Ion pair-dispersive liquid-liquid microextraction of trace amount of rhodium ion in water and road dust samples prior to flame atomic absorption spectrometry determination

A simple ion pair-dispersive liquid-liquid microextraction method was proposed for preconcentration trace amounts of rhodium. An ion association complex of RhCl4- and tetradecyldimetylbenzylamonium was extracted into cholorobenzene. The volume and the type of extractive and dispersive solvents, the extraction time and the pH of the aqueous solutions were optimized. The calibration curve was linear in the range of 0.6-500 ng mL-1 of rhodium. The limit of detection was 0.10 ng mL-1 in initial solution and preconcentration factor was 40. The proposed method was successfully applied to the extraction and determination of rhodium in road dust and water samples.

Recuperação de compostos de iodo de reagentes e soluções laboratoriais

This work presents simple routes to recover iodine compounds from oxidized laboratory chemicals and aqueous solutions (HI and KI) used in laboratory chemistry classes. These routes are based on the oxidation of iodide ions (I-) to iodine (I2) by an oxidant (H2O2) or reduction of oxidized iodine by red phosphorus or hydrazine. Both routes presented high yields. The oxidative route is of general use whereas the reductive one is appropriate for restoring original iodine reagents. Final wastes were generated in low amounts. This work is appropriate for teaching many laboratory techniques (e.g., distillation, titration and filtration) in the chemical laboratory.

Furfural - da biomassa ao laboratório de química orgânica

The goal of this manuscript is provide to students of Chemistry and related areas an alternative experiment in which they can obtain a compound and learn to observe and interpret properties and predict organic structure by obtaining furfural from biomass. Furfural is an organic compound, obtained through acid hydrolysis of pentosans, commonly used in the chemical and pharmaceutical industries. Students are guided to get furfural through extractive procedures and chemical reactions adapted to semi-micro laboratory scale. Characterization of furfural was done by chemical tests and physical properties. Identification was accomplished by a series of spectroscopic and spectrometric techniques.

Comparação do perfil químico entre cachaças de um mesmo vinho destiladas em alambiques e em colunas

Six wines were distilled in two different distillation apparatus (alembic and column) producing 24 distillates (6 for each alembic fraction - head, heart and tail; 6 column distillates). The chemical composition of distillates from the same wine was determined using chromatographic techniques. Analytical data were subjected to Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) allowing discrimination of four clusters according to chemical profiles. Both distillation processes influenced the sugarcane spirits chemical quality since two types of distillates with different quantitative chemical profiles were produced after the elimination of fermentation step influence.

Miniprojeto para ensino de química geral experimental baseado na fermentação do caldo de cana-de-açúcar

This paper describes a five-week mini-project for a general chemistry laboratory course. Activities are included preparations of ethanol and sucrose solutions, calculation of concentrations, determination of densities with densimeters, sugarcane juice fermentation with CO2 capture in alkaline solution, distillation, and determination of amounts of ethanol and CO2 formed. Abilities and concepts normally present in practical general chemistry courses are covered: use of balances, volumetric glassware and densimeters, preparation of solutions, performing of dilutions, determination of solution densities, observation of chemical reactions, stoichiometric calculations, separation of mixtures, and titration.

A fração volátil das aguardentes de cana produzidas no Brasil

The volatile fraction of sugar cane spirits plays a key role in the quality and acceptance of these beverages. The composition of this fraction is dependent on the way sugar cane collection, fermentation, distillation and aging are carried out. The materials used in these processes strongly influence chemical composition. Acetic acid, acetaldehyde, ethyl acetate, ethanol, 2.3-butanedione, n-propanol, 3-methyl-buthanol and isobuthanol were the major volatiles in spirits. Dimethyl sulfide and n-propanol impaired beverage flavor. Ethyl octanoate, 1.1-diethoxy-ethane, 2-phenylethanol and 3-methyl-butanol were important aroma contributors. Ageing allows the extraction of flavor-active components (e.g., phenolic compounds) from wood.

Variation of essential oil composition of Tapirira guianensis Aubl. (Anacardiaceae) from two sandbank forests, north of Brazil

Tapirira guianensis (Anacardiaceae) is used in traditional medicine and is important for the recovery of degraded areas and riparian forests because the T. guianensis fruits are highly consumed by wildlife. Volatile components from dried leaves and branches of five individual plants of T. guianensis were collected in two sandbank forests of the State of Pará (Extractive Reserve Maracanã and Area of Environmental Protection Algodoal/Maiandeua), extracted by hydrodistillation using a Clevenger-type apparatus, and analyzed by GC/MS. The ten oils obtained are comprised mostly of sesquiterpene hydrocarbons (58.49 to 100%), with (E)-caryophyllene, β-selinene, α-selinene, β-sesquiphellandrene, and α-zingiberene being the most prominent. The results of the oil compositions were processed by Hierarchical Component Analysis (HCA) allowing the establishment of three groups of essential oils for T. guianensis differentiated by the content of β-selinene/α-selinene (Type I), (E)-caryophyllene (Type II), and β-sesquiphellandrene/α-zingiberene (Type III).

