Chemical composition and antimicrobial activity of the essential oil from Aeolanthus suaveolens Mart. ex Spreng

The essential oils from leaves (sample A) and flowers (sample B) of Aeolanthus suaveolens Mart. ex Spreng were obtained by hydrodistillation and analyzed by GC, GC-MS, and chiral phase gas chromatography (CPGC). Six compounds have been identified from the essential oils, representing ca 94.3 and 93% of the oils corresponding to samples A and B, respectively. The major constituents of samples A and B essential oils were respectively, linalool (34.2%/34.9%), (-)-massoialactone (25.9%/17.0%) and (E)-beta-farnesene (25.4%/29.1%). The enantiomeric distribution of the monoterpene linalool was established by analysis on heptakis- (6-O-methyl-2,3-di-O-pentyl)-beta-cyclodextrin capillary column. The antimicrobial activity of the essential oil from leaves and isolated compounds was also evaluated.

Determinação de herbicidas usados no cultivo de arroz irrigado na região sul do estado de Santa Catarina através da SPME-GC-ECD

Evaluation of the pollution by the herbicides alachlor, propanil and atrazine in water samples from four rivers in the cities of Turvo and Meleiro, south of Santa Catarina State, was made using the SPME-GC-ECD method. The proposed method was optimized and validated. The correlation coefficients were higher than 0.997 and linear ranges of the analytical curves were 0.1-4; 0.1-2.5 and 0.1-5 µg L-1 for atrazine, alachlor and propanil, respectively. The herbicides were quantified by GC-ECD and identified by GC-MS. Both of the selected rivers presented contamination by at least one of the studied herbicides.

A pirólise como técnica analítica

In this paper historical aspects of analytical pyrolysis, the equipment used, the fundamentals and the mechanisms of pyrolysis of different polymeric materials are discussed. The latest work on analytical pyrolysis applied to various types of synthetic and natural samples is reviewed. Current applications of this technique that are discussed include identification of microorganisms, analysis of trace compounds by forensic laboratories, investigation of food and agricultural products, study of the chemical composition of wood, authentication and conservation of artworks, and the study of environmental and geochemical samples.

Chemical composition and antimicrobial activity of the essential oil of Hyptis pectinata (l.) Poit.

Essential oil was extracted from leaves of Hyptis pectinata using hydrodistillation, and its composition determined using GC-FID and GC-MS. Chemical analysis showed that there was a predominance of sesquiterpenes, of which β-caryophyllene (18.34%), caryophyllene oxide (18.00%) and calamusenone (24.68%) were measured for the first time in the genus Hyptis. Twenty-one compounds were identified, and calamusenone was isolated using preparative thin layer chromatography with a silica gel plate (60 PF254). The minimal inhibitory concentration (MIC) and minimal microbicidal concentration (MMC) were determined for various pathogenic microorganisms. H. pectinata oil was most effective against Gram (+) bacteria and yeasts.

Comparação de técnicas de determinação de ésteres em cachaça

An analytical comparison of three different techniques for quantitative profile of esters in cachaça is reported. The Ministério da Agricultura Pecuária e Abastecimento (MAPA) recommends the use of GC/FID or volumetry. Despite being laborious and lacking in chemical speciation, the volumetric technique for total ester content shows to be appropriate, reproducible, and accurate for the analysis of cachaça. However, the GC/FID suggested by MAPA, considering only ethyl acetate, shows inaccuracy, underestimating the total ester content by a median factor of 72%, mainly due to the absence of ethyl lactate analysis. On the other hand, the GC/MS technique that comprises the analysis and speciation of nine esters, including ethyl lactate, proved to be reproducible, simple, fast and accurate for the analysis of total ester content in cachaça. Thus, the total ester content results obtained using GC/FID must be considered with precaution.

Composição química volátil, em diferentes estádios de maturação, de manga 'Tommy Atkins' produzida no Vale do São Francisco

The effect of the maturation stages on the volatile chemical composition of mango fruit cv. Tommy Atkins, cultivated in São Francisco Valley, was investigated using SPME. GC/MS and GC-FID analysis allowed the identification of 32 compounds, consisting mainly of monoterpenes. δ-3-Carene was the major component in all the stages, while α-terpinolene, trans-β-caryophyllene e α-pinene succeded each other as the second most abundant constituent, during the ripening. The aroma of the ripe fruit was characterized by presence of short-chain ethyl esters (C2-C6), whereas the green mango contained the highest concentration of δ-3-carene. Furthermore, some terpenes were detected exclusively at one of the stages.

Otimização e validação intralaboratorial de método para análise de resíduos de cloranfenicol em leite caprino por cromatografia gasosa com detecção por captura de elétrons (CG/DCE)

The presence of chloramphenicol residues in goat milk can cause toxic effects in the population. The present work consists of the optimization and validation of analytical methodology for determination of chloramphenicol residues in goat milk by GC/ECD. The extraction was made with ethyl acetate and the clean-up with SPE-C18. The identification was made by comparison of retention time and GC/MS, and the quantification by external standard. The method was selective, linearity (0.998), precise (5.8-13.4%), exact (69.87-73.71%) and robust. The LOD and LOQ of method were 0.030 and 0.10 μg/kg, respectively. The method was efficiently for analysis of chloramphenicol in goat milk.

