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 whole
if small enough
Separate samples are required for
hydrogen and oxygen
Sample Weights
Sample should contain:
400 µg oxygen
80 µg hydrogen
Encapsulating Samples
Weigh samples into
silver capsules
The Good
The Bad
A crimper plate helps
shape capsules
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 documents
Specify plant genus and species
Specify for “chemical analysis”
Permits are required for bird feathers
Email SIF@ucdavis.edu
for 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
(3) Deflect ions
(2) Focus ion beam
(1) Ionize gas
(4) Detect masses
Pyrolysis (High Temperature)
TC/EA-IRMS
HD & 18O in solids
He
Flow
Auto sampler
Flow to
IRMS
CO
H2
Gas separation in GC column
Combustion
Reactor
(1400°C)
H2O
Trap
GC
Column
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, IAEA602, 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 reprocessor
Poor 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 nonexchangeable 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