Sample Requirements for the MICADAS Gas Interface
Minimum batch size is 20 samples; however, a small number of samples (5-6) may be considered for first time submitters upon request. Samples should yield 100-300 µg C. Any washing or pre-treatment of the samples must be done prior to submission. When submitting, we recommend that the sample list be ordered from expected oldest to youngest ages, if possible, to minimize the carryover effect during GIS analysis.
Carbonate minerals by online Carbonate Handling System (CHS)-AMS
δ13C by IRMS is not available for samples analyzed using CHS-AMS.
Samples need to be weighed out and submitted in special Exetainer vials provided upon request. Accurate weight is requested.
| Typical Sample Size for CHS-> GIS analysis | Minimum Batch size | Required Carbon mass | |
|---|---|---|---|
| Carbonate Sample Types | 20 | 100-300 µg C |
|
| Foraminifera | 1-3 milligram | ||
| Coral | 1-3 milligram | ||
| Mollusc | 1-3 milligram | ||
| Otolith | 1-3 milligram |
Organic carbon (ready to burn) by online Elemental Analyzer (EA)-AMS with optional δ13C
δ13C by IRMS is available for samples analyzed using EA-AMS.
Accurate carbon masses are required. Samples must be weighed into tin cups and compressed into a compact spherical or cubic shape with maximum outer dimensions of 6 mm. We recommend using fresh 5 x 9 mm tin capsules from Costech (code #041077) to match those used internally at NOSAMS. Process blanks for the system have been determined using this capsule and are applied to all results. If using different capsules, please consider submitting a few empty tins so that we can assess the amount of blank carbon in them on the EA (at no charge). Capsules with blank carbon amounts substantially above our internal process blank will be flagged as an alert.
If pre-treated with acid and/or base, samples should be completely neutralized and dried before weighing them into the tin cups. For encapsulation tips for preparing samples in tin cups, please refer to this page provided by the UC-Davis Stable Isotope Facility. Polystyrene cell culture plates are recommended for storing and shipping the packed samples in an ordered labelled tray. Adding an index card under the lid may help prevent dislodging during shipping.
| Typical Sample Size for EA-> GIS analysis | Minimum Batch size | Required Carbon mass | |
|---|---|---|---|
| Organic Carbon Sample Types | 20 | 100-300 µg C |
|
| Plant/Wood | 0.25 - 0.75 mg | ||
| Sediment (OC) | depends on %OC |
Dissolved inorganic carbon (DIC) by online headspace-AMS
δ13C by IRMS is not available for DIC samples analyzed using headspace-AMS.
Liquid DI14C samples need to be injected with a syringe by the submitter into specially prepared septum-sealed screw cap Exetainer vials. The vials, provided upon request, are pre-acidified and pre-flushed with helium at NOSAMS, so poisoning with HgCl2 is not necessary. DIC concentration and sample volume are required. The protocol for collecting liquid samples into Exetainers is available here. For more information, please contact NOSAMS.