## 2 Results and Discussion
### Validation and Comparison of Both Methodologies

Table 1: LODs, LOQs, linear dynamic ranges, slopes (\(a\)), \(x\)-axis interceptions (\(b\)) and determination coefficients (\(r^{2}\)) values from the calibration plots obtained for the five monoterepnoids by HS-SPME(PDMS/DVB) and HS-BA\(\mu\)E(R), followed by GC-MS analysis, under optimized experimental conditions. methodologies. The LLOQ corresponds to the lowest concentration level, which might be quantified under both precision and accuracy criteria (RSD and %RE \(\leq\) 20 %) and normally corresponds to the first value of the calibration plots [13; 14]. As noted in Table 1, LLOQs values of 0.5 ug L\({}^{-1}\) (HS-SPME(PDMS/DVB)) and 20 mg L\({}^{-1}\) (HS-BA\(\mu\)E(R)) were achieved for the five BVOCs, respectively. Moreover, the slopes from the regression plots obtained through the HS-SPME(PDMS/DVB) methodology (26.193 \(\leq a\leq 75.885\)) are significantly higher than the ones obtained by HS-BA\(\mu\)E(R) (4.508 \(\leq a\leq 7.184\)); we can establish that the former presents a much higher sensitivity, using the analytical configuration conditions reported. The accuracy and precision of both methodologies were evaluated through the determination of the percentage of the relative error (%RE) and RSD values, respectively, through intra-day (\(n=6\)) and inter-day (\(n=6\), over 3 consecutive days) assays. In both repeatability assessments, four different spiking levels were evaluated, including the LLOQ and a low, medium and higher value. For the HS-SPME(PDMS/DVB) methodology, levels of 20, 100, 400 and 700 ng were selected, whereas for the HS-BA\(\mu\)E(R) approach, the levels were 100, 200, 300 and 500 ng. Through both intra-day and inter-day studies, the analytical methodologies exhibited good results at the LLOQ (RSD and %RE \(\leq\) 19.9%) and other spiking levels (RSD and %RE \(\leq\) 14.2%), which indicates a good fit for the assessment of the five selected BVOCs in the HS sampling mode. In general, we can state that both analytical methodologies present a very similar effectiveness for BVOCs analysis, since excellent reproducibility is achieved in monitoring the five monoterpenoids under the HS sampling mode. If we assume that HS-SPME is a well-established standard or reference method, whereas HS-BA\(\mu\)E is a novel proposed approach for BVOCs analysis, we can claim that both methodologies are equivalent, providing similar and proportional responses. Figure 5 shows the comparison data obtained from the HS-BA\(\mu\)E(R) response against the HS-SPME(PDMS/DVB) response for the five monoterpenoids, under optimized experimental conditions, where it is verified that the latter methodology presents an average order of magnitude between five (1,8-cineole) and ten (\(\alpha\)-pinene) times higher, which is reflected by the slopes founded. It can also be observed that the different responses obtained for each monoterpen depend on the best interaction and affinity with the sorbent phases used, as well as the synergism involved simultaneously among the target compounds involved. Moreover, if we assume that both analytical technologies can be routinely used and are in line with the GAC principles, or that the inherent aspects are negligible, we can state that the HS-BA\(\mu\)E methodology is a much more cost-effective and comprehensive technique, since it can be easily interfaced with different instrumental systems. On the other hand, from a strictly practical point of view, the HS-SPME methodology, based on TD, seems to be more user-friendly, whereas HS-BA\(\mu\)E, based on LD, offers the advantage of being able to carry out a reanalysis of the sampled matrices, which is a very important issue whenever the repetition and data confirmation are mandatory.