Estudo da eficiência de degradação de tetracloreto de carbono por plasma térmico e caracterização dos produtos formados

Decomposition of carbon tetrachloride in a DC thermal plasma reactor was investigated in argon atmosphere. The operational parameters such as plasma torch power and argon flow rate versus CCl4 conversion were examined. The CCl4 net degradation was determined by GC-FID, the chlorine produced was quantified by iodometric titration, the solid carbon was characterised by Raman spectroscopy and by BET analysis. The solid carbon collected inside de plasma reactor was submitted to solid/liquid extraction and the desorbed species were identified by GC-MS.

Chemical composition of volatile oils from leaves of Nectandra megapotamica Spreng. (Lauraceae)

The volatile oils from Nectandra megapotamica Spreng. leaves, collected in February and August of 2007 and at 7:00 and 12:00 h (samples A - D), were extracted by hydrodistillation and the chemical composition was analyzed by GC-FID and GC/MS. A total of nineteen compounds were identified with predominance of oxygenated sesquiterpenes, among them, α-bisabolol, was the main constituent (62.3-69.4 %). After chromatographic separation procedures, this compound was purified from crude oil and its structure was confirmed by analysis of NMR data. This paper describes for the first time the composition of the leaves volatile oil from N. megapotamica.

Interespecific variation in the composition of volatile oils from the leaves of Swietenia macrophylla King (Meliaceae)

The volatile oils from leaves of five Brazilian specimens of Swietenia macrophylla King (Meliaceae) collected in three different Amazon Rainforest Conservation Areas in the States of Mato Grosso, Pará, and Rondônia were extracted and analyzed by GC and GC/MS. The oils showed to be composed by terpenoids, majority hydrocarbon sesquiterpenes, being germacrene D (20.5-46.8%) and bicyclogermacrene (8.3-11.1%) the main components. Besides these derivatives, only α-cubebene, β-caryophyllene, β-gurjunene and γ-cadinene were detected in all of the analyzed samples. This analysis indicated a great diversity of constituents in the oils obtained from specimens collected in these regions, which could be associated to the different susceptibility in the attack of H. grandella in S. macrophylla cultures.

Avaliação do uso de inibidores de etileno sobre a produção de compostos voláteis e de mangiferina em manga

Effects of two ethylene inhibitors, 1-methylcylopropene (1-MCP) and aminoethoxyvinylglycine (AVG), on production of volatile compounds and mangiferin (a bioactive xanthone) in 'Tommy Atkins' mango fruit were investigated. Volatile composition and mangiferin content, in treated and untreated fruits at three maturity, stages were determined by SPME-GC-MS and HPLC, respectively. These chromatographical analysis revealed that the volatile profiles and mangiferin concentrations were not significantly different, suggesting that the use of ethylene inhibitors does not affect the mango aroma and functional properties relative to this xanthone. Moreover, a simple, precise and accurate HPLC method was developed for quantifying mangiferin in mango pulp.

Aplicação de métodos quimiométricos na caracterização de charutos utilizando extração por dispersão da matriz em fase sólida e análise por cromatografia gasosa acoplada à espectrometria de massas

In this work, the organic compounds of cigar samples from different brands were analyzed. The compound extraction was made using the matrix solid-phase dispersion (MSPD) technique, followed by gas chromatography and identification by mass spectrometry (GC-MS) and standards, when available. Thirty eight organic compounds were found in seven different brands. Finally, with the objective of characterizing and discriminating the cigar samples, multivariate statistical analyses were applied to data, e.g.; principal component analysis (PCA) and hierarchical cluster analysis (HCA). With such analyses, it was possible to discriminate three main groups of three quality levels.

Ácidos naftênicos no petróleo

Brazilian petroleum is known by its high acidity due to the presence of acidic constituents, especially naphthenic acids (NA). The total characterization of the NA in petrochemical samples has been receiving special attention in research and comprises an analytical challenge, mainly due to the complexity of their mixtures. Gas chromatography with mass detector (GC/MS) is the technique of analysis more used, but recently comprehensive two-dimensional gas chromatography (GC × GC) has been used, due to its high resolution, peak capacity and sensitivity. The goal of this article is to discuss the techniques for sample preparation and analysis of NA in petroleum.

Extração de ácido trans-trans mucônico urinário com polímeros de impressão molecular e análise por cromatografia gasosa: espectrometria de massas

This paper describes selective molecularly imprinted solid-phase extraction of ttMA from urine samples followed by derivatization and analysis by gas chromatography/mass spectrometry (GC/MS). The analytical calibration curve ranged from 0.3 to 7.0 mg L-1 (r = 0.999) and the limit of quantitation (LOQ) was 0.3 mg L-1. The method was applied for the determination of ttMA in urine samples from smokers and concentrations detected ranged from < LOQ to 1.64 mg L-1. Thus, the proposed method proved adequate for the determination of urinary ttMA in the biomonitoring of occupational exposure to low levels of benzene.

Flavonoides e outros compostos isolados de Mimosa artemisiana Heringer e Paula

This the first phytochemical investigation of Mimosa artemisiana (Leguminosae-Mimosoideae) describing the isolation and identification of quercitrin, myricitrin, 3,5,4´-trihydroxi-6,7-dimethoxyflavone (6,7-dimethylkaepferol), flavolignans, 3-O-β-D-glucopyranosil sitosterol, lupeol, sitostenone, stigmastenone, campestenone, sitosterol, stigmasterol, campesterol, methyl indole-3-carboxilate and indole-3-carboxaldehyde in the extracts from the leaves and wood of this plant. This is the first registry of 6,7-dimethoxy,4'-hydroxy-flavona and the flavonolignans in this genera. The isolation of all metabolites was made by chromatographic methods and the structures were established on the basis of IR, MS, ¹H and 13C NMR spectra analysis, comparison with literature data and GC-MS of mixtures analysis.