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The aims of this study were to formulate calcium-alginate beads containing glibenclamide, characterize the resulting microparticles, evaluate the release characteristics of this type of delivery system in an in vitro dissolution test, and compare it with two commercially available trademarks (Daonil® and Glibetab®). We obtained glibenclamide loaded calcium-alginate beads with a rough surface and a particle size between 150-200 µm. For the in vitro dissolution test Daonil® at 45 min showed a Q > 70%, whereas Glibetab® and glibenclamide calcium-alginate beads a Q < 70%; in spite of that glibenclamide calcium-alginate beads showed significant release properties.

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Saponins are natural soaplike foam-forming compounds widely used in foods, cosmetic and pharmaceutical preparations. In this work foamability and foam lifetime of foams obtained from Ilex paraguariensis unripe fruits were analyzed. Polysorbate 80 and sodium dodecyl sulfate were used as reference surfactants. Aiming a better data understanding a linearized 4-parameters Weibull function was proposed. The mate hydroethanolic extract (ME) and a mate saponin enriched fraction (MSF) afforded foamability and foam lifetime comparable to the synthetic surfactants. The linearization of the Weibull equation allowed the statistical comparison of foam decay curves, improving former mathematical approaches.

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This work presents a density functional theory study of the norbornene ROMP metathesis reactions. The energies have been calculated in a Grubbs catalyst model Cl2(PH3)2Ru=CH2. The geometries and energy profile are similar to the Grubbs metilydene (Cl2(PCy3)2Ru=CH2 real model. It was found that the metathesis reaction proceeds via associative mechanism (catalyst-norbonene) followed by dissociative substitution of a phosphine ligand with norbonene, giving a monophosphine complex. The results are in reasonable agreement with the available experimental data. The dissociation energy of the phosphines is predicted to be 23.2 kcal mol-1.

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This study aimed to evaluate the chemical elements levels in soil, submitted to different management systems and use by the Energy Dispersive X-Ray Fluorescence Spectrometry - EDXRF. The systems were T1 - agro forestry (SAF), T2 - Native Field (CN), T3 - Native Forest (NM), T4 - Tillage Forest (PF); T5 - conventional tillage system (SPC) and T6 - System tillage (NT). Samples were collected at 0-10 and 10-20 cm, dried and ground for analysis in EDX-720. The soil showed no difference in the average concentrations of chemical elements analyzed in the profiles, but the systems presented different concentrations of metal elements, and T3 had the highest K, Ca and Zn at 0-10 cm and higher contents of K, Ca, Cu, Zn and Mn in the layer of 10-20 cm.

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The reaction of 4-(phenyl)thiosemicarbazide with isatin yielded a new ligand, isatin-3-(N4-benzylthiosemicarbazone). Isatin-3-(N4-benzylthiosemicarbazone) deprotonated in ethanol/KOH reacts with an ethanolic solution of Hg(NO3)2 to give a mercury complex. The compounds were characterized by IR and X-ray single crystal structure determination. The X-ray studies revealed that the complex possesses a tetrahedral geometry with two deprotonated thiosemicarbazone ligands coordenated. The ligand and its mercury complex crystallize in the monoclinic (P2(1)/c) and triclinic (P-1) crystal system, respectively.

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The influence of temperature (30 and 40 ºC) and soil humidity (20, 50 and 70% of water holding capacity) on the degradation of the herbicide diurom and the endosulfan metabolite, endosulfan sulfate was studied under laboratory conditions, in different soil layers (0-30, 30-38 and 38-83 cm) of an Oxisol (Yellow Latosol) collected in an agricultural area of Mato Grosso State, Brazil. Endosulfan sulfate was rapidly degraded under lower soil humidity, higher temperature and deeper soil layers. For diurom the opposite was observed as a consequence of its higher water solubility and lower soil sorption coefficient.

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Tucker-3 model offers several advantages for analysis of environmental data but its interpretation is still challenging. A Tucker-3 model was applied to a biodegradation experiment involving a large number of overlapped chromatographic peaks and a temporal variation. The Tucker-3 model allowed the data to be decomposed in two processes: evaporation and biodegradation. The results suggest that linear hydrocarbons were those biodegraded first and demonstrate that the data analysis can be simplified by interpreting the elements of the core array. The approach discussed in this work can be applied in similar problems involving multi-way data in other areas of chemistry.

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Cefdinir has broad spectrum of activity and high prescription rates, hence its counterfeiting seems imminent. We have proposed a simple, fast, selective and non-extractive spectrophotometric method for the content assay of cefdinir in formulations. The method is based on complexation of cefdinir and Fe under reducing condition in a buffered medium (pH 11) to form a magenta colored donor-acceptor complex (λ max = 550 nm; apparent molar absorptivity = 3720 L mol-1 cm-1). No other cephalosporins, penicillins and common excipients interfere under the test conditions. The Beer's law is followed in the concentration range 8-160 µg mL-1.

