IAEA Reference Materials
Reference
Sheets
IAEA-156
RADIONUCLIDES IN CLOVER
Intended
Use
This
sample is intended to be used as a reference material for the measurement
of radionuclides in vegetation samples. It can also be used as a quality control
material for the assessment of a laboratory's analytical work, for the validation
of analytical methods and for quality assurance within a laboratory.
Origin
and preparation of the material
The
clover sample was harvested from a small geographical region in Austria in
the summer of 1986. It was anticipated that the material would be contaminated
with radioactive fallout resulting from the Chernobyl incident in April 1986.
A bulk sample
of approximately 1000 kg of the raw clover material was obtained by the Agency’s
Laboratories at Seibersdorf. The material was air dried and then ground to
give a grain size below 0.3 mm before being homogenized in agricultural animal
nutrition mixer. The material was dispensed into plastic bottles in 250 g
units without any further processing. Subsequently, the samples were irradiated
to a dose of 2.5 x 104 Gy using a 60Co source to ensure
long-term stability of the material by inhibiting microbial action.
Date of Release:
January 1991
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Unit Price:
50 €
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Unit Size:
250 g
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| Producer:
Chemistry Unit Agency's Laboratories, Seibersdorf A-2444 Seibersdorf, Austria |
Supplier:
Analytical Quality Control Services Agency's Laboratories, Seibersdorf A-2444 Seibersdorf, Austria |
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Reference Sheet:  IAEA-156(.pdf) |
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Reference
Date for decay correction: 1st August 1986 |
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Number of accepted laboratory results which were used to calculate the
recommended values and their respective confidence intervals about the
mean value. |
| (R/I) | Classification
assigned to the property value for Analyte (Recommended/Information) |
The
values listed above were established on the basis of statistically valid results
submitted by laboratories which had participated in an international intercomparison
exercise organized during 1989. The details concerning the criteria for qualification
as a recommended value can be found in the report (IAEA/AL/035) "Report on
the Intercomparison Run IAEA-156: Radionuclides in Clover" [1]. This report
is available free of charge upon request.
Homogeneity
The
homogeneity of the bottled material was screened by comparing the 40K
and 137Cs gamma count rates in all bottles used for the intercomparison,
chosen at random from the whole production run. The variability of all of
the measured count rates fell within the interval predicted from counting
statistics and on this basis the material was considered to be homogeneous
for a sample size 250 g.
Dry
weight determination
All
recommended values are expressed on a dry weight basis. Therefore the dry
weight must be determined at the time of analysis, using separate sub-samples
of at least 500 mg dried to constant weight in a drying oven set to 105 °C.
Subsequent weighings should differ by less than 5 mg.
Instructions
for use
The
recommended sample size for analysis is 250 g. Analysts are reminded to take
appropriate precautions in order to avoid contamination of the material during
handling. No special precautions are required for the storage of this material.
References:
| [1] |
Last updated 30 March 2004