Optimization of NMP extraction in 1, 3-butadiene production line

N-methylpyrrolidone is a powerful solvent for variety of chemical processes due to its vast chemical properties. It has been used in manufacturing processes of polymers, detergents, pharmaceuticals rubber and many more chemical substances. However, it creates large amount of residue in some of these processes which has to be dealt with. Many well known methods such as BASF in rubber producing units have tried to regenerate the solvent at the end of each run, however, there is still discarding of large amount of residue containing NMP, which over time, could cause environmental concerns. In this study, we have tried to optimize regeneration of the NMP extraction from butadiene production. It is shown that at higher temperatures NMP is separated from the residue with close to 90% efficiency, and the solvent residue proved to be the most effective with a 6: 1 ratio.

Extractives and energetic properties of wood and charcoal

Charcoal production stands out as a raw material for the production of renewable energy. To assess wood quality in energy terms, studies have focused more on the holocellulose and lignin content than on the role of extractives. The objective of this study was to evaluate the relationship between the extractive content in cold water, in dichloromethane and total on energy properties of wood and charcoal, from six trees species. The extractives were removed with different solvents to be recorded and gross calorific value of wood was determined. The wood was carbonized at 1.67°C/min heating rate until maximum of 450°C and residence time of 30 min. The extractive content was correlated with the gravimetric yield, apparent relative density, ash, volatile matter, fixed carbon and gross calorific value of charcoal. The removal of total extractives and extractives soluble in dichloromethane reduced the gross calorific value of wood of most species evaluated. The extractives removed in cold water did not correlate with the parameters of carbonization. The extractives content in dichloromethane correlated with volatile matter, fixed carbon and gross calorific value. Total extractive content correlated with gravimetric yield, apparent relative density and gross calorific value of charcoal.

EFFECTS OF HARVESTING ON LEAF PRODUCTION AND REPRODUCTIVE PERFORMANCE OF Copernicia prunifera (Mill.) H.E. Moore1

ABSTRACT This work aimed to evaluate the consequences of the monthly extraction of immature leaves in survival, leaf production and reproductive performance ofCopernicia prunifera H. E. Moore palm, popularly known as carnaúba. One hundred sixty reproductive adult palms were monitored for 17 months in four extractive communities located at the coast of the state of Piauí. As a result, it was observed that leaves, flowers, fruits and seeds production were reduced in the palm submitted to 50% or 75% monthly extraction. Higher levels of extraction were followed by smaller levels in seed germination. No deaths were observed even in the group subjected to 75% monthly leaves exploration. In order not to produce damage to palm trees development it is suggested that leaf extraction rate should not exceed 25% monthly as well as pausing of extractive activity preferentially during fruit maturation.

Antimicrobial activity and acute and chronic toxicity of the essential oil of Lippia origanoides

Currently, there is a growing interest in medicinal plants, because of an increased demand for alternate therapies. In this study, the antimicrobial activity and toxicity of the essential oil of Lippia origanoides (L. origanoides) were investigated. The essential oil of L. origanoides was extracted by steam-dragging distillation and its constituents were identified by chromatography coupled with mass spectrometry. Among the 15 compounds identified, the most abundant were carvacrol (29.00%), o-cymene (25.57%), and thymol methyl ether (11.50%). The essential oil was studied in antimicrobial assays to determine the MIC and MBC. The results indicated that a concentration of 120μL/mL of oil was sufficient to inhibit the growth of the following microorganisms: Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923) and Salmonella cholerasuis (ATCC 10708). Acute and chronic toxic effects of orally administered oil were investigated in Wistar rats by using standard methods. Doses of 30, 60 and 120mg/kg of the essential oil did not induce significant changes in weight, behavior or hematological and biochemical parameters in the animals. There were no signs of any histopathological changes to the liver, kidneys or heart of the treated rats, suggesting that Lippia origanoides oil is non-toxic after oral administration in acute or chronic toxicity studies. The results obtained in this study show that the essential oil of L. origanoides has a high safety margin, with no detectable toxic effects in rats treated with doses to 120mg/kg. In addition, L. origanoides oil demonstrated potent antimicrobial activity against S. aureus, E. coli and S. cholerasuis. Based on these findings, this essential oil may have practical application as a veterinary antimicrobial.

