M. A. Barbirato
University of São Paulo
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Featured researches published by M. A. Barbirato.
Chromatographia | 1994
Fernando M. Lanças; M. S. Galhiane; M. A. Barbirato
SummaryThis work describes the study of a degradation curve of Oxadixyl in field-treated potato and tomato samples. The residues were extracted using classical and supercritical fluid (SFE) extraction methods and analyzed by HRGC/ECD. The extraction techniques were compared and the results indicate the advantages of using SFE as an alternative method for pesticide analyses in these samples.
Chromatographia | 1995
Fernando M. Lanças; M. A. Barbirato; M. S. Galhiane
SummaryA new method for the extraction of Norflurazon residues in cotton seeds using supercritical CO2 as the extracting fluid is described. The supercritical fluid extraction results were compared with those of the classical procedure using liquid extraction. All SFE experiments were performed using a home-made system. The method presented, besides being faster and more economical than existing methods, showed better recovery, with higher selectivity for Norflurazon extraction.
Chromatographia | 2000
José D. Fontana; Maurício Passos; M. H. R. dos Santos; C. K. Fontana; Bruno Oliveira; L. Schause; Roberto Pontarolo; M. A. Barbirato; M. A. Ruggiero; Fernando M. Lanças
SummaryThere is no proportional correlation between increasing organic solvent polarity from hexane to methanol and the extractability of propolis solids by the solvents or the bactericidal action of the propolis extracts obtained. Hexane (17.7%) and chloroform (62.1%) were the poorest and the best extractants, respectively, for propolis solids. The antibiotic activity of the extracts againstStaphylococcus strains decreased in the order hexane≥ethanol>methanol. Different capillary GC profiles were obtained for persilyl derivatives of propolis extracted with hexane and methanol and for propolis collected in different Brazilian provinces, suggesting the influence of flora variability on propolis composition. Wavelength-selected DAD detection revealed MEKC to be an innovative and sensitive method for monitoring the occurrence in propolis of the flavonoids and phenolcarboxylic acids thought to be responsible for the antimicrobial activity of propolis.
Chromatographia | 1996
Fernando M. Lanças; M. A. Barbirato; M. S. Galhiane; Sandra R. Rissato
SummaryA new method for the extraction of Chlorothalonil residues from apples using supercritical CO2 as the extracting fluid is described. The supercritical fluid extraction results were compared with those obtained by solid-liquid extraction. The results showed that SFE is faster and more selective with better recovery and higher selectivity.
Chromatographia | 1996
Fernando M. Lanças; M. A. Barbirato; M. S. Galhiane
SummaryNorflurazon and Oxadixyl residues have been analysed by HRGC-ECD after extraction from field-treated sugar cane and grapes using classical solid-liquid extraction or supercritical fluid extraction. The extraction techniques were compared; the results indicate the advantages of SFE as an alternative method for analysis of pesticides in these samples.
Chromatographia | 1996
Fernando M. Lanças; M. A. Barbirato; M. S. Galhiane
SummaryIn this work we present a new procedure for extraction of Atabron residues from cabbage samples using supercritical carbon dioxide. The results obtained with this procedure were compared with those obtained using traditional extraction methods for Atabron residues. The extraction yields found by both procedures are similar but SFE has several advantages, especially higher speed, greater economy, better selectivity and greater reproducibility.
Petroleum Science and Technology | 1994
Fernando M. Lanças; M. A. Barbirato
Abstract The present work describes a novel method for the isolation of the neutral N-containing fraction from crude oil using column liquid chromatography on silica gel chemically modified with Ti(IV) oxide using a grafting method. The crude oil sample is introduced onto the column and eluted with a proper sequence of eluents. The first eluted fraction contains only hydrocarbons. The N-containing compounds are eluted in a isolated fraction. Both fractions are collected, concentrated and analyzed using HRGC with NPD detection. The method is shown to be very selective for the isolation of the neutral N-containing fractions from crude oil.
Petroleum Science and Technology | 1994
Fernando M. Lanças; M. A. Barbirato
Abstract In the present work we describe a novel method for the isolation of the neutral N-containing fraction from crude oil by preparative liquid chromatography using thermally treated silica gel as stationary phase. The hydrocarbons are eluted in the first two fractions and the nitrogen compounds in the third fraction. The collected fractions are analyzed by HRGC-NPD. The method is shown to be very selective for the isolation of nitrogen compounds from the neutral fractions of crude oil.
Food Science and Technology International | 1997
Fernando M. Lanças; M. A. Barbirato; M. S. Galhiane; Sandra R. Rissato
In the present work, we describe a SFE home-made system used for pesticide residue extraction in food products. The pesticides were extracted using CO2 in the supercritical state as extracting fluid with and without modifiers. The results obtained by SFE have been better than those obtained by conventional extraction method.
Hrc-journal of High Resolution Chromatography | 1997
Fernando M. Lanças; Mario Sergio Galhiane; Sandra Regina Rissato; M. A. Barbirato