SIREAL maintains an LGR liquid water isotope analyzer with which we may simultaneously measure δ2H and δ18O from water samples using laser absorption technology.

Water_Analyzer
The LGR liquid water analyzer is the black box. In the foreground is the PAL autosampler for taking water from vials and injecting it into the analyzer.

Our methods

Approximately 1.5 mL of water is placed into a 2 mL vial. Caps with self-sealing piercable septa close the vials.

Vials for water analysis
Vials for water analysis

Approximately 900 nL of water is injected and vaporized in a heating block and brought into a laser chamber. A laser is shot through the vapor, and the rate of attenuation of absorption peaks is used to calculate delta values.

At SIREAL, one analysis is 14 individual injections with the first three ignored due to memory effects and the remaining good injections are averaged to provide analytical error.

Further, for each sample the 14-injection analysis is repeated at least twice per water sample.

Our standards are deionized water directly from our tap and a mixture of deionized water and antarctic glacial water, both calibrated to the V-SMOW scale using NIST standards. The values of our standards bracket most natural surface waters, resulting in robust, accurate results.

Rates

Rates are $20 per sample. There is no additional charge for replicates or standards. We only charge for successful analyses.

Packing your samples

Samples should be sent in clearly labeled vials (both caps and the sides of the vials). Samples travel best in 15mL vials that are sealed with parafilm (or similar), then taped over again with packing or duct tape and packed in plastic bags. As best as possible, there should be no air sealed into the vial with your water.

Our analyses only require 1.5 mL, but extra water means that we can do replicate analyses if necessary.

Salty and brine-y waters are more challenging to analyze. Please contact us if your waters may have high levels of dissolved salts.

Waters with volatiles mixed in, like alcohol, cannot be run on the LGR.

Questions

If you have questions or concerns, please contact Penny Higgins at pennilyn [dot] higgins [at] rochester [dot] edu.