2.4. Sample preparation for solid-phase microextraction (SPME)
50% w/w dilution with water was made for all honey samples. Diluted honey (1 mL) and 1 g of NaCl were measured into a 20-mL SPME vial with a glass covered stirrer. Blossoms were placed into 20-mL SPME vial immediately after harvesting depending on the size of the blossoms, covering approximately 1 cm above the bottom of the vial. In order to apply the same headspace volume to all the samples and to avoid cutting the flowers, volume was used instead of weight for the samples. Two replications of each sample were done for GC–O for each assessor (three assessors in total) and one sample for GC–MS. All vials were capped with PTFE-silicon septa and placed in an autosampler tray at room temperature. Samples were brought one-by-one into magnetic stirring chamber for volatile extraction using a method described in the next section. Magnetic stirring was used for honey samples but not for blossoms. After the extraction process the fibre was injected into the GC inlet for desorption for 10 min (either GC–MS (TOF) or GC–O), followed by the oven temperature program described in the next section.