Soil Sampling for Volatile Organic Compounds

Updated November 25, 2016

Soil sampling for Volatile Organic Compounds (VOCs) has changed in 2011 in Ontario. Soil samples used to be submitted directly to the laboratory for preservation prior to analysis, however, due to loss during transport, it was changed that soil samples that required VOC analysis would be preserved in the field. Essentially, the steps that were taken in the laboratory were moved to the field.

There are several optional instruments that are available for use to collect approximately 5 g of soil. I have been using the Terra Core® Samplers as shown below.

Terra Core® Samplers

Some laboratories also supply cut of plastic syringes or something called an En Core® Sampler. I personally don't have one. but the laboratory we use has documentation on it.  If you follow the link below:

http://www.agatlabs.com/news/Ontario_Regulations/PDF%20Files/ON_EnCore_Facts_SCR.pdf

The Terra Core® Sampler is two (2) pieces of plastic that allows soil to be collected by firmly pressing the void tip into the area of concern while holding the upper handle. The smaller plastic piece is later used to push the 5g soil sample out of the sampler and into the preservative.

Essentially two pieces of plastic

In Ontario, the methanol preservative is placed into a 40 ml vial as shown below:

Methanol inside a 40 ml Vial

The laboratory weighs the vial prior to the consultant's use. The vial is weighed again when submitted to determine the weight of the soil sample. As methanol is volatile, it is common that if the vial is kept on the shelf for too long that the amount of liquid is diminish. The consultant will need to check to make sure the meniscus line coincides with the line drawn by the laboratory as shown below.

Methanol meniscus line matches laboratory line

The VOCs captured this way would rather be in the methanol than the air. The only downside to this method is that you will not be able to get a reading for metahnol (if that is the pollutant of concern) and the laboratory cannot determine the moisture content of the sample. The moisture content of the sample is determined by providing the laboratory with additional jarred samples with no preservative.