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

Collect your samples

Sample Preparation

Material needs to be dry and homogenous

Organisms can be analyzed wholeif small enough

Separate samples are required for hydrogen and oxygen

Sample Weights

Sample should contain:400 µg oxygen

80 µg hydrogen

Encapsulating SamplesWeigh samples into

silver capsules

A crimper plate helps shape capsules

The Good

The Bad

The Ugly

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

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

International Shipments

Use a shipping company that brokers their own packages (such as Fedex or DHL)

Customs documentsSpecify plant genus and species

Specify for “chemical analysis”

Permits are required for bird feathers

Email SIF@ucdavis.edufor the appropriate permit

Paperwork

Complete an Analysis Order Form for each analysis type

Complete a sample list for each Analysis Order From

Email forms to sif@ucdavis.edu

Include printed copies with samples

IRMS Basics

(1) Ionize gas

(2) Focus ion beam

(3) Deflect ions

(4) Detect masses

Pyrolysis (High Temperature)TC/EA-IRMSHD & 18O in solids

H2

CO

Gas separation in GC column

CombustionReactor (1400°C)

GCColumn

H2OTrap

Flow toIRMS

HeFlow

Auto sampler

Chromatography

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

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

Raw Data

Reviewed in reprocessorPoor chromatography

Evaluate reference gas values

Confirm placement of standards

Hydrogen Corrections

All corrections are performed on raw ratios

Memory, if needed

Drift over time

H3+ / Size correction

Scale expansion

Oxygen Corrections

Memory

Drift

Size

Scale expansion

Exchangeable hydrogen

Carboxyl and hydroxyl groups will exchange hydrogen atoms with water vapor

Results in shift of deuterium value

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

Exchangeable Hydrogen - Keratin

Correcting to known values of keratin standards determines value of non-exchangeable hydrogen of keratin samples

Only works for keratin

Exchangeable Hydrogen

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

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

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