The
Keck-CCAMS facility was set up to expand UC and US capabilities for 14C
measurements in support of research into the carbon cycle and its links
to climate. One of the aims was to minimize measurement cost by
emphasizing large scale projects plus encouraging users to carry out
sample processing at their own institutions. Researchers from other
fields or submitters with fewer than ten samples are encouraged to
contact other AMS facilities or commercial dating services: small
batches or samples from other fields will be run by special arrangement
only. Contact information for other laboratories can be found at the
Radiocarbon journal web site, at www.radiocarbon.org.
Submission process
To send samples to Keck-CCAMS at the UCI for analysis, the following
steps are required:
1. Submitters, and in particular those making their first application,
must make contact with the laboratory to discuss their requirements
prior to actually submitting samples. See contacts for more
info.
2. A submission form plus a sample list provided must be filled out
(see guidance document) for each group of samples submitted and sent to
us via mail, fax or e-mail. A hard copy of both must also accompany the
samples.
3. The
AMS prep. laboratory is currently equipped to handle routine processing
of charcoal, wood, seed, carbonates, animal remains, etc. However, it
is up to the submitter to define and select the materials to be dated:
for example, since you know your samples far better than we do, it’s
your job to pick out the macrofossils or charcoal to be dated from
within the sediment or peat matrix. Specialized services such as pollen
or foram picking or individual compound separation are not offered. We
discourage the dating of bulk soil, peat, or sediments, because those
materials are often a mixture of components with widely differing ages.
The preferred minimum sample size for a 14C measurement is
1 mg carbon. The sample sizes quoted in the table below will yield
approximately this amount, if the samples are well preserved. If this
is not the case, more sample material will be required.
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4. For low-carbon
organic material the carbon content can vary widely and no estimate for
the preferred minimum sample size can be given. Note that smaller
sample sizes can be dated at a reduced precision. For more details
contact us.
5. It is important to try to avoid storage and packing methodologies
that may contaminate your sample. Please follow the guidelines
described below:
_____Never store material under conditions that might allow fungal or
bacterial growth: If possible, try to keep samples frozen or dry.
_____Never handle samples in, or use implements and tools from, labs
where tracer 14C might have been used.
_____Wrap and label each sample individually.
_____ Avoid wrapping samples in paper, or packing in containers that
are lubricated with oil, waxes or any other organic materials. We
prefer to receive samples in small glass or plastic vials, or wrapped
in aluminum foil.
6. If you intend to send samples to us and there is any possibility
that somebody could have used 14C tracer in your facility
(even in the past) contact us first. If necessary we will send you a
monitoring kit for swiping your laboratory and suspect areas, to test
for tracer contaminations. This procedure is important for avoiding
serious consequences involving contamination of your samples and our
laboratory. Check Swipe Protocol (PDF file)
for more information. Also check the
useful tips to avoid 14C tracer epidemics (PDF
file).
7. If samples require additional processing, the submitter will be
informed of the added cost before work proceeds.
8. Results are routinely corrected for isotopic fractionation using
AMS-measured delta 13C ratios, but precise IRMS delta 13C
measurements can be provided at additional cost. In this case, try to
include at least an additional 10% of raw material. Check price
list for more information.
9. Unused sample material will be not being archived or returned,
except by special arrangement.
10. Shipments from U.S. and Canada, we recommend shipping by airmail,
priority mail, or courier. Foreign shipments should be sent by airmail
or international air courier. All samples which must pass through U.S.
Customs should be clearly labeled on outside pack "SCIENTIFIC SAMPLES -
NO COMMERCIAL VALUE". Each shipment should contain a packing list of
samples inside the main box, including the name and address of the
shipper. In addition, the identification code of the sample, laboratory
sample code (when sample was previous treated outside our lab), type of
material and any other relevant information.
11. Our prices for sample preparation and AMS measurement vary
depend on the submitter (UC /non-UC), sample material, pretreatment
required, etc. See our price list or contact us.
12. For payment, see billing and payment procedures.
Please contact us for any question or further details.
IMPORTANT: Do not
send any sample before contacting the Keck-CCAMS personnel.
Guidance
document
Please fill out
the sample
submission form and provide the following additional
information:
A. Brief (a few
sentences) description of the project including overall objectives,
reason for 14C measurements, any relevant previous dating
work, etc.
B. Brief description of sampling
methodology and any pre-treatment already applied (eg, forams picked
from marine sediments, sonicated in alcohol, etc).
C. Sample list: your lab number for each
sample; a descriptive ID if is available (containing eg, stratigraphic
information, species/sample material, etc – core 58PC, 325 cm ,
bulloides); sample type (CO2, macrofossil, graphite, HPLC
fraction, etc); measured or estimated carbon content; approximate
expected age (eg bomb 14C, modern, Holocene, ca. 40ka,
etc).
D. Assessment of possible problems in
interpretation, if applicable.
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