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about 70
°
C, and analyzed. The method was tested by application to NCS ZC
78005“mussel tissue”with good precision and accuracy. Detection limits were
found to be 0.3-5
μ
g/g dried mass. For muscle tissue, the concentration of 12
elements (P, S, K, Ca, Mn, Fe, Cu, Zn, Se, Br, Rb, Sr) for fishes of the exposed
site was only slightly increased (a factor of about 1.2). All elements were far
below the critical limits given by the Food and Agricultural Organization
(FAO) of the United Nations and do not constitute any health risk for
consumers. However, for liver tissue, the concentration of several elements
(P, S, K, Ca, Mn, Fe, Cu, Zn) was significantly higher for fishes of the polluted
site (a factor of about two). Obviously, these elements accumulate in fish liver.
Airborne pollutants emitted from the power plant are probably the reason for
the elevated concentration. Analyses of airborne particulate matter from both
sites corroborated this result.
Total reflection XRF can also be used to study bioaccumulation of particular
nanoparticles in vital organs [54]. For that purpose, nanorods of gold (40 nm
×
10 nm) were suspended in saline at a dose of 4
μ
g/g, and 200
μ
l of this
suspension was injected in mice. Tissue sections were taken from main organs,
such as liver, spleen, brain, and lung, after a period of 0 h, 1 h, 1 day, 1 week, and
1 month, and digested by aqua regia and H
2
O
2
. Urine was sampled in addition.
With As as internal standard, TXRF analysis was carried out by means of the
Au-L
α
peak. Tests of bovine liver CRM (certified reference material) showed a
recovery rate of 99.7% and a detection limit of 110 ppb. It could be shown that
liver and spleen accumulated gold particles significantly within one day while
brain, lung, and urine did not take up the nanoparticles. Further studies of gold
and silver nanoparticles are described in Section 5.4.8.3.
Different kinds of pollen build a further biomaterial sensitive to environ-
mental pollution. Their use as bioindicators was tested by Pepponi
etal
. [56].
Pollen of the Common Hazel (
Corylusavellana
) was sampled at different sites in
Italy with a different anthropogenic impact. The pollen was collected below
bushes from ripe aglets and sieved through a mesh with 50
μ
m pore size. About
30 mg pollen was suspended in 1 ml of ultrapure water spiked with gallium as
internal standard and stirred. Further aliquots of some 30 mg pollen were
digested with concentrated HNO
3
in a microwave oven at 200
°
C and 1.7 MPa
for 20 min. For TXRF analysis, 5
μ
l of the suspension and of the solution was
deposited on clean quartz-glass carriers. A Mo/W double anode tube was used
for excitation. The measuring time was set to 400 s. Detection limits for iron and
heavier elements were of the order of 0.3
μ
g/g. Seventeen elements between
aluminum and lead could be determined with concentrations of several mg/g (
‰
)
for minor elements and of 0.3 to 1
μ
g/g (ppm) for trace elements. The results of
suspensions are comparable to those of solutions; however, the reproducibility
and representativeness of the results argue in favor of the digestion.
In a further study, bee honey sampled from floral nectars in the central west
of Argentina was characterized by Vázquez
etal
. [47]. The authors emphasize
that honey is an environmental indicator of toxic metal contamination because
it reflects more than one million interactions of bees per hive with flowers per
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