Stable Isotope Facility

Nitrogen (N₂) & Nitrous Oxide (N₂O) by Trace Gas-IRMS
Sample Preparation

Gas samples must be supplied in septum capped vials preferably at atmospheric pressure (~100 kpa) but pressures up to 200kpa are acceptable. Over-pressurized vials may burst during shipping. The exetainers should be evacuated prior to sample collection. Label each vial with a unique ID# as your data will reference your samples using this ID.

Sample vials must be provided in 3.7, 4.5, 5.9, or 12mL Exetainers with plastic screw-caps (Labco Ltd, High Wycombe, UK), or in 20mL (23x75.5mm) headspace vials (Grace, Deerfield, Illinois U.S.A.). Labco has a new, wide vial that ends in ###W/W. We DO NOT accept these vials at the SIF because the vials are too wide for our autosampler racks. For ordering information, see the Supplies section below.

Other sample vials may be acceptable, but only by prior arrangement with Chris Yarnes.

Sample vials or sample preparations not conforming to SIF requirements will not be analyzed.

If samples are for the dissolved gases of waters, samples may be preserved using 1mL of 50% w/v ZnCl₂. Due to university regulations, we cannot accept samples preserved with HgCl₂. All samples originating from waters should be stored immersed in a secondary container that is filled with the source water (see Dalsgaard et al. 2000 for detailed procedures). Note: we require at least 25mm of headspace to allow for needle penetration during analysis.

If the analysis of enriched samples > 10 atom % is desired, or you do not know your range of sample enrichment, we require that you supply a small set of test samples or replicates that can be used to determine the appropriate instrumental configuration for your experimental samples.

Samples requiring extensive handling by the SIF (i.e. filtering, sorting, cleaning, transfer) will be charged, at minimum, an additional $1.00 handling fee per sample.

Helpful Resources

Hamilton, S.K. and N.E. Ostrom 2007. Measurement of the stable isotope ratio of dissolved N2 in 15N tracer experiments Limnol. Oceanogr.: Methods 5: 233–240.

Dalsgaard, T., et al., 2000. Protocol handbook for NICE—nitrogen cycling in estuaries: a project under the EU research programme: Marine Science and Technology (MAST III). National Environmental Research Institute, Silkeborg, Denmark

Laughlin, R.J. and R.J. Stevens. 2003. Changes in composition of nitrogen-15-labeled gases during storage in septum-capped vials. Soil Sci. Soc. Am. J. 67:540–543.

LINX II (Lotic Intersite Nitrogen eXperiments) protocol: http://www.biol.vt.edu/faculty/webster/linx/linx2proto-rev5.pdf

Shipping
Carefully package groups of exetainers in Ziplock bags, small boxes, or their original boxes. Then package these sets in larger, sturdy boxes with Styrofoam peanuts or bubble wrap. Make sure the samples are very secure; loose vials can shatter during shipping. Gas samples do not require refrigeration during shipping.

Please complete and submit the online Analysis Order Form and Sample List for your samples. Also, be sure to include a printed copy with your samples. The SIF uses this form to track your samples and to contact you regarding receipt of samples, data, and invoicing. For mixed analysis requests, we require the completion of a separate form for each type of analysis.

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*
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 new, 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