2.2.1. SPME procedure
Crushed dark chocolate with hazelnuts samples (0.1 g), along with
1 mL of distilled water and a micro-stirring bar were placed in a 10 mL
glass serum vial sealed with an aluminum crimp cap provided with a
needle-pierceable polytetrafluroethylene/silicone septum. Solidphase
microextraction (SPME) was performed with a 75-mm
Carboxen/Polydimethylsiloxane (PDMS) fibre mounted to a SPME
manual holder assembly (Supelco, Bellefonte, USA). The sample vial
was placed in a 60 °C water bath and stirred at high speed. After
allowing 10 min for the sample to equilibrate at 60 °C, the needle of
the SPME device was inserted into the vial through the septum, and
the plunger of the SPME apparatus was pushed down to expose the
Carboxen/PDMS fibre to the vial head space. After 10 min of exposure
time with constant stirring, the fibre was retracted into the needle
assembly, removed from the vial, and transferred to the injection port
of the GC unit.