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The quaternary chitosan was synthesized by reaction of chitosan with glycidyl trimethylammonium chloride. it was characterized by infrared spectra and conductometric titration. Adsorption of reactive blue 4 (RB4) and reactive red 120 (RR120) by quaternary chitosan was studied from aqueous medium. Two kinetic adsorption models were tested: pseudo first-order and pseudo second-order. The experimental data best fitted the pseudo second-order model. The Langmuir isotherm model provided the best fit to the equilibrium data in the concentration range investigated and the maximum adsorption capacity determined was 415 mg (RR120) and 637 mg (RB4) of reactive dye per gram of adsorbent.

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This paper describes 2D-QSAR and 3D-QSAR studies against Candida albicans and Cryptococcus neofarmans for a set of 20 bisbenzamidines. In the studies of 2D-QSAR with C. albicans it was obtained a correlation between log MIC-1 and lipolo component-Z (r² = 0.68; Q² = 0.51). In the case of C. neofarmans a correlation between log MIC-1 and lipolo component-Z and of Balaban index (r² = 0.85; Q² = 0.6) was obtained. 3D-QSAR studies using CoMFA showed that the steric fields contributed more to the predicted activities for Candida albicans (94.9%) and Cryptococcus neofarmans (97.9%).

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The variability in aflatoxin B1 concentration among peanut subsamples of 4 sample preparation procedures was evaluated. For each procedure, 18 samples were prepared involving dry comminuting/homogenization or dry roughly comminuting followed by the preparation of a aqueous slurry. Ten analytical samples were withdrawn from each sample/procedure and analyzed by thin layer chromatography. The coefficient of variation (CV%) among each set of 10 analytical samples was assumed to be associated with the sample preparation procedure. The procedure that made use of a subsample mill and preparation of a subsample slurry, showed lower variability (CV%) among the analytical subsamples.

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The application of organo nanoclay 5-(4-dimethylamino-benzylidene) rhodanine-immobilized as a new, easily prepared, and stable solid sorbent for preconcentration trace amounts of Au(III) ions in aqueous solution is presented. The sorption of Au(III) ions was quantitative in the pH range of 2-4, and quantitative desorption occurred instantaneously with 10.0 mL of a mixture containing 0.5 mol L-1 Na2S2O3 and KSCN. Various parameters, such as the effect of pH, breakthrough volume, extraction time, and interference of a large number of anions and cations have been studied. The proposed method has been applied for determination of trace amount of gold in water samples.

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The study of pyrolysis is gaining increasing importance, since it is the first step in the gasification or combustion process. In this study, pyrolysis experiments of cypress pine were carried out in a thermogravimetric analyzer at six different heating rates between 5 and 40 ºC / min. Kinetics parameters of pine were determined from TGA by using the differential and the maximum speed methods. Additionally, the distribution of activation energies was also carried out finding the values of 113.57 and 157.32 kJ/mol, which are in the range of activation energies reported for hemicellulose and cellulose, respectively, main components of wood.

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This work describes the volatile composition obtained by hidrodistillation of fresh leaves of Siparuna guianensis Aublet collected from Cuiabá (MT), Brazil. The composition of DCM extract of hydrolate was determined by GC-MS analysis and the results showed that the specie present a range of components according to their phenology and period of the leaves were collects. The highest volatile components yield was obtained during the reproductive period and the principal compound was the siparunone.

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The volatile oil from the leaves of E. urograndis was analyzed by GC and GC-MS. It was identified 10 compounds in which, orto-cimene (41.4%) and 1,8-cineol (25.8%) were the main constituents. The induction of deleterious effect to aquatic organisms due to the presence of volatile oil lixiviated from E. urograndis leaves was studied using Daphnia laevis and D. similis as bioindicators. Through the results of toxicological tests it was possible to show that the litterbag of E. urograndis represents a risk factor for the aquatic ecosystem of lakes and rivers that are in the surrounding area of large scale Eucalyptus plantations. The method can be used for monitor the quality of these types of aquatic environments.

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We investigated the impact of sulphate and the redox mediator Anthraquinone-2,6-disulfonate (AQDS) on the decolorization of the azo dyes Congo Red (CR) and Reactive Black 5 (RB5). In anaerobic reactors free of extra sulphate dosage, the color removal efficiency decreased drastically when the external electron donor ethanol was removed. In presence of an extra dosage of sulphate, CR decolourisations were 47.8% (free of AQDS) and 96.5% (supplemented with AQDS). The decolourisations achieved in both reactors with RB5 were lower than the ones found with CR. Finally, the biogenic sulphide contribution on azo dye reduction was negligiable.

