Method validation for determination of metals in Vitis labrusca L. grapevine leaf extracts by inductively coupled plasma mass spectrometry (ICP-MS).

Vitis labrusca L. is the main species used for wine and juice production in Brazil. The grapevine leaves can be used both as functional foods and as cheapest sources for the extraction of phenolic compounds. Besides the antioxidant activity, grapevine leaves exhibited significant anti-inflammatory activity. Therefore, the aim of this study was to develop and validate an analytical methodology to determine the metals selenium (96Se), chromium (53Cr), nickel (62Ni), cadmium (111Cd) and lead (206Pb) in 30 samples of grapevine leaf extracts (Vitis labrusca, Bordo cultivar) using inductively coupled plasma mass spectrometry (ICP-MS). To obtain the grapevine leaf extracts the samples were milled, weighed and digested in microwave oven with nitric acid. The method showed linearity, precision, accuracy and limits of quantification and detection acceptable for INMETRO protocol validation of analytical methods. Therefore, the method using ICP-MS was developed and validated to determine metals concentrations in grapevine leaves of Vitis labrusca L. and the proposed method could be applied in routine analytical laboratory.

Analysis of chemosensory markers in cigarette smoke from different tobacco varieties by GC×GC-TOFMS and chemometrics.

Commercial cigarettes are made from a blend of different tobacco varieties, which in turn are the results of different agronomic practices and post-harvest curing processes. The highly complex mixture of smoke compounds reflects each tobacco variety and the levels of sensory-relevant markers. Therefore, the aim of this work was to identify potential relevant chemosensory markers in the mainstream smoke of four main types of commercial tobaccos and establish any possible relationship between them and the tobacco growing/curing practices. The tobacco samples were segregated into four segments: (1) three curing stages of flue-cured Virginia, (2) three curing stages of air-cured Burley, (3) three geo-regions of sun-cured Oriental and (4) three different process applied to tobacco. One hundred and twenty cigarettes (10 batches per flavour category) were produced and smoked under standard machine-smoking protocols. The mainstream smoke samples collected were extracted and analysed by GC × GC TOFMS. The processed data was analysed by partial least square discriminant analysis (PLS-DA) and the selectivity ratio was used to identify key chemosensory markers responsible for the four segments. All models had sensitivity and specificity equal to unity. Flue-cured Virginia (193 markers) and air-cured Burley (184 markers) showed a similar trend for O-heterocycles markers in the lighter leaf colours and N-heterocycles in the darker leaf colours post-processing, but they had compounds of different flavour descriptions, e. g. sweet and nutty. The three geo-regions of sun-cured Oriental (290 markers) also presented O-heterocycles markers in correlation with leaf sugar contents in addition of sucrose esters markers. The three unusually processed tobacco generated many chemical markers (436 markers), some derived from the so-called Cavendish fermentation process with sweet, spicy and peppery notes, whereas the dark fermented air-cured tobacco presented similar descriptors as air-cured Burley. In addition, some polycyclic aromatic hydrocarbons (PAH) were detected as markers from the fire-curing process. The PLS-DA with selectivity ratio evidenced total of 1098 chemosensory markers in cigarette smoke, in which 173 were tentatively identified.