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UC Davis Plant Sciences



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

Manufacturer / Part#

Description

Unit

Labco / 839W, 739W

Exetainers: 12mL Soda Glass Vials, flat bottomed, labeled, white cap, evacuated (839W) or
non-evacuated (739W)*

Case of 1000

EA Consumables / E2852

(Labco#739W)

12ml Soda Glass Vial Flat bottom-739W- 101x15.5mm Non-Evacuated labelled Seal + White Cap

Pack of 1000

EA Consumables / D2852-100

(Labco#739W)

12ml Soda Glass Vial Flat bottom-739W- 101x15.5mm Non-Evacuated labelled Seal + White Cap

Pack of 100

EA Consumables /

E2885 (Labco#VC309)

E2886 (Labco#VC306)

E2887 (Labco#VC303)

E2866 (Labco#VC301)

Pierceable Cap & Septa:

White VC309

Orange VC306

Grey VC303

Blue VC301

Pack of 1000

Microliter Analytical/ 20-2000-S

Sil Vial Bev Crimp 23x75mm, Clear, 20mL

Pack of 100

Microliter Analytical/ 20-0025-B

Septa, 20mm Gray Butyl Stopper  

Pack of 1000

Microliter Analytical/ 20-0000AS-B

Seal, 20 mm Standard Aluminum 

Pack of 1000

*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.   Supplier: Labco UK + International or Labco USA + Canada








 
e-mail: sif@ucdavis.edu | phone: 530-752-8100 | fax: 530-752-4361
UC Davis Stable Isotope Facility | Department of Plant Sciences
One Shields Avenue | Davis, California, 95616 | USA