Water - δD, δ17O, δ18O, Δ17O
We employ the Picarro L2140i water isotope analyzer for analysis of δD, δ17O, and δ18O. We routinely compare results from this instrument to the traditional water fluorination IRMS technique that we also employ. We are tied to the VSMOW international scale via VSMOW and SLAP for our water isotope measurements. 300 uL vials are loaded with 200 uL of sample or reference water and placed in a PAL autosampler tray. The δD, δ17O, and δ18O are measured 6-10 times for each vial from a 2 µL water injection. Between each injection, the cavity is purged with dry air and partially evacuated with a small pump. We maintain a suite of in-house reference waters measured against VSMOW and SLAP using GISP as a quality standard.
We accept samples for water Δ17O analysis on a collaborative basis. The first step, then, is for you to tell us about the goals and purpose of the measurements. If needed, we will work with you to design an appropriate analysis strategy. You can choose to visit IsoLab and perform analyses yourself, or we can analyze the samples for you. We will then work together when interpreting the data. We would discuss the plan at length and make sure the data make sense for you to interpret. We are not able to do “contract” work (i.e., analyze samples without knowing what they are or taking part in the interpretation) because the method is so time consuming, and it is new enough that issues of standardization and calibration make it important to work out with an expert on a case-by-case basis. But as long as it involves scientific collaboration and we get to do quality control on the final dataset, we welcome visitors and/or samples. We typically schedule analyses ~3-6 months in advance.
To calculate costs start with our rates page. If you send someone here to learn the method and do the analyses, the cost is calculated using the "Off Campus Funding, Lab Provided Labor" lane until the visitor is independent in analysis and data reduction (three days seems to be the minimum) then the "Off Campus Funding, User Provided Labor" for every day after that. If we run your samples for you, use the "Off Campus Funding, Lab Provided Labor" lane. These rates are per analysis not per sample and we require at least triplicates for a sound interpretation (# of samples x # replicates = total analyses).
We prefer a minimum of 5 mL of sample in a labeled, water-tight, plastic or glass container with simple legible sample IDs. We need to know if it is fresh or salt water.
Standard Operating Procedures
- Steig EJ, Gkinis V, Schauer AJ, Schoenemann SW, Samek K, Hoffnagle J, Dennis KJ, Tan SM. (2014) Calibrated high-precision 17O-excess measurements using cavity ring-down spectroscopy with laser-current-tuned cavity resonance. Atmospheric Measurement Techniques 7. doi: 10.5194/amt-7-2421-2014
- Schoenemann SW, Schauer AJ, Steig EJ. (2013) Measurement of SLAP2 and GISP δ17O and proposed VSMOW-SLAP normalization for δ17O and 17Oexcess. Rapid Communications in Mass Spectrometry 27. doi: 10.1002/rcm.6486.