Antimicrobial activity of the essential oil from Lippia sidoides, carvacrol and thymol against oral pathogens

Dental caries and periodontal disease are associated with oral pathogens. Several plant derivatives have been evaluated with respect to their antimicrobial effects against such pathogenic microorganisms. Lippia sidoides Cham (Verbenaceae), popularly known as "Alecrim-pimenta" is a typical shrub commonly found in the Northeast of Brazil. Many plant species belonging to the genus Lippia yield very fragrant essential oils of potential economic value which are used by the industry for the commercial production of perfumes, creams, lotions, and deodorants. Since the leaves of L. sidoides are also extensively used in popular medicine for the treatment of skin wounds and cuts, the objective of the present study was to evaluate the composition and antimicrobial activity of L. sidoides essential oil. The essential oil was obtained by hydro-distillation and analyzed by GC-MS. Twelve compounds were characterized, having as major constituents thymol (56.7%) and carvacrol (16.7%). The antimicrobial activity of the oil and the major components was tested against cariogenic bacterial species of the genus Streptococcus as well as Candida albicans using the broth dilution and disk diffusion assays. The essential oil and its major components thymol and carvacrol exhibited potent antimicrobial activity against the organisms tested with minimum inhibitory concentrations ranging from 0.625 to 10.0 mg/mL. The most sensitive microorganisms were C. albicans and Streptococcus mutans. The essential oil of L. sidoides and its major components exert promising antimicrobial effects against oral pathogens and suggest its likely usefulness to combat oral microbial growth.

Comparison of volatile and polyphenolic compounds in Brazilian green propolis and its botanical origin Baccharis dracunculifolia

Ethanolic extracts and essential oils from Green Propolis from southeastern Brazil and leaf buds from its botanical origin Baccharis dracunculifolia were analyzed by Reversed Phase High Performance Liquid Chromatography (RP-HPLC), Reversed Phase High Performance Thin Layer Chromatography (RP-HPTLC) and Gas Chromatography - Mass Spectrometry (GC-MS). The essential oils were obtained by hydro-distillation. Both ethanolic extracts and essential oils showed similar chromatographic profiles. Thirteen flavonoids were identified by RP-HPLC and RP-HPTLC analyses in both samples. Twenty-three volatile compounds were identified by GC-MS analyses. Seventeen were present in both essential oils. The major flavonoid compound in both extracts was artepillin C. The major volatile compound in both essential oils was nerolidol. The major compounds identified in this work could be used as chemical markers in order to classify and identify botanical origins of propolis.

Microbiological and physicochemical evaluations of juice extracted from different parts of sugar cane stalks from three varieties cultivated under organic management

The artisanal production of cachaça, a beverage obtained by the fermentation of sugar cane juice after distillation, especially by small-sized producers, has traditionally used natural ferment ("fermento caipira") which consists of sugar cane juice with crushed corn, powdered rice, or citrus fruits. In despite of the difficulties in quality control due to the high level of contaminants and longer periods of preparation, the sensorial quality of the beverage may be attributed to the physiological activities of wild yeasts and even bacteria present during fermentation when this ferment is used. In this context, the aim here was to evaluate the microbiological (yeasts) and physicochemical characteristics of sugar cane juice extracted from different parts of three different varieties (RB72454, RB835486, and RB867515) of the cane stalk (lower, medium, and upper sections) in three harvesting periods (from May to December 2007) in an area under organic management. The juice from the upper section (from the eleventh internode to the top) of the sugar cane stalk could be indicated for the preparation of the natural ferment since it is as a source of yeasts and reducing sugars, especially the variety RB867515. Due to the seasonality, the best period for using this part of the sugar cane stalk is at the beginning of harvesting when the phenolic compounds are at low concentration, but there are higher number of Saccharomyces population and other yeast species. The high acidity in this section of the plant could result in a better control of bacterial contamination. These findings explain the traditional instructions of adding the upper sections for the preparation of natural ferment and can help its management in order to get a better performance with respect to organic cachaça production.

Antioxidant activity, cito- and phototoxicity of pomegranate (Punica granatum L.) seed pulp extract

In the present work, a hydroethanolic extract was prepared from the entire seeds of pomegranate [Punica granatum L. (Punicaceae)] with Cachaça, a distilled Brazilian alcoholic beverage, protected from light for an 80-hour period. The desorption curve of the seeds, presented an optimal time extraction of approximately 24 hours. The extract was divided into two samples: protected from light, (Extract 1), or not, (Extract 2). The extracts were characterized by UV-Visible absorption spectroscopy, quantification of total phenolics by the Folin-Ciocalteu method, and the antioxidant activity was determined by the DPPH quenching method. Extract 2 presented 9.8% less total polyphenols than Extract 1. The pomegranate seeds extract lost 79% of its antioxidant activity during light exposure. Extract 1 up to 3% (w/v) showed neither cyto nor phototoxicity in the Hela cells. In conclusion, Punica granatum L. seeds contain a significant total polyphenol and TEAC amount and they can be used in simple extractive process, by direct contact with Cachaça in up to 80 hours in the darkness, which gives it good coloration, taste, and smell. This extract showed neither cytotoxicity nor post-irradiation phototoxicity with solar simulator even though the extract proved photoinstable.