Scielo RSS <![CDATA[Journal of the Chilean Chemical Society]]> http://www.scielo.cl/rss.php?pid=0717-970720160001&lang=en vol. 61 num. 1 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.cl/img/en/fbpelogp.gif http://www.scielo.cl <![CDATA[<strong>ARSENIC SORPTION USING MIXTURES OF ION EXCHANGE RESINS CONTAINING N-METHYL-D-GLUCAMINE AND QUATERNARY AMMONIUM GROUPS</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100001&lng=en&nrm=iso&tlng=en The method of synthesis and the arsenie removal properties of ion-exehange resins based on N-methyl-D-glueamine and trimethylammonium groups are presented. The N-methyl-D-glueamine based monomer was synthesized by the reaetion of 4-vinyl benzyl ehloride with N-methyl-D-glueamine, along with theuse of N,N-methylene-bis-aerylamide as a erosslinker reagent for polymerization. In addition, poly(4-vinylbenzyl)trimethylammonium was synthesized. Arsenatesorption studies were conducted and the pH effect, kinetics, sorption capacity, and elution performance were studied. The experimental data were fitted to kineticmodels, such as the pseudo-first order and pseudo-second order models. The pseudo-second order model exhibited the best correlation with the experimental data.The Langmuir and Freundlich isotherms were fitted to the experimental data, and the Freundlich isotherm exhibited the best fit. <![CDATA[<strong>CHEMISTRY LEARNING WITH APPLICATION OF THE ZONE OF PROXIMAL DEVELOPMENT AND USE OF CONCEPTUAL MAPS IN THE CHEMISTRY LAB</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100002&lng=en&nrm=iso&tlng=en The present study focuses on the deficient learning of health science students in the General Chemistry course in the first level higher education, specifically regarding the topic of aqueous dissolutions in terms of the meaning of pH and how to determine it. The causes of this problem are: i) the difficulty relating the theory to the practice, ii) the lack of strategies that help and motivate learning, iii) the inability to underst and and resolve problems or exercises, and iv) a deficiencyon basic mathematical aptitudes for application in resolving problems and exercises, among others. The research considered the academic results obtained bystudents of various careers in the area of health sciences students in the past, to subsequently determine the research group, resulting it the career of nursingstudents. To achieve this type of learning, the Zone of Proximal Development (ZPD) was applied, together with the metacognitive strategy of Conceptual Maps (CM) and feedback & self-correction in practical laboratory activities. This study was carried out at a university and involved nursing students because they havemany difficulties learning experimental sciences, especially chemistry, because the students of other careers do not have many weaknesses in this science, beingevidenced in the results at end of the semester-The sample experimental group consisted of 336 nursing students and the control group 420 students of nutrition and dietetics and dentistry taking the unit "General Chemistry", who provided all the information for this study. <![CDATA[<strong>FAST AND RELIADLE METHOD FOR MONITORING EPOXIDATION REACTION IN RECYCLED VEGETABLE OILS (ERVO) USING FTIR-ATR TECHNIQUE</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100003&lng=en&nrm=iso&tlng=en The present study focuses on the deficient learning of health science students in the General Chemistry course in the first level higher education, specifically regarding the topic of aqueous dissolutions in terms of the meaning of pH and how to determine it. The causes of this problem are: i) the difficulty relating the theory to the practice, ii) the lack of strategies that help and motivate learning, iii) the inability to underst and and resolve problems or exercises, and iv) a deficiencyon basic mathematical aptitudes for application in resolving problems and exercises, among others. The research considered the academic results obtained bystudents of various careers in the area of health sciences students in the past, to subsequently determine the research group, resulting it the career of nursingstudents. To achieve this type of learning, the Zone of Proximal Development (ZPD) was applied, together with the metacognitive strategy of Conceptual Maps (CM) and feedback & self-correction in practical laboratory activities. This study was carried out at a university and involved nursing students because they havemany difficulties learning experimental sciences, especially