## 3 Results and Discussion
### Extraction Technique Pre-Optimization and Comparison
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Extraction Technique** & **LLE** & **SPE** & **SPME** & **SBSE** & **HSSE** \\ \hline Detected compounds (/24) & 23 & 22 & 21 & 22 & 22 \\ \hline Handling time * & 3 h & 1 h & 0.2 h & 0.2 h \\ \hline Sample amount & 50 mL & 13 mL & 3 mL & 3 mL \\ \hline Solvent amount & 200 mL & 10 mL & - & - \\ \hline Quantitative analysis & +++ & +++ & + & + \\ \hline Automation & Low & High & High & Moderate \\ \hline Cost per analysis & Low & Low & Moderate & Moderate \\ \hline Cost of instrumentation & Low & High & Moderate & High \\ \hline \hline \end{tabular}
* in this study, all extractions were carried out manually. “++”: 20% \(>x\geq\) 1%; “+”: 0.1% \(>x\geq\) 0.01%. “-”: not relevant.  
\end{table} 
Table 2: Results obtained by applying different extraction techniques to the model mixture. However, SPME offers considerable advantages to micro-distileries. In manual mode, this method is easy to operate and only requires basic and inexpensive consumables. Full automation is possible at a relatively affordable price compared to on-line SPE and operating parameters can be effectively transposed from manual to automated mode without major adjustment. In that case, a very low handling time is necessary. Moreover, SPME fibers can be thermally desorbed directly in the GC injector and do not require specific equipment. The SBSE and HSSE extraction methods gave slightly better results than SPME with 22 detected in both immersion and headspace modes. This can be explained by the fact that stir bars have a much larger coating volume than SPME fibers. Neither with SBSE nor HSSE was decanoic acid detected despite its relatively high concentration. This might be a consequence of its low affinity with the apolar poly(dimethylsiloxane) stir bar in addition to the poor response of fatty acids with apolar columns. In contrast to SPME, stir bar extractions have to be carried out manually [36] and require a specific equipment for thermal desorption and, therefore, a supplementary cost. Even though LLE appears to be the most efficient technique for the extraction of distilled spirits in terms of detected compounds, SPE, SPME and SBSE/HSSE present some advantages. To identify the most efficient technique, two situations can be envisaged. If a quantitative analysis is desired, LLE and SPE are the most appropriate methods. The results of this study showed that LLE enabled to detect more compounds of the model mixture. The main advantage of SPE is its possible full automation, but the cost of this equipment and the need for skilled operators might be a limitation of this technique for micro-distileries. Even if quantitative analyses bring valuable information about the flavor profile of distilled spirits, they are not always necessary. In particular, a large quantity of trials can be done by micro-distileries while developing new products. In that situation, qualitative analyses bringing quick results at an affordable price in of high interest. This study showed that SPME offers the best compromise in terms of efficiency, cost, solvent and sample consumption, and environmental impact. Consequently, SPME was selected for further optimization. Using this method, the best results were obtain using a DVB/CAR/PDMS fiber and addition of NaCl. The influences of extraction time and temperature on peak area were then studied.