Analysis of Water ¹⁸O and D/H by Laser-Absorption Spectroscopy

The SIF provides simultaneous analysis of ¹⁸O/¹⁶O and D/H isotope ratios in liquid water samples using an LGR DLT-100 (Los Gatos Research, Inc., Mountain View, CA, USA). Each sample is injected 6 times, the first 3 injections are discarded to eliminate memory effects, and the average of injections #4-6 is used for isotope ratio calculations. Working standard waters calibrated against NIST standard reference materials (VSMOW, GISP, SLAP), are inserted in the sample sequence (usually before and after each group of 6 unknowns). Sample isotope ratios are adjusted to working reference waters. Precision is normally <0.8 per mil for DH and <0.3 per mil for ¹⁸O.

Sample preparation

Submit samples in standard autosampler vials (volume: 2 mL, 12 mm O.D. x 32 mm length) with screw caps (regular 9-425 or wide-mouth 10-425). Use conical bottom vials for low-volume samples (less than 200 uL). Minimum volume is 50 µL; preferred volume is 1 mL. Please do not fill vials more than half full. Use vials with a write-on patch or use clear tape and permanent marker to label vials. Do not wrap vials with opaque marking tape – this makes it difficult to view liquid level. Samples should be kept refrigerated and in the dark. Additional preservation is not necessary. We do not accept samples preserved with HgCl2.

Organizing samples
In order to use the correct reference waters, please group water samples into the following classes:

Pricing

*Five sample minimum (due to number of references needed for analysis)

Shipping

Carefully package groups of exetainers in ziplock bags, small boxes, or their original boxes. Then package these sets in a larger sturdy box with styrofoam peanuts or bubble wrap. Make sure the samples are very secure, loose vials can break during shipping. Coolers will not be returned.

*NEW* Please complete an Analysis Order Form and Sample List for your samples. E-mail the completed forms to sif@ucdavis.edu and 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 recommend completing a separate form for each type of analysis.

Contact information
UC Davis Stable Isotope Facility
Department of Plant Sciences
One Shields Avenue, Mail Stop 1
Davis, CA 95616
USA

Phone:(530) 754-7517, Fax: (530) 752-4361
E-mail: sif@ucdavis.edu

Supplies

Choose any standard 2-mL 12x32 mm autosampler vials. The following is a list of the vials we use. Others are available from a variety of suppliers. We suggest screw-top vials with write-on labels. Both regular (8 mm) and wide-mouth (10 mm) closures are acceptable.

Tips

1) Fill vials no more than half full.

2) Avoid over-tightening caps

3) Note which samples, if any, are enriched and we will run them separately with the appropriate reference waters.

4) Do not freeze water samples in glass vials.

Updated June 18, 2009