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Cyanogenesis in Pteridium caudatum and P. arachnoideum has been examined. Samples of the Andes of South America furnished from 0 to 4.63 mg of prunasin g-1 of frond dry weight (dw) in P. caudatum and from 0 to 103 mg of g-1 dw in P. arachnoideum. In both fern species the continuous distribution of prunasin suggested cyanogenic polymorphism. The frequency of cyanogenic morphs was 84.7% for P. caudatum and 98.6% for P. arachnoideum. Cyanogenic activity was highest in the young crozier and waned rapidly with frond growth. The crozier head was found to yield HCN much more than the stipe.

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This work proposes the study of heterogeneous photocatalysis using TiO2 impregnated in zeolites beta, ZSM-5, mordenite, NaXb, NaXp and NaY for the decomposition of methylene blue. The catalysts were characterized by XRD, IR, textural analyses by N2 adsorption, SEM, DRS and the reaction of decomposition was monitored by UV visible. The results indicated that didn't have structural changes in the catalysts after Ti impregnations, only in the case of NaY and NaX zeolites. The better photocatalyst to metylene blue decomposition was beta/Ti zeolite due had one structure more accessible (with bigger porous) helping in TiO2 dispersion and catalytic active.

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A method for selective determination of tributyltin in the presence of Sn(IV) by combining hydride generation inductively coupled plasma optical emission spectrometry (HG-ICP OES) and solid phase extraction (SPE) using baker's yeast is proposed. The procedure is based on selective retention of TBT by the yeast at pH = 6. Detection limit of 1.9 µg L-1 and quantification limit of 6.3 µg L-1 were obtained. TBT and San(IV) were determined in the range of 0-25 µg L-1 and the proposed approach was applied to analyze river water, sea water and biological extracts, with recoveries of 114, 101 and 86%, respectively.

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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.

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Leishmania causes tegumental and visceral diseases called leishmaniasis. Disease control is possible interrupting the transmission cycle, but HIV co-infection, chemotheraphy toxicity and lack of a vaccine are paramount difficulties. So, is necessary to study new Leishmania molecules and investigate the possibility to develop rational drugs using these molecules as targets. Leishmania express many peptidases during their life, and cysteine are the most abundant protease and many inhibitors were developed but failed to kill parasites. On the other hand, inhibitors of serine proteases killed promastigotes, indicating the possibility of these enzymes to be important targets in the development of anti-Leishmania drugs.

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Production of ethanol from biomass fermentation has gained much attention recently. Biomass cellulosic material is first converted into glucose either by chemical or by enzymatic process, and then glucose is fermented to ethanol. Considering the current scenario, where many efforts are devoted for the search of green routes to obtaining ethanol from renewable sources, this review presents the relationship between structure and properties of cellulosic material, pre-treatments and hydrolysis of cellulosic material, and structure and function of cellulase enzyme complex.

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This review first discusses the limitations of many of the supports and stationary phases used in reversed phase high performance liquid chromatography and then describes those, developed more recently, that present better stabilities and more versatile selectivities. Emphases will be given to stationary phases that use higher purity silicas, hybrid silicas, monolithic silicas, metallic oxides and mixed oxides as supports and those that have embedded polar groups or contain phenyl or fluoro groups as the stationary phase as well as the phases used for mixed mode or hydrophilic interaction separations. These modern stationary phases facilitate the analysis of complex mixtures.

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Pulp hemicelluloses can be extracted with NaOH and quantified by colorimetric and gravimetric techniques. However the most usual methods to measure eucalyptus pulp hemicelluloses have been through the pentosan method or through xylan analyses by GC or HPLC techniques. In this study a comparison was made between the more traditional methods and indirect method of NaOH 5% extraction followed by colorimetric analyses. It was observed that the content of NaOH 5% extract correlates very well with pulp xylan content and reasonably well with the pentosan content. It is concluded that the 5% NaOH solubility method can be used in replacement of the other two, since it is faster, simpler and less costly to carry out than the others.

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A bacterium isolated from soil contaminated by hydrocarbon was studied and, by biochemical tests and analysis of PCR, the presence of Bacillus pumilus was identified. The production of biosurfactant was optimized, test of oil degradation and antimicrobial activity determination. The results showed that pH 5.0 and 7.0, 72 h of fermentation, sucrose and sugar cane juice (2%) had best yields. The bacterium is able to degrade crude oil and displays bacteriostatic and fungistatic activity. From the analysis of proximate composition of biosurfactant found the presence of biopolymer formed by a lipopolysaccharide-protein complex.

