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The use of SPME fibers coated with porous polymer solid phases for quantitative purposes is limited due to effects such as interanalyte displacement and competitive adsorption. For air analysis, these problems can be averted by employing short exposure times to air samples flowing around the fiber. In these conditions, a simple mathematical model allows quantification without the need of calibration curves. This work describes two portable dynamic air sampling (PDAS) devices designed for application of this approach to nonequilibrium SPME sampling and determination of airborne volatile organic compounds (VOCs). The use of a PDAS device resulted in greater adsorbed VOC mass compared to the conventional SPME extraction in static air for qualitative screening of live plant aromas and contaminants in indoor air. For all studied air samples, an increase in the number of detected compounds and sensitivity was also observed. Quantification of aromatic VOCs in indoor air was also carried out using this approach and the PDAS/SPME device. Measured VOC concentrations were in low parts-per-billion by volume range using only 30-s SPME fiber exposure and were comparable to those obtained with a standard NIOSH method 1501. The use of PDAS/SPME devices reduced the total air sampling and analysis time by several orders of magnitude compared to the NIOSH 1501 method.

Kohonen Neural Network maps were used for exploratory analysis of Brazilian Pilsner beers. The input data consisted of the peak areas of the volatile profile compounds of samples obtained after headspace solid phase microextraction coupled to gas chromatography. The chromatographic peaks were identified as originating from compounds such as alcohols, esters, organic acids, phenolic compounds, ketone and others typically found in the headspace of such samples. Analysis of the Kohonen maps showed that the 20 different brands of beer could be grouped into six sets, with three of these sets having only one sample, according to the composition of their volatile fractions. The volatile species associated with the similarities and differences between each sample group were tentatively identified by mass spectrometry and their contributions to the grouping are discussed.