COSMOGENIC ISOTOPE PREPARATION FACILITIES
The Cosmogenic Isotope Laboratories at the University of Washington
are used to prepare samples for ultra low level isotopic analysis by Accelerator
Mass Spectrometry (AMS). All aspects of the process are covered, from mineral
separation through to loading of accelerator cathodes. We currently prepare
samples for Be-10, Al-26 and Cl-36 analysis, starting from geological materials
such as quartz, calcite and K-feldspar, whole-rock samples, soils, sediments,
water and glacier ice. Samples for Cl-36 and trace chloride measurements
are processed in a separate clean lab, isolated from hydrochloric acid
vapor. Low-level Be-10 and Al-26 extractions from quartz are carried out
under clean conditions in a separate lab from soil and sediment chemistry.
The low-level labs are equipped wih HEPA-filtered laminar downflow cabinets
to minimise particulate contamination. Full procedural blanks are typically
20,000 - 30,000 atoms for Be-10, 10,000 atoms for Al-26, and 5000 - 10,000
atoms for Cl-36.
The files linked to this page describe the procedures we use to extract
and purify Be, Al and Cl for AMS and related analyses. They have been developed,
tested and upgraded over several years, on hundreds of samples, and we
believe they work well. Try them out and see for yourself. We'd be interested
to receive comments and suggestions, especially any that correct, improve
or simplify the procedures. We modify them occasionally, and will try to
keep descriptions on this site up to date.
Some files contain a reference to a published description of the
method. If you adopt one of these methods (which presumably means that
it (a) worked, and (b) helped with a long-standing problem, or (c) rescued
anomalous or misbehaving samples) please cite the reference.
Disclaimer: We assume that users are trained in analytical chemistry
and therefore able to understand these procedures and apply them safely.
The procedures involve highly toxic, corrosive and dangerous reagents.
You must not attempt to use these methods unless you have a clear understanding
of the hazards, safe handling and responsible disposal of the required
reagents, particularly hydrofluoric acid, perchloric acid and beryllium.
Users should also realise that we cannot guarantee these methods in any
way. Procedures may need to be adapted to specific laboratory conditions
or modified to meet the requirements of specific AMS facilities. Though
we think these methods are reasonably robust, they cannot be expected to
cope with the infinite variety of geological samples. It is up to the user
to anticipate problematic samples and adapt the procedures accordingly.
If in doubt, practice on blanks or appropriate test solutions before using
these methods on valued samples.