chemistry, because the students of other careers do not have many weaknesses in this science, beingevidenced in the results at end of the semester-The sample experimental group consisted of 336 nursing students and the control group 420 students of nutrition and dietetics and dentistry taking the unit "General Chemistry", who provided all the information for this study. <![CDATA[<strong>PREPARATION OF BORIC ACID MODIFIED EXPANDABLE GRAPHITE AND ITS INFLUENCE ON POLYETHYLENE COMBUSTION CHARACTERISTICS</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100004&lng=en&nrm=iso&tlng=en A boric acid modified expandable graphite (EG B) was prepared through oxidizing-intercalating reaction of natural graphite, using H2SO4 and boric acid (H3BO3) as intercalators simultaneously. The dilatability of the intercalated products were characterized with expansion volume and initial expansion temperature.Scanning electron microscope, X-ray diffraction spectroscopy, energy dispersive spectroscopy and Fourier transform infrared spectroscopy were employed todetect its layer structure, main element relative contents and function group. At the same time, its influence on combustion characteristics and thermal stability forlinear low density polyethylene (LLDPE) were investigated in limiting oxygen index (LOI) tests, vertical burning tests and thermal gravimetric/differential thermal gravimetric analyses. Comparing with the normal expandable graphite (EG, intercalated by single H2SO4), EGb exhibited high dilatability, thermal stability and flame retardancy for LLDPE. It had been testified by combustion tests that the addition of 30 wt % EGb to LLDPE improved the limiting oxygen index (LOI) from17.6% to 30.2%, and the vertical burning level of UL-94 standard reached V-0 level. Whereas, the LOI of the same amount referenced EG was only 25.1%, the UL-94 level only reached V-1. Moreover, the synergistic effect between EGb and ammonium polyphosphate (II) (APP) improved the LOI of 70LLDPE/10APP/20EGb composite to 33.0%, and the UL-94 level to V-0. The synergistic efficiency was attributed to the formation of continuous and compact residual char. <![CDATA[<strong>LIQUID CHROMATOGRAPHIC DETERMINATION OF SOLIFENACIN SUCCINATE, FLAVOXATE HYDROCHLORIDE AND TOLTERODINE TARTRATE IN BULK DRUGS AND THEIR PHARMACEUTICAL DOSAGE FORMS</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100005&lng=en&nrm=iso&tlng=en A simple, precise, specific and accurate reversed phase HPLC (RP-HPLC) method has been developed for the determination of solifenacin succinate (SOLS), flavoxate HC1 (FLXHC) and toltoridine tartarate (TOLT) in bulk and pharmaceutical dosage forms. The proposed RP-HPLC method was carried out using XterraRP-18 column (5 μm practical size, 25 cm x 4.6 mm i.d.). The flow rate, the injection volume and the detection wavelength were 1.0 μL/min, 20 μL and 200 nm, respectively. The mobile phase consisted of 0.05 M pentane sulfonic acid sodium salt (SOLS: pH 3.0±0.05, FLXHC and TOLT: pH 5.5±0.05) and acetonitrile (50:50 v/v). The retention times for SOLS, FLXHC and TOLT drugs were found to be 4.1±0.1 min, 4.3±0.0 min and 5.8±0.1 min, respectively. The calibration was linear over the concentration range of 0.1-100 μg/μL. The mean recoveries for SOLS, FLXHC and TOLT drugs were about 99.80%, 100.43% and 100.00%, respectively. The method was validated according to the ICH guidelines with respect to specificity, linearity, accuracy, precision and robustness. <![CDATA[<strong>ABSOLUTE CONFIGURATION ASSIGNMENT IN RACEMIC </strong><em><b>trans</b></em><strong>-STILBENE OXIDE USING CHIRAL LIQUID CHROMATOGRAPHY WITH COMBINED CHIROPTICAL DETECTION AND TIME-DEPENDENT DENSITY FUNCTIONAL THEORY CALCULATIONS</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100006&lng=en&nrm=iso&tlng=en A chiral chromatographic analysis using HPLC coupled in series with circular dichroism and optical rotation detectors (HPLC-CD-OR) was applied to racemic trans-stilbene oxide, allowing the on-line measurement of the CD spectra and [α] values for both enantiomers in the sample. These measurementsused the Gaussian peak model to estimate the concentration of each isomer in the CD and OR cells. Moreover, time-dependent density functional theory (TD-DFT) calculations at the B3LYP/TZVP//B3LYP/VDZ(P) and B3LYP/aug-cc-pVDZ//B3LYP/VDZ(P) levels of the ory for CD and OR, respectively, permitted the prediction of both chiroptical properties for each isomer, which in turn could be compared with the corresponding experimental data. In this case, the