A headspace solid-phase microextraction (HS-SPME) procedure based on five commercialised fibres (85 μm polyacrylate - PA, 100 μm polydimethylsiloxane - PDMS, 65 μm polydimethylsiloxane/divinylbenzene - PDMS/DVB, 70 μm carbowax/divinylbenzene - CW/DVB and 85 μm carboxen/polydimethylsiloxane -