Sample Preparation


Sample Submission

UC Davis Plant Sciences

Oxygen (18O) and Hydrogen (D/H) Water Sample Preparation and Organization

The standard volume for water samples is 1-1.4 mL in a 2 mL GC vial. Contact the SIF about low volume samples. Use vials with a write-on patch or use clear tape and permanent marker to label vials. Samples should be kept refrigerated and in the dark for long-term storage. Use minimal headspace for shipping and storing water samples. Additional preservation is not necessary. We do not accept samples preserved with mercuric chloride (HgCl2) or poisoned with sodium azide (NaN3).


Samples will be stored for 3 months post-analysis and then discarded. Please review your data within this window.



Submit samples in standard autosampler vials (volume: 2 mL, 12 mm O.D. x 32 mm length) with wide-mouth 10-425 screw caps and double coated (PTFE/silicone/PTFE) septa. Samples not submitted in autosampler vials will be charged a transfer fee (see Pricing).


For low-volume samples (less than 250 ┬ÁL), please contact us to discuss your low-volume samples.


The following is a list of the vials we use. Other suitable vials are available from a variety of suppliers. We suggest screw-top vials with write-on labels. Only 10mm closures are acceptable.

Manufacturer / Part# Description
National Scientific / C4010-1W Vials, 2 mL, 10 mm screw thread, clear glass, write-on patch
National Scientific / C4010-40A Screw caps with septa, 10 mm (PTFE/Silicone/PTFE)
National Scientific / C4012-25 Storage rack for 50 vials, polypropylene, without lid
National Scientific / C4011-25 Storage rack for 100 vials, polystyrene, with lid


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




Natural Abundance

Up to 60 per mil

Up to 6 per mil

Low Enrichment

60 to 1690 per mil (0.042 at-%)

6 to 263 per mil (0.25 at%)

High Enrichment

Over 1690 per mil (>0.042 at-%)
not accepted

Over 263 per mil (>0.25 at%)
not accepted


For tracer studies, estimates on isotope values are required and samples must be organized by increasing enrichment.


Saline samples must be clearly marked with an estimate of the salinity. Organize saline samples in order of increasing salinity. Units of ppt or mS/cm are preferred. Organize water samples in order of increasing conductivity.


Turbid water samples or water samples containing precipitate must be filtered prior to analysis. If SIF determines a water sample requires filtering, a $5.00 fee will be charged per sample for this service.


The SIF only analyzes samples with a pH between 5 and 9. Samples outside this range must be neutralized prior to shipment to the SIF.



Carefully package racks of vials 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. If samples must be shipped with a refrigerant, be sure to insulate your samples from freezing. Avoid using dry ice as a refrigerant, as samples in direct contact with a refrigerant like dry ice will crack during shipping. Coolers will not be returned.

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.

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