temperature control of water samples during delivery to the lab
There is a general conception that sample temperatures must be at 4°C.

Envirolab Group recently in January 2016 tested this common theory that water samples need to be kept cold at 4°C. 

The team firstly took the surface temperature of 104 samples in bottles and jars typically received in eskies at our Envirolab Sydney lab.

As a note, these eskies were from local Sydney clients generally delivered to the lab the same day as sampling. The samples had been placed in the eskies with a mix of both ice and ice bricks.

How many samples are received cold by the lab?
The table below lists the temperature range of the 104 samples. From the table, 31% were received at <5˚C. 28% of eskies were received at 5-10 ˚C, 26% at 10-15 ˚C and 15 % of eskies were >15 ˚C.

So to put those figures another way, 69% of eskies were received at >5 degrees.

Is this a problem?
For distilled water samples in a VOC Vial with no headspace, it doesn’t seem to be a problem. The table below summarizes an additional experiment conducted in February 2016 at Envirolab. Water VOC Vials were spiked with 20ppb VOC’s and stored over several hours at either 8 ˚C, 21 ˚C or 40 ˚C. These VOC Vials were then analysed. As can be seen from the list below of selected VOC’s, there is no significant difference in results across all three temperature ranges.

Conclusion
A headspace free VOC vial of distilled water will not suffer from volatile losses in a warm esky up to 40 ˚C. However, samples with headspace, for instance a poorly packed soil jar, may not have the same outcome.

 

Where to from here?
At a later date, our team will expand this experiment to a combination of real ground/surface/waste water and soils.

For further information on this test or sending a water sample for testing call 1300 424 344 or email David Springer 

Open article as PDF document


News list