Sample Material
Sediment and rocks, various biological materials (e.g., feathers, plant material), and some liquids (e.g., blood, honey) that can be dried down.
Sample Preparation
All solid samples submitted for isotopic analysis MUST be homogeneous, fine-grained powders. Liquids must be pipetted into tin cups and then air-dried (or freeze-dried).
Sample Weight
Dependent on the carbon and/or nitrogen content of the sample material. To aid in sample collection, Table 1 provides a rough idea of the amount of sample that maybe required. To determine the actual required weight, contact the lab manager BEFORE weighing your samples.
Table 1.
| Sample Type | Approximate Weight |
|---|---|
| Sediments, soils | 10 to 50 mg* |
| Wood, seeds, peat (C only)Wood, seeds, peat (C only) | 1 ± 0.2 mg |
| Wood, seeds, peat (N only) | 5 to 20 mg |
| Animal, fish, insect tissue | 1 ± 0.2 mg |
| GFF filters | Highly variable |
Additional Information
Concentration data MUST be provided when samples are submitted. At this time we do NOT analyze isotopically enriched samples. For samples with high C/N ratios (>20) it is not possible to obtain C and N isotopic data on the same aliquot of material. In this case, two separate analyses, one for δ13C and one for δ15N, will be necessary. Contact lab manager for further information.
Precision
±0.10 permil for δ13C and ±0.20 permil for δ15N
Method
The samples are weighed into tin cups (5x9 mm, Costech #041077) that are then folded into “tiny balls” and placed in a 96-well sample tray (Costech #080016). The sample name, weight and sample tray hole ID (e.g., A1 to H12) are recorded. If you are unable to weigh your samples OSSIC Staff can weigh them for a fee.
Prepared samples are loaded into an Autosampler along with the isotopic lab standards that have been calibrated against various international standards (e.g., USGS40, USGS41, IAEA-600, USGS25, IAEA-N1, IAEA-N2, IAEA-CH-6, USGS24). Samples are then flashed combusted at >1000°C using a Thermo Flash EA (elemental analyzer). The resulting CO2 and N2 are then analyzed by continuous-flow mass spectrometry using a Delta-Q isotope ratio mass spectrometer.
