δ18O (δ2H) analysis of solid samples
- A Thermo Scientific EA IsoLink coupled to a Conflo IV and a Thermo Scientific Delta V Advantage Isotope Ratio Mass Spectrometer is used for d2H and d18O analysis of solid samples.
- Sample materials analyzed in SIBS lab are feather, hair (for H and O), and cellulose, wood (for O).
- Please contact us for guidance on sample sizes, typically on the order of 0.1-0.3 mg.
- We analyze keratin samples for the δ2H and δ18O separately.
- For control for exchangeable H atoms, keratin standards EC1(KHS), EC2(CBS), USGS42, and USGS43 (Scoplen and Qi 2016; Soto et al., 2017) are used. The keratin standards and samples are left in the lab for 5-7 days for hydrogen exchange between lab air moisture and exchangeable hydrogen in keratin (e.g., Wassenaar and Hobson 2003). They are then packed in 3.5x5mm silver capsules (Costech, USA), and kept in a vacuum oven at least for 3 days until the isotope analyses. The samples were loaded in a Zero-blank autosampler immediately (1-3 minutes) after they were out from the vacuum oven, and flushed with helium for at least 20 minutes. A glass carbon tube filled by glassy carbon chips in the EA IsoLink is heated at 1400 °C.
- Long-term variations for the keratin δ2H analysis are better than 1.5 permil.
- For the oxygen isotope analysis, IAEA and USGS standards selected based on your sample materials are used for isotope calibration (e.g., water in silver tube UC03, UC04, VSMOW; Benzoic Acid IAEA-601, 602; Cellulose IAEA-CH3; Wood USGS54, 55; keratin USGS42, 43).
- The oxygen isotope analysis of samples containing nitrogen is performed by separating N and O peaks by more than 250 seconds.
Sample Submission Procedures
- Fill out the “Sample submission form OH_Solid”, and send it to us.
- Make sure samples are dried and ground or cut (depending on sample material).
- If you are sending pre-weighed samples:
- Contact us and ask us how much you need to weigh (generally Cellulose: 0.05mg, Keratin: 0.15mg).
- Weigh your sample in 3.5×5 mm silver capsule (Part #041066) from Costech.
- Pack the silver capsules – make it as small as possible and make sure samples are not spilling out from the silver. Put it in a seat (e.g., A1, A2…H12) of a sample plastic tray from Costech (Part #080016).
- Record the seat position, the sample ID, and the weight in an Excel file.
- Put a lid on the sample tray, and tape it well to avoid move or jump of samples.
- If you are sending samples without weighing:
- Please make sure Sample IDs are clearly shown on labels and samples are ground well.
- Samples should be kept in glass vials with screw caps. In this way, we can easily dry samples in an oven; please avoid plastic centrifuge tubes.
- Send the package to SIBS Lab, 534 John Kimbrough Blvd., 2258 TAMU, Department of Ecology and Conservation Biology, College Station, Texas 77843-2258.
