Airtight coring devices

Soil samples for VOC analysis are collected into airtight coring devices or into preserved VOA vials. Soil samples for SVOC, metal, and inorganic parameter analyses are collected into brass or stainless steel core barrel liners, acrylic liners, or into glass jars with PTFE-lined lids. The liners are capped with PTFE sheets and plastic caps. 

Common to all airtight coring device and autosampler vial sampling ... 

Sampling into airtight coring devices works best for relatively cohesive yet uncemented soils. This technique is not applicable for soils, which contain gravel or rocks or are too hard (cemented) for the device barrel to be pushed into the soil. Soil, which is too sandy or is excessively wet will allow easy penetration with the barrel, however if it is not sufficiently consolidated, it may fall out of the barrel before it is capped. 

To sample with airtight coring devices, we must have access to exposed soil, which may be the ground surface, the bottom and sidewalls of an excavation, the stockpile face or side, or soil in the excavator bucket. We may also apply this technique for sampling of subsurface soil brought to the ground level in a split spoon sampler. 

The laboratory has several preservation options for samples in airtight coring devices, as specified in Table 3.2, after they have been received at the laboratory ... 

Option 1. Store in the airtight coring devices at 2-6°C analyze within 48 hours of collection. Prepare for analysis as described in Option 4. 

Option 3. Extrude the soil from the airtight coring devices into pre-weighed, labelled autosampler vials with PTFE-lined septum caps a magnetic stir bar and 5 ml of analyte-free water, preserved with sodium bisulfate to pH<2. Weigh to determine the sample weight. This method is appropriate for soils that will not effervesce in a reaction with the acidic water solution. A sample prepared in this manner is ready for analysis. Store at 2-6°C, analyze within 14 days of collection. 

Practical Tips Sampling with airtight coring devices... 

Get spare airtight coring devices for backup in the field. 

If soil is too loose or wet to stay in the airtight coring device, use a spoon or a spatula to keep it in place until you cap the device. 

Plan to spend approximately 25 percent more on VOC analysis when using airtight coring devices. 

When sampling with airtight coring devices without methanol preservation backup, anticipate the possibility of deficient analytical results because sample dilution is not possible. 

If the soil is not conducive to sampling with airtight coring devices or cut-off syringes and low VOC concentrations are a matter of concern, we may revise the procedures and collect the needed 5 g of soil with a spatula followed by placing it into a vial. The key is to do it fast in order to minimize the soil exposure to air. 

This type of sampling has the same limitations as sampling with airtight coring devices it is not suitable for soils that contain carbonates, and samples cannot be diluted or reanalyzed, unless one aliquot out of three is preserved in methanol. Studies have shown that frozen storage without the addition of water yields the most consistent results (Zimmerman, 2000). 

Inexpensive disposable non-hermetic plastic soil sampling syringes are available from several manufacturers. These devices are not suitable for storing and shipping samples, only airtight coring devices are. 

If sampling for VOC is required, use an airtight coring device and quickly collect samples from the ends of the middle liner. Cap the lower liner with PTFE sheets and plastic caps, label it, and place on ice. 

Airtight coring Refrigerated in coring device at 48 hours of collection1... 

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