IAEA Reference Materials
Reference
Sheets
IAEA-405
TRACE ELEMENTS AND METHYLMERCURY
IN
ESTUARINE SEDIMENT
Intended
Use
This
material is intended to be used as a reference material for the measurement
of trace elements and methylmercury (MeHg) in coastal sediments. It can also
be used as a quality control material for the assessment of analytical procedures,
in the elaboration and validation of analytical methods, and for educational
purposes.
Origin
and preparation of the material
A large
quantity of sediment was collected in 1998 from the intertidal mudflats of
the Tagus estuary (Portugal) for use as an intercomparison material. It was
deep-frozen, freeze-dried, ground and sieved. The sediment fraction of particle
size less than 150 µm was further homogenized by mixing in a stainless
steel rotating drum for two weeks. After checking for the homogeneity of the
sample material (see below), aliquots of about 35g were packed into cleaned
brown borosilicate glass bottles with Teflon lined screw caps and sealed in
plastic bags. A total of 530 bottles was produced.
Date of Release:
August 2000
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Unit Price:
130 €
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Unit Size:
35 g
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| Producer:
Marine Environment Laboratory (MEL) International Atomic Energy Agency B.P. No 800 MC-98012 Monaco |
Supplier:
Analytical Quality Control Services Agency's Laboratories, Seibersdorf A-2444 Seibersdorf, Austria |
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Reference Sheet:  IAEA-405(.pdf) |
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| * | Number
of accepted laboratory results which were used to calculate the recommended
or information values and their respective confidence intervals about
the mean value. |
| (R/I) | Classification assigned to the property value for Analyte (Recommended/Information) |
| # | As inorganic Hg |
The values listed
above were established on the basis of statistically and technically valid
results submitted by laboratories which had participated in an international
intercomparison exercise organized in 1998. The details concerning the criteria
for qualification as a recommended or information value can be found in the
report (IAEA/AL/127; IAEA/MEL/70), “Report on the World-wide Intercomparison
Exercise for the Determination of Trace Elements and Methylmercury in Estuarine
Sediment IAEA-405” [1]. This report is available free of charge upon
request.
Homogeneity
Extensive
homogeneity tests were carried out on this material in order to ensure its
suitability as an intercomparison sample. A preliminary test was performed
before final bottling and sample dispatch and did not detect any inhomogeneity
in the material. A final homogeneity test was conducted after completion of
the bottling of sample material. The between-bottle homogeneity was tested
by the determination of the concentration of some typical elements (Cu, Fe,
Mn, Zn) on sample intakes of 100 mg and 200 mg taken from 15 bottles which
were set aside at regular intervals during the whole period of bottling. The
within-bottle homogeneity was assessed by 15 replicate determinations on the
re-homogenized content of one bottle. A F-test at a significance level of
0.05 was performed for the different metals and did not reveal significant
differences between the within- and between-bottle variances for 100 mg intakes.
On the basis of these results, no inhomogeneities in the material were suspected.
It was concluded that the material is homogeneous at an analytical portion
of 100 mg and above for trace elements and, therefore, suitable for use as
an intercomparison sample [1].
Stability
of the material
The
stability of several trace metals was tested to determine the suitability
of this material as a candidate CRM. Five bottles of the IAEA-405 material
were stored in the dark at +20 °C, –20 °C and +60 °C, respectively,
over a period of 17 months (starting in September 1998) and the measurement
of total Hg, Cu, Fe, Mn and Zn was performed at regular intervals during the
storage period. On the basis of these results, it was concluded that no instability
of the material could be demonstrated [1].
Dry weight determination
The
average moisture content of the lyophilized sample after bottling, determined
by drying to a constant weight at 105°C, was found to be 2.5 %. Since
the moisture content can vary with the ambient humidity and temperature, it
was recommended that the water content of this material be determined in a
separate subsample (not used for analysis) by drying to a constant weight
(~24 hours) at 105°C just prior to analysis. Final results should always
be reported on a dry weight basis.
Instructions
for use
The
recommended minimum sample size for analysis is 100 mg. Analysts are reminded
to take appropriate precautions in order to avoid contaminating the remaining
material in the bottle. The bottle should be thoroughly mixed by shaking before
use and tightly resealed immediately after use. The material should be stored
in the dark and kept below 25 ºC.
References:
| [1] |
Last updated 30 March 2004
