Abstract The chemical composition of volatile compounds from Spondias tuberosa fruits were investigated at four days of maturity and from two accessions. These days were characterized through the compounds’ profiles obtained by extracting volatiles using solid-phase microextraction in headspace mode (HS-SPME) and analyzed by gas-chromatography coupled to mass spectrometry (GC-MS). A total of 27 and 22 compounds were identified from the EPAMIG-C02 and EPAMIG-C10 accessions, respectively. The main chemical class in both accessions were the esters, aldehyde, alcohols and terpenes. The study revealed a tendency to increase the ester content and decrease the aldehyde and terpene content during four days of post-harvest ripening for the two accessions. This behavior may be monitored by five key compounds such as two esters (ethyl butanoate and ethyl hexanoate) and three aldehydes (hex-2-enal, nonanal and dec-2-enal). These compounds may be used as markers for the maturity stage for the two accessions. The Principal Components Analysis (PCA) accumulated 73.85% of the total variance in principal components 1 and 2 and showed that it is possible to differentiate the fruit ripening stages through these compounds.

Abstract In this study, the volatile organic compounds from Spondias tuberosa fruits of 16 accessions with different origins were extracted by solid-phase microextraction in headspace mode (HS-SPME) and analyzed by gas-chromatography coupled to mass spectrometry (GC-MS). The volatile compounds present in the fruit from the 16 accessions were identified and submitted to multivariate analysis, with the main volatile compounds identified (from a total of 25) being: ethyl butanoate, α-pinene, myrcene/ethyl caproate, limonene, ocimene isomers, linalool/nonanal and p-menth-1-en-4-ol. The major chemical classes were terpenes (about 7-72%) and esters (about 14-72%). The relative chromatographic areas of the volatile compounds were used in Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA), which accumulated 67.69% of the explained variance. The compounds classified as esters and terpenes were the main compounds responsible for forming distinct groups. The PC1 and PC2 enabled distinguishing the percentage of compounds responsible for grouping in the PCA quadrants and the HCA shows the grouping of these compounds.

RESUMO AVALIAÇÃO DA BIODISPONIBILIDADE DE METAIS PESADOS APÓS VERMICOMPOSTAGEM EM PRESENÇA DE LIXO ELETRÔNICO Os metais pesados presentes no lixo eletrônico, descartado de forma inadequada, podem se tornar biodisponíveis após a vermicompostagem, representando risco ao ambiente. Foram realizados experimentos de vermicompostagem em pequena escala na presença de placas de circuito impresso (PCI) para investigar a migração de metais pesados (Cu, Pb, Zn, Ni e Sn) para o composto obtido, assim como a mobilidade e biodisponibilidade desses metais. Os resultados evidenciaram elevados teores totais de Pb, Sn e Cu nas amostras de esterco com resíduo eletrônico (ERE) e vegetais com resíduo eletrônico (VRE). Levando-se em consideração os teores iniciais dos metais nas PCIs e as concentrações dos mesmos no composto obtido, a ordem de migração desses metais para as amostras ERE e VRE foi Sn (23,1 %)>Pb (18,4 %)>Ni (4,63 %)>Zn (0,46 %)>Cu (0,14 %) e Sn (24,3 %)>Pb (23,6 %)>Ni (11,33 %)>Zn (1,76 %)>Cu (0,60 %), respectivamente. A avaliação da mobilidade e biodisponibilidade dos metais no composto foi realizada mediante a extração sequencial em três etapas, sendo F1 a fração trocável, F2 a fração orgânica e F3 a fração residual. O fator de biodisponibilidade (FB) foi obtido pela razão entre a soma das frações F1 e F2 pela soma total das frações (F1 + F2 + F3). O maior valor do FB (0,92) foi encontrado para o Pb, metal pesado considerado de maior preocupação ambiental neste estudo, o que indica alta mobilidade desse metal, podendo tornar-se biodisponível.

ABSTRACT Heavy metals contained in electronic waste, if discarded improperly, can become bioavailable after vermicomposting, posing a risk to the environment. Small-scale vermicomposting experiments were carried out with printed circuit boards (PCBs) to investigate the migration of heavy metals (Cu, Pb, Zn, Ni, and Sn) to the final compost, as well as the mobility and bioavailability of these metals. High total levels of Pb, Sn and Cu in samples of manure with electronic waste (MEW) and vegetables with electronic waste (VEW) were detected. Based on the initial metal levels in the PCBs and their concentration in the resulting compost, the order of migration of these metals to the MEW and VEW samples was Sn (23.1 %)>Pb (18.4 %)>Ni (4.63 %)>Zn (0.46 %)>Cu (0.14 %) and Sn (24.3 %)>Pb (23.6 %)>Ni (11.33 %)>Zn (1.76 %)>Cu (0.60 %), respectively. Mobility and bioavailability of these metals in the compost were evaluated by three-stage sequential extraction, where F1 was the exchangeable fraction, F2 the organic fraction and F3 the residual fraction. The bioavailability factor (BF) was calculated by the ratio of the sum of fractions F1 and F2 divided by the total sum of the fractions (F1 + F2 + F3). The highest bioavailability factor (BF = 0.92) was found for Pb, the heavy metal considered the greatest environmental concern in this study, indicating the high mobility and the possibility of becoming bioavailable of this metal.

Multivariate models were developed using Artificial Neural Network (ANN) and Least Square - Support Vector Machines (LS-SVM) for estimating lignin siringyl/guaiacyl ratio and the contents of cellulose, hemicelluloses and lignin in eucalyptus wood by pyrolysis associated to gaseous chromatography and mass spectrometry (Py-GC/MS). The results obtained by two calibration methods were in agreement with those of reference methods. However a comparison indicated that the LS-SVM model presented better predictive capacity for the cellulose and lignin contents, while the ANN model presented was more adequate for estimating the hemicelluloses content and lignin siringyl/guaiacyl ratio.