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ancient bracelets made of silver and gold [212]. The bracelets were investigated
in tombs at El-Mahasna, Egypt, stem from the fourth millennium BC, and are
the only gold artifacts known for the Naqada I period. After sampling the
loaded cotton buds were placed in clean beakers and transported to the
laboratory. TXRF analyses were performed within a few minutes and semi-
quantitative results were obtained by relative sensitivities. The main constitu-
ents were silver (430-990 mg/g) and gold (
<
300 mg/g), determined with an
accuracy of about 5%. Secondary components were iron, copper, and zinc. It
could be concluded that most of the beads probably consist of a rather strange
alloy, that is, natural aurian silver alloy. Such beads could be smelted from
naturally occurring ores of Egyptian or Nubian“gold”mines.
Unfortunately, this method of sampling cannot be applied to hard materials,
such as alloys of stainless steel and alloys of refractory metals. For metallic
alloys with phases of different hardness, the troublesome problem of prefer-
ential abrasion arises. Consequently, bronze and brass can only be sampled in
the mentioned method for a first qualitative survey. Quantitative results show a
surplus of soft lead components, which are preferably rubbed off. As shown by
the analysis of relevant standard reference materials, repeatability and accu-
racy get worse and the result for the soft components or phases can be incorrect
by a factor of
>
2.
Steel alloys used for the core components in nuclear reactors were investi-
gated after dissolution by Pepponi
etal
. [213]. Several elements, including rare
earth elements, can cause a much higher activity than the main components of
steel alloys, such as iron or titanium. In order to limit nuclear radioactive waste,
only small amounts of the material were taken and dissolved in concentrated
acids. The main components, iron and titanium, were separated first by means
of ion-exchange chromatography. Rubidium and zirconium were added as
internal standards, and 2
μ
l droplets of the acidic solution with 20
μ
g steel were
deposited on a reflector for TXRF analysis. In order to excite the K shell of
niobium, photon energies of 19.7 keV were used. For the rare earth elements,
the white synchrotron radiation with high photon energies was applied. A side-
looking geometry was chosen for detection and several alloy samples were
investigated. The detection limit for niobium was about 50 ng/g, for rare earth
elements, for example, terbium, 500 ng/g. Similar values were also found for
simple EDXRF when larger droplets of 25
μ
l were deposited on 150 nm thick
AP1
TM
films.
5.5.3TextileFibersandGlassSplinters
A special method has been developed for the analytical characterization of
single textile fibers [214]. A variety of 35 different types and models of
uncolored textile fibers (e.g., polyester, viscose, or wool) was first analyzed
in order to get the respective element patterns.
A sample of 500
μ
g of every kind of fiber was placed on a carrier; then, 20
μ
l
of nitric acid with 20 ng of an internal standard (gallium) were added and dried
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