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Services
Solid Samples (EA,
TC/EA)
Gas Samples (Dual Inlet, Gas Bench II)
Water Samples (Gas Bench II, TC/EA)
Compound Specific (GC/C)
Data Normalization
and Quality Control Measures
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Solid
samples
EA and TC/EA: We can analyze a variety of
matrices (soil, plant, vertebrate,
invertebrate, organic and inorganic) for C, N, H, O, S stable
isotopic composition or quantitative elemental composition through
dedicated combustion and pyrolysis elemental analyzers.
Samples must be dried and ground to a consistent particle size.
The amount of
sample required is dependent on the sample's elemental composition,
so please contact the laboratory manager (bharlow@wsu.edu)
for the appropriate mass before weighing your own samples. Samples must be
weighed in tin capsules
for 13C, 15N, or 34S analysis,
and silver capsules
for 18O & 2H analysis. Filled and
folded capsules can be shipped in secured 96 position
cell plates.
Dried and ground
samples can be submitted bulk in vials for our staff to weigh into
the appropriate capsule. With this option, we analyze test
samples for elemental composition and determine the appropriate
amount. See additional services or contact the lab manager for
more information.
Special note
on foreign soil analysis: Our laboratory
is approved to receive and process foreign soils regulated by the
USDA and APHIS PPQ. Shipments of these items require special handling
and treatment; please contact the laboratory manager for details.
It is
the responsibility of the sample submitter to determine sample
requirements, concerns or additional preparations required for their
study. Please contact
the laboratory manager before submitting samples (bharlow@wsu.edu).
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Gas
Samples
Dual Inlet: Gas samples are analyzed via our dual inlet
system in flame sealed glass tubes via tube breaker, or lecture bottles or similar that
terminate with 1/4” fittings.
Gas Bench
II: Samples are analyzed in 12-mL vials
with septa caps. In some cases, use of our pre-evacuated vials may
be possible. Contact the lab manager for details.
We use NIST,
IAEA, and lab acquired carbonates digested with 100% H2PO4
for 13C and 18O normalization. QC
carbonate samples, our CO2 monitoring gas and a CO2 flush fill tank
provide monitoring of final calculated delta values.
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Water
Samples
Gas Bench II: Samples are analyzed in 12-mL vials with septa caps. If desired,
our staff can
pipet water samples to vials for a minimal charge per sample. In
some cases, use of our pre-evacuated vials may be possible. Contact
the lab manager for details.
TC/EA:
We use a GC PAL autosampler and modified reactor for liquid injections on the TC/EA.
Samples should be in 2 mL screw top vials (12x32 mm) with 8mm diameter
septa caps.
If desired, WSU laboratory staff can pipet samples into vials for
a minimal charge. In the event of small samples, vial inserts can be used.
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Compound
Specific
GC-C: We utilize an existing GC-MS in the WSU LBB2
unit for assistance with compound identification, retention times,
and methods development. Samples should be in 2 mL screw top vials
(12x32 mm) with 8mm diameter septa caps. In the event of small samples, vial inserts can be used. All derivation
of samples is to be performed by the client. Derivation with methlyboronic
acid (MBA) or trimethylsilyl (TMS) is recommended. Due to the specificity
and time requirement for these analyses, availability is typically
limited to internal clients only. Contact
the lab manager for details.
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Data
Normalization and Quality Control
Instrument
stability checks and necessary calibrations are performed prior to
all analyses.
Instruments are tuned to
exceed factory specifications for linearity, or bias associated with
amplitude. In addition, samples, reference material,
and monitoring gasses are prepared to yield signals of the same
amplitude.
Final isotopic data is calculated using
multi-point normalization
from at least two internal running standards or certified
reference material with a wide span of delta values. All running standards are
calibrated biannual to 3 or more NIST and IAEA
certified reference material. Standards used are selected to be of
a similar matrix and elemental ratio as your samples. For quality control, we
include at least two “blind” QC
samples of similar composition in all sample sequences. Summaries
of these QC standards from multiple analyses, multiple days, and
instruments are available upon request. Our laboratory also
participates in periodic ring tests with multiple
laboratories.
For
a 49 sample EA sequence for CN analysis, this amounts to 12 calibrated references
distributed throughout the run.
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