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18 O & D/H Analysis of Solids by TC/EA-IRMS. Collect your samples.

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Presentation on theme: "18 O & D/H Analysis of Solids by TC/EA-IRMS. Collect your samples."— Presentation transcript:

1 18 O & D/H Analysis of Solids by TC/EA-IRMS

2 Collect your samples

3 Sample Preparation Material needs to be dry and homogenous Organisms can be analyzed whole if small enough Separate samples are required for hydrogen and oxygen

4 Sample Weights Sample should contain: 400 µg oxygen 80 µg hydrogen

5 Encapsulating Samples Weigh samples into silver capsules A crimper plate helps shape capsules The Good The Bad The Ugly

6 Organizing Trays Load samples across rows of 96-wells trays Do not leave empty wells between samples Label trays uniquely and clearly Place samples for different analyses in different trays

7 Sealing trays For small samples, place an index card or parafilm between tray and lid before sealing Tape lid securely to tray – use lab tape

8 International Shipments Use a shipping company that brokers their own packages (such as Fedex or DHL) Customs documents Specify plant genus and species Specify for “chemical analysis” Permits are required for bird feathers for the appropriate permit

9 Paperwork Complete an Analysis Order Form for each analysis type Complete a sample list for each Analysis Order From forms to Include printed copies with samples

10 IRMS Basics (1) Ionize gas (2) Focus ion beam (3) Deflect ions (4) Detect masses

11 Pyrolysis (High Temperature) TC/EA-IRMS HD & 18 O in solids H2H2 CO Gas separation in GC column Combustion Reactor (1400 ° C) GC Column H 2 O Trap Flow to IRMS He Flow Auto sampler

12 Chromatography

13 Standards - Hydrogen International standard (IAEA-CH-7) and inter-laboratory keratin standards are included in all runs In-house standards have been calibrated against same standards All results are expressed with respect to VSMOW

14 Standards - Oxygen International standards (IAEA-601, IAEA- 602, USGS-8568) are included in all runs In-house standards have been calibrated against same standards All results are expressed with respect to VSMOW

15 Raw Data Reviewed in reprocessor Poor chromatography Evaluate reference gas values Confirm placement of standards

16 Hydrogen Corrections All corrections are performed on raw ratios Memory, if needed Drift over time H3+ / Size correction Scale expansion

17 Oxygen Corrections Memory Drift Size Scale expansion

18 Exchangeable hydrogen Carboxyl and hydroxyl groups will exchange hydrogen atoms with water vapor Results in shift of deuterium value

19 Exchangeable Hydrogen - Keratin Accepted keratin standards allow measurement of keratin samples by “like treatment” Standards and samples equilibrate with lab atmosphere and are analyzed together

20 Exchangeable Hydrogen - Keratin Correcting to known values of keratin standards determines value of non- exchangeable hydrogen of keratin samples Only works for keratin

21 Exchangeable Hydrogen For non-keratin samples, percent of exchangeable hydrogen must be calculated

22 Dual-Equilibration By equilibrating a material with waters of different deuterium values, the percent of exchangeable hydrogen and deuterium value for the non-exchangeable fraction can be determined

23 Oxygen – Memory effect Oxygen is prone to carryover from one sample to the next Varies with age of reactor and ash accumulation Can be corrected for by mass balance Best precaution – run replicates


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