Plasmaquant 110 (Carl Zeiss Jena GmbH) ICP spectrometers were
used to measure the concentrations of the Þfteen trace elements of
seventeen samples at 17 di¤erent wavelengths. The details of the
analytical program and the wavelengths used can be found in Table
2. To increase the reliability of the analytical results, each sample
was preprocessed using di¤erent methods (i.e., direct method, decomposition
method, and standard addition method) as shown in
Table 1 and was measured by both ICP-OES instruments. For
samples in a complex matrix the standard addition method is preferred
[50]. In the case of the direct method, standard solutions
containing ethanol and di¤erent amounts of the elements to be
determined were used for calibration. In order to be able to compensate
for intensity di¤erences caused by viscosity inßuences of the
organic components during sample nebulization, the organic compounds
of the wine, in particular the alcohol, must be removed from
the samples. The wine samples were therefore decomposed using
perhydrol. This method, however, is very time-consuming. For more
details of these methods, see [50]. Finally, 170 samples were utilized
for both ICP-OES measurements and data analysis because each
original wine sample was measured 10 times (see Table