Methane (CH₄) Sample Preparation
 

Gas samples should be sent in septum-capped vials preferably at atmospheric pressure (~100 kpa) but pressures up to 200 kpa are acceptable. Sample vials are 12 mL Exetainers (Labco Ltd, High Wycombe, UK), but others may be acceptable by prior arrangement. Please note, the wide (###W/W) 12 mL Exetainers supplied by Labco do not fit our autosampler trays and should not be used (see supplies table below). Sample containers should be evacuated prior to sample collection. Label each vial with a unique ID# as your data will reference your samples using this ID.

Gas concentration data (ppm) are required for each sample.  For dissolved methane samples, the gas concentration (ppm) in the headspace is required.

Separate gas sample vials are required for each isotope (²H, ¹³C). If sending water samples for analysis of dissolved CH₄, a minimum of 12 mL of water sample is required for each isotope.

Dissolved methane samples may be preserved through the addition of HCl to a pH < 2. Alternatively, water samples may be shipped in rubber butyl septum capped vials with no headspace bubbles, and kept refrigerated without freezing. Due to university regulations, we cannot accept samples preserved with mercuric chloride (HgCl2).

In order to ensure the best possible analysis, test samples should accompany any enriched samples when the maximum level of enrichment is unknown or cannot be estimated. Questions? Contact Rick Doucett

Supplies

*Note: Labco has a wider vial style that ends in ###W/W.  We DO NOT accept these vials at the SIF because the vials are too wide for our autosampler racks.