## 3 Results and Discussion
### Optimization of the Safrole Extraction Method  
#### 3.3.1 Choosing the Fiber  
Choosing the fiber for safrole extraction by HS-SPME-GC/FID considered the area of the chromatographic response of each fiber exposed to the compound at 30 \({}^{\circ}\)C for 3 min of extraction time. The fibers coated with the different materials herein investigated presented distinct behavior, as statistically attested by [PERSON]'s test (_P_ < 0.05). The 50/30-\(\upmu\)m DVB/CAR/PDMS StableFlex fiber differed from both 85-\(\upmu\)m polyacrylate (PA), 100-\(\upmu\)m fused-silica PDMS and 7-\(\upmu\)m fused-silica PDMS ones (Figure 2). The 50/30-\(\upmu\)m DVB/CAR/PDMS StableFlex fiber differed from both 100-\(\upmu\)m fused-silica PDMS and 7-\(\upmu\)m fused-silica PDMS ones; whereas the 85-\(\upmu\)m fused-silica PA fiber only differed from the 7-\(\upmu\)m fused-silica PDMS (Figure 2). Ultimately, the fiber of choice was the 50/30-\(\upmu\)m StableFlex coated with DVB/CAR/PDMS, which delivered a response with a larger chromatographic area, indicating better safrole extraction. Polarity, molecular mass, and size of the analytes are criteria that also must be accounted for determining the most appropriate fiber for HS-SPME [42].  
[PERSON] et al. [45] assessed the performance of four fibers with different coatings for extracting volatile compounds from cherry wine--namely, 50/30-\(\upmu\)m DVB/CAR/PDMS StableFlex, 65-\(\upmu\)m PDMS/DVB, 75-\(\upmu\)m CAR/PDMS, and 100-\(\upmu\)m PDMS fibers. According to that study, the 50/30-\(\upmu\)m DVB/CAR/PDMS StableFlex fiber had the best performance for extracting 3-methyl-butanol, ethyl hexanoate, hexyl acetate, ethyl lactate, and 4-ethylguaiacol. This fiber also produced the best response for extracting aromatic compounds from cocoa by HS-SPME-GC/FID compared to fibers coated with PDMS, PDMS/DVB, and CAR/PDMS [50]. These findings support the results from the present study.  
Fibers coated with PDMS have long-term stability and performance regarding chromatography, extraction characteristics, and analyte recovery. In addition, they are durable and typically maintain good functioning for up to 100 analytical cycles. As these fibers  
Figure 2: Safrole extraction from cowpea beans by headspace solid-phase microextraction coupled to a gas chromatograph with a flame ionization detector using the fibers: (1) 50/30-\(\upmu\)m divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) StableFlex, (2) 85-\(\upmu\)m polyacrylate (PA), (3) 100-\(\upmu\)m PDMS, and (4) 7-\(\upmu\)m PDMS. Sample mass: 5.0 g; extraction: 30 \({}^{\circ}\)C for 3 min (\(n\) = 3). The same letters are not significantly different by [PERSON]’s test (_p_ < 0.05).  
are non-polar, the manufacturers suggest them for extracting non-polar analytes, such as aromatic and volatile compounds from EOs. As for mixed fibers, whose coating contains DVB or CAR, their retention capacity is raised due to a mutual potentiating effect on the extraction and distribution of the stationary phase. Double-coated DVB/CAR/PDMS fibers have a layer of PDMS-DVB over another of CAR-PDMS. They are also recommended for flavor and odor extraction (either volatile or semi-volatile) in foodstuff [50].