Flow injection determination of copper in mussels by flame atomic absorption spectrometry after on-line continuous ultrasound-assisted extraction

Copper was extracted on-line from solid mussel samples by a simple and rapid continuous ultrasound-assisted extraction system (CUES). The CUES is connected to a flow injection manifold, which permits the on-line flame atomic absorption spectrometric determination of copper. The manifold is simple and the copper signal was obtained for a volume of 250 μl of acid leachate injected into an ultrapure water carrier stream. An experimental design was used for the optimization of the continuous leaching procedure. Compared to off-line ultrasonic-assisted extraction methods, sonication time is reduced by factors of 6–12, the leaching takes place at room temperature (20 °C), and the analysis time is reduced because centrifugation was not necessary to separate the liquid phase. The method allowed a total sampling frequency of 11 samples h−1, with a relative standard deviation for the complete procedure of 2.7% (for a sample containing 2.0 μg g−1 copper (wet mass, n=11). The limit of detection was 0.06 μg g−1 (wet mass) for 30 mg of sample. The analytical procedure was verified for a reference standard material (TORT-1). The analytical procedure was applied to mussel samples from Galicia (Spain).