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The measurement uncertainty is useful to estimate the confidence of analytical results. Nowadays, a result without the uncertainty statement cannot be considered reliable, but the scientific literature still lacks examples of the estimate of the measurement uncertainty. This paper presents a practical and reliable description of the measurement uncertainty estimation of the analytical determination of ethyl carbamate in cachaça by GC-IDMS. The isotope dilution technique (ID) associated with GC-MS was used to improve the accuracy. The uncertainty estimated corresponds to 10% of the mass fraction of ethyl carbamate (115 ± 11) ng/g, which is in agreement with ppb level.

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This work describes the validation of a method for quantification of famotidine in capsules by UV spectrophotometry using as solvents buffer solution at pH 2.5 and buffer solution at pH 4.5. The results show that the method is practical, selective, accurate, precise and linear from 10.0 to 25.0 µg/mL of famotidine in both solvents. However, a variance analysis showed a lower mean percentage of famotidine when buffer at pH 2.5 is used. This effect was attributed to the instability of famotidine in acidic media. Therefore, the use of pH 4.5 buffer was considered suitable for analysis of famotidine in capsules.

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An isocratic reversed phase high-performance liquid chromatographic (RP-HPLC) method has been developed for the simultaneous determination of gemifloxacin and diuretics (hydrochlorothiazide and furosemide) in bulk, dosage formulations and human serum at 232 nm. Chromatographic separation was achieved on Purospher Start C18 (250 mm x 4.6 mm, 5 µm) column using mobile phase, methanol: water: acetonitrile (70:25:5 v/v/v) adjusted to pH 3.0 via phosphoric acid 85% having flow rate of 0.8 mL min -1 at room temperature. Calibration curves were linear over range of 0.5-10 µg mL -1 with a correlation coefficient ± 0.999. LOD and LOQ were in the ranges of 0.75-2.56 µg mL -1. Intra and inter-run precision and accuracy results were 98.26 to 100.9.

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A dataset of chemical properties of the elements is used herein to introduce principal components analysis (PCA). The focus in this article is to verify the classification of the elements within the periodic table. The reclassification of the semimetals as metals or nonmetals emerges naturally from PCA and agrees with the current SBQ/IUPAC periodic table. Dataset construction, basic preprocessing, loading and score plots, and interpretation have been emphasized. This activity can be carried out even when students with distinct levels of formation are together in the same learning environment.

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An undergraduate physical chemistry experiment based on the drop counting method for surface tension measurements is proposed to demonstrate adsorption isotherms of binary aqueous solutions of ethanol, n-propanol, and n-butanol. Excess surface is obtained by the derivative of surface tension taken with respect to alcohol activity, after this activity calculation using van Laar equation. Laboratory class contents are surface tension, excess surface, percolation of hydrogen bonds, micelle, activity, and ideal solution.

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The use of microwave in chemistry has known benefits over conventional heating methods, e.g. reduced reaction times, chemical yield improvement and the possibility if reducing or eliminating the use of organic solvents. We describe herein a procedure for the nitration of salicylaldehyde in water using a domestic microwave oven, which can be used as an experiment in the undergraduate chemistry laboratory. The experiment involves safe and rapid preparation and identification of the position isomers by thin layer chromatography and 1H NMR, or by their melting points.

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The Michaelis-Menten equation is used in many biochemical and bioinorganic kinetic studies involving homogeneous catalysis. Otherwise, it is known that determination of Michaelis-Menten parameters K M, Vmax, and k cat by the well-known Lineweaver-Burk double reciprocal linear equation does not produce the best values for these parameters. In this paper we present a discussion on different linear equations which can be used to calculate these parameters and we compare their results with the values obtained by the more reliable nonlinear least-square fit.

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Atmospheric chemistry in Brazil from 1790 to 1853. Scarcely any mention is made today of investigations carried out in Brazil during the period above on the science of the atmosphere. Yet the study of these cases reveals much about the milieu of a few devoted men who laboured to pursue a scientific career. That such an arcane topic has been the concern of investigators at such an early date may come as a surprise to many. The subject was an oddity as a field of study anywhere at the time, and its history deserves the attention of present-day chemists.

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Convinced that the " true balsam" was lost forever, Conrad Gesner described other substances with similar healing virtues. However, he was not the only one in the 16th to search for other varieties of balsamic oleoresins. The arrival of the Europeans to the Americas allowed the finding of native plants with properties similar to those of the original balsam, including Balsam of Peru, Balsam of Tolu and particularly in the Brazilian area, Balsam of Copaiba. Focusing on the Brazilian context, this paper analyzes two different moments in the transit of the newly found varieties of balsams to the pharmacopeia and materia medica.