Table 1 shows the optimum factor values affecting
the CUES for copper extraction in mussel
samples.
Two sample variables that can affect the acid
extraction process have been studied: the mussel
particle size and the amount of sample. Using the
optimum CUES conditions, particle sizes of -30
and 30–100 mm were tested. The results obtained
indicate that this variable does not affect the
extraction process. This can be explained by the
high energy supplied by the ultrasound energy
(frequency of 40 kHz), which increases the contact
between the sample and the leaching solution. As
an amount of 10 mg was used to optimize the
CUES system and optimum results were obtained,
we suppose that smaller quantities would also be
suitable. However, it is important to know the
maximum amount of sample that is quantitatively
leached in order to increase the sensitivity of the
method. Sample amounts of 20–60 mg were studied.
Results demonstrated that sample amounts
greater than 30 mg produce high pressure in the
CUES. Therefore, the maximum sample amount
used is 30 mg.