Sewage contamination of Amazon streams crossing Manaus (Brazil) by sterol biomarkers.

Sewage pollution is a principal factor of decreasing water quality, although it has not been considered a real impact in Amazonia that is still considered a pristine environment around the world. Thus, this study aimed to assess the levels of sewage contamination in sediments from three streams crossing Manaus - a Brazilian city of 2,403,796 inhabitants in the heart of the Amazon rain forest. Cholesterol, cholestanol, brassicasterol, ergosterol, stigmasterol, ß-sitosterol, campesterol, stigmastanol, coprostanol, and epicoprostanol levels were determined by liquid chromatography tandem mass spectrometry (LC-MS/MS). The fecal indicator, coprostanol, was found in high concentrations (509-12 830 ng g-1) and high relative proportions (21-54%) in all samples collected in the Mindu stream that crosses many heavily populated districts of the city, and in the Quarenta stream that crosses the Industrial District of Manaus. The sediments of the Tarumã-Açu stream also presented coprostanol; however, concentrations (

PARAFAC HPLC-DAD metabolomic fingerprint investigation of reference and crossed coffees.

In this study two cultivars of Coffea arabica L., Bourbon (reference) and IPR101 (crossing) were analyzed. The extracts were prepared according to a simplex centroid design with four components, ethanol, ethyl acetate, dichloromethane, and hexane. Multiway data were obtained by HPLC-DAD analysis of the fifteen different mixtures for each cultivar. The PARAFAC methodology was used to investigate the chromatographic fingerprint. For both cultivars, Factor 1 was able to discriminate mixtures containing ethyl acetate as solvent. Factor 2 indicated that mixtures in pure ethanol and binary mixtures containing ethanol were the most efficient in extracting chlorogenic acids and factor 3 identified methylxanthines through spectrophotometric profile in all mixtures. Higher concentrations were obtained by the ethanol, dichloromethane and hexane ternary mixture for the Bourbon cultivar and by the quaternary mixture of these solvents with ethyl acetate for the IPR101 cultivar. Trigonelline and cafestol were extracted in both cultivars. The reference coffee showed higher relative abundances of cafestol ester, chlorogenic acids and trigonelline whereas the crossed coffee showed higher levels of caffeine. To confirm these results, UPLC-MS was used as a complementary method to confirm the presence of the metabolites in these extracts. The three way PARAFAC strategy determines correlations of HPLC-DAD chromatographic and spectral data simultaneously with samples permitting a more unambiguous assignment of metabolic groups than can be obtained treating chromatographic and spectral data separately by two way methods. This can provide higher quality chromatographic fingerprints for food chemistry.

Principal component and Tucker3 analyses of high performance liquid chromatography with diode-array detection fingerprints of crude extracts of Erythrina speciosa Andrews leaves.

Mixtures of ethanol, dichloromethane, hexane and acetone obtained according to a statistical design have been used to extract substances from Erythrina speciosa Andrew leaves for chromatographic fingerprinting. The plant extracts from each mixture were analyzed by HPLC-DAD providing UV-vis spectra for each chromatographic peak. These chromatograms and spectra for the design mixtures were then treated with principal component (PCA), Tucker3 and PARAFAC analyses. PCA indicated the existence of five different chromatographic fingerprints for the leave extracts depending on the solvent mixture composition. Different chromatographic peak areas were strongly correlated with the mixture proportions of acetone, dichloromethane and ethanol. Tucker3 and PARAFAC analyses were very useful for identifying simultaneous correlations between chromatographic peak areas, spectral band absorbances and solvent proportions. The acetone proportion was highly correlated with the area of the 3.69 min retention time peak and the spectral absorbances between 250 and 260 nm, consistent with the presence of natural polyphenols. The dichloromethane mixture proportion was strongly correlated with the 12.19 min chromatographic peak area and a single spectral absorbance at 201 nm. This spectral absorption is characteristic of the electronic structures of terpenes and alkaloids.

Statistical mixture design investigation of fractionated and total extracts from Erythrina speciosa Andrews leaves.

The simplex centroid mixture design for the ethanol, dichloromethane, hexane and acetone solvents has been applied to the extraction of crude mass and the fiber, organic, neutral and basic fractions as well as the fractionation residues of Erythrina speciosa Andrews leaves. Binary and ternary synergic solvent interactions are seen to provide dominant contributions to the extraction of both crude mass and all the fractions. Quadratic and special cubic mixture models precisely predict the extracted quantities of each fraction and the residue as a function of the proportions of the four solvents. Different solvent mixtures are found to be the most efficient extractors for the different fractions: binary dichloromethane-hexane mixtures for the fiber fraction, ternary ethanol-dichloromethane-acetone mixtures for the neutral fraction, binary ethanol-dichloromethane mixtures for the organic fraction, crude extract and residue values and ternary ethanol-dichloromethane-hexane mixtures for the basic fraction. Principal component analysis shows that the ethanol-dichloromethane mixtures are important for extracting large quantities of the basic and organic fractions as well as of the residue and crude masses.

Statistical mixture design--varimax factor optimization for selective compound extraction from plant material.

Varimax-transformed chromatograms of compounds extracted from Erythrina speciosa Andrews leaves by simplex centroid design mixtures of dichloromethane, hexane, ethanol and acetone are reported and compared with principal component results. Six varimax factors were investigated focusing on the three main groups of extracted compounds with retention times of 1.7, 3.1 and 6.6 min. Varimax models provide chromatographic loading profiles that are simpler than their principal component counterparts. Furthermore varimax score models in terms of extraction medium compositions are simpler to interpret. The first varimax model results in an optimum extraction mixture of 71% dichloromethane-29% acetone although substitution of acetone by ethanol results in an almost identical extraction profile. The second varimax score model predicts optimum extraction binary mixtures with hexane proportions ranging from 50 to 100% for complementary proportions of either acetone or ethanol. The third varimax factor provides a response surface that is very similar to the one found for the third PC. Confirmatory experiments were performed to validate the model predictions.

Multivariate chromatographic fingerprint preparation and authentication of plant material from the genus Bauhinia.

Multivariate analysis and statistical mixture designs were used for chromatographic fingerprint preparation and authentication of the plant material of three species of the genus Bauhinia. The extracts were analysed by reversed-phase high-performance liquid chromatography. Mixture design gave an optimum solvent composition for extracting components from the plants of 36% dichloromethane, 17% ethanol and 47% ethyl acetate (by volume), while an optimum mobile phase for chromatographic analyses was found to be 27% methanol, 27% acetonitrile and 46% of water (by volume). Results from principal component analysis, hierarchical analysis and soft independent modelling by class analogy showed that Bauhinia candicans cannot be synonymous with B. forficata Link. It was also possible to trace the metabolic profile without identifying its chemical constituents and to determine a chromatographic discriminating region. The characteristics responsible for discrimination between B. candicans and B. forficata were more polar substances that presented peaks with retention times around 1.65 and 1.81 min.

Statistical mixture design--principal component optimization for selective compound extraction from plant material.

A simplex centroid design is used to optimize solvent mixtures for selective extraction of compounds from Erythrina speciosa Andrews leaves. Three main groups of compounds characterized by chromatographic retention times of 1.7, 3.1, and 6.6 min were extracted. The chromatographic peak heights registered at 1407 equally spaced times for each design extract were converted into principal components (PCs). Three PCs account for 89.1% of the data variance and have important loading values at the above retention times. Quadratic mixture models were found to adequately describe the response surfaces of their PC score values. Maximizing the first PC scores while minimizing the second and third ones results in an optimum 83% dichloromethane-17% acetone mixture that selectively extracts the group of compounds with retention times around 3.1 min. Maximizing the second PC scores and minimizing the third PC scores leads to a 78% hexane-22% acetone mixture adequate for extracting the 6.6 min retention time compounds as well as other compounds with high retention times. The 1.7 min group of compounds is most efficiently extracted on maximizing the third PC that results in a 50% ethanol-50% acetone mixture. The Derringer-Suich algorithm confirmed the determination of these optimized mixtures.