###### Abstract  
In this work, a new analytical approach is proposed for monitoring biogenic volatile organic compounds (BVOCs) by combining headspace bar adsorptive microextraction (HS-BAuE) with gas chromatography-mass spectrometry (GC-MS). The HS-BAuE methodology was developed, optimized, validated and applied for the analysis of BVOCs emitted from two tree species (_Eucalyptus globulus_ Labill. and _Pinus pinster_ Aiton) and compared with headspace solid phase microextraction (HS-SPME), commonly accepted as a reference technique. To achieve optimum experimental conditions, numerous assays were carried out by both methodologies, studying the release of the five major monoterapenoids (\(\alpha\)-pinene, \(\beta\)-pinene, myrcene, limonene and 1,8-cineole) from the leaves of the tree species, whereas the maximum selectivity and efficiency were obtained using an activated carbon and PDMS/DVB fiber as sorbent phases for HS-BAuE and HS-SPME, respectively. Under optimized experimental conditions, both methodologies showed similar profiling and proportional responses, although the latter present a higher sensitivity in the analytical configuration used. For the five monoterapenoids studied, acceptable detection limits (LODs = 5.0 uE\({}^{-1}\)) and suitable linear dynamic ranges (20.0-100.0 mg L\({}^{-1}\); \(r^{2}\geq\) 0.9959) were achieved, and intra- and inter-day studies proved that both methodologies exhibited good results (RSD and \(\%\)RE \(\leq\) 19.9%), which indicates a good fit for the assessment of BVOCs by the HS-BAuE/GC-MS methodology. Assays performed on sampled leaves by both optimized and validated methodologies showed high levels of the five major BVOCs released from _E. globulus_ Labill. (10.2 \(\pm\) 1.3 to 7828.0 \(\pm\) 40.0 ug g\({}^{-1}\)) and _P pinster_ Aiton (9.2 \(\pm\) 1.4 to 3503.8 \(\pm\) 396.3 ug g\({}^{-1}\)), which might act as potential fuel during forest fire's propagation, particularly under extreme atmospheric conditions. This is the first time that BAuE technology was applied in the HS sampling mode, and, in addition to other advantages, it has proven to be an effective and promising analytical alternative for monitoring VOCs, given its great simplicity, easy handling and low cost. BVOCs; HS-BAuE; HS-SPME; GC-MS; _Eucalyptus globulus_ Labill. ; _Pinus pinster_ Aiton 2023281179. 282023281179. 282023281179. 282023281179. 282023281179. 282023281179. 282023281179. 282023281179. 282023281179. 282023281179. 282023281179. 282023281179. 282023281179. 282023281179. 28202328179. 282023 lead to outbreaks of long-distance fires. As these BVOCs have densities lower than that of air, it has been suggested that the emitted fraction, composed mainly of terpenoids, might accumulate at lower altitudes and under vegetation [1]. Thus, in the presence of certain weather conditions and other combustion gases, the accumulated terpenoids can cause a rapid and intense ignition, increasing the flame height and accelerating the fire spread [2]. Therefore, it is of utmost importance to study the type, number and chemical characteristics of the BVOCs emitted from the main tree species, particularly the most abundant, which may have a greater influence on forest fires in extreme conditions. Due to the physicochemical properties of BVOCs, state-of-the-art analytical methodologies for monitoring include an enrichment step prior to gas chromatography coupled with mass spectrometry (GC-MS). In addition to active sampling techniques (e.g., purge and trap), passive sampling approaches have been proven to be much easier to operate and are in compliance with the green analytical chemistry (GAC) principles [3]. Modern passive sorption-based techniques, such as solid-phase microextraction (SPME), are the most successful enrichment techniques enabling the direct microextraction of the main volatile and semi-volatile compounds from several types of matrices through the headspace (HS) sampling mode while enhancing the very high selectivity and sensitivity.