Rosangela S. C. Lopes

Identification of source of a marine oil-spill using geochemical and chemometric techniques.

The current work aimed to identify the source of an oil spill off the coast of Maranhão, Brazil, in September 2005 and effect a preliminary geochemical survey of this environment. A combination of bulk analytical parameters, such as carbon isotope (δ(13)C) and Ni/V ratios, and conventional fingerprinting methods (High Resolution Gas Chromatography and Mass Spectrometry) were used. The use of bulk methods greatly speeded source identification for this relatively unaltered spill: identification of the likely source was possible at this stage. Subsequent fingerprinting of biomarker distributions supported source assignment, pointing to a non-Brazilian oil. Steranes proved the most useful biomarkers for sample correlation in this work. Distribution patterns of environmentally more resilient compound types, such as certain aromatic structures, proved inconclusive for correlation, probably in view of their presence in the background.

Straightforward synthesis of 2,2,4,4,5,7,7-d7-cholestane: a new deuterated standard in petroleum analysis

A short and efficient synthesis of heptadeuterated 2,2,4,4,5,7,7-d7-cholestane (1) from cholesterol (3) is described. The deuterated material will be useful for the analysis of different sources of petroleum in analytical geochemistry laboratories as internal standard for quantification of steranes via gas chromatography-mass spectrometry (GC-MS).

Preliminary study of insect attraction by a mixture of semiochemicals containing 1,2,4-Trimethoxybenzene in domestic citric-culture

In this work we describe a new efficient strategy for the preparation of 1,2,4-trimethoxybenzene (3) in 56% overall yield. The compound 3 was used in a preliminary study of insect attraction by a mixture of semiochemicals called TIV, composed of indol (1), vanillin (2) and 1,2,4-trimethoxybenzene (3), in eight Mc Phail style traps installed at a domestic orchard of citric-culture, containing 120 trees not infected by plagues in Bom Jesus Farm, located next to a patch of the Atlantic Forest, at Silva Jardim, Rio de Janeiro, Brazil.

Synthesis of 1,2,4-Trimethoxybenzene and Its Selective Functionalization at C-3 by Directed Metalation

Abstract A new and efficient strategy was developed for the preparation of 1,2,4-trimethoxybenzene (3, a powerful attractant of Euglossini bees) and its C-3 derivatives (7a–j), from vanillin (2) in 56% overall yield.

Total Synthesis of Altissimacoumarin D, a Small Molecule Sirtuin1 Activator

The total synthesis of the plant natural product altissimacoumarin D was achieved by the Mitsunobu alkylation of isofraxidin by geraniol. Isofraxidin was prepared from 2,4-dihydroxybenzaldehyde in five steps. The key reaction was the Knoevenagel condensation of an ortho-hydroxybenzaldehyde with Meldrum’s acid under neutral conditions in water and one-pot acid catalyzed cyclization to the coumarin.

Application of forensic luminol for blood detection in endodontic files

Introduction: Blood is a biological material with high potential of infectious transmission in dental environments, including herpes simplex, hepatitis and AIDS. Aim: To investigate the efficacy of luminol in detecting blood in endodontic files before and after the sterilization process. Material and method: Luminol was used to investigate the presence or absence of traces of blood tissue in 50 endodontic files, visible to naked eye or not, after performing endodontic treatment and after the cleaning/sterilization process. The results obtained were tabulated and statistically analyzed by using the Friedman’s test at a significance level of 5% (p<0.05). Result: By naked eye, it was found that 31/50 files showed no trace of blood, 8/50 showed a slight presence of blood and 11/50 showed a considerable presence of blood after endodontic treatment. After the use of luminol, however, 16/50 endodontic files showed no trace of blood, 19/50 showed a slight presence of blood and 15/50 showed a considerable presence of blood. After the cleaning and sterilization process, no blood was detected in the files. Conclusion: It was concluded that the luminol solution is effective in detecting blood tissue in endodontic files as well as in validating the cleaning/sterilization process. Descriptors: Endodontic file; endodontic therapy; endodontics; infection control.

Glicerofosfolipídios sintéticos para uso como aditivo biocida em tintas anti-incrustante

This paper presents a technological innovation that uses a subclass of glycerophospholipids as a booster biocide in antifouling paint. These glycerophospholipid PAF-analogs are economically and environmentally viable compounds because they are synthesized from a metal-free raw material source-soybean lecithin. The synthesis, which involves transesterification followed by an alkylation reaction, produced a mixture of glycerophospholipids that were characterized by mass spectrometry. Evaluation of the antifouling performance with field tests showed that the replacement of ordinary halogenated booster biocide with the synthesized product gave a better efficiency and an exceptional antifouling activity with a significant reduction in the coverage of the fouling macro-organisms.

Assessing Drug-Excipient Interactions in the Formulation of Isoniazid Tablets

A suitable and efficient high-performance liquid chromatography (HPLC) method was developed for the simultaneous determination of tuberculostatic isoniazid and its related impurities, isonicotinic acid and isonicotinamide, in oral solid dosage forms. We studied the influence on chromatographic separation of mobile phase parameters, such as pH, ion pairing and ionic strength, as well as column bonded phase and brands. The use of buffer solution pH 6.8:acetonitrile 96:4 (v/v) at 0.8 mL min-1, C18 column (250 × 4.6 mm, 5 µm), allowed proper separation of these ionizable analytes without the need of ion pairing agents. The limit of quantification of the method (0.1 µg mL-1) was suitable for the analysis of impurities. A drug-excipient compatibility study was carried out with the anaytical method proposed in this work and addressed frequent excipients used in isoniazid coated tablets. The dye FD&C blue 2 lake promoted the highest degradation of the tuberculostatic agent.

Metodologias de síntese de 2-arilcicloexanonas

Several methodologies concerning the preparation of 2-aryl and 2-heteroarylcyclohexanones are presented. The use of these intermediates in the synthesis of chemically and biologically interesting organic compounds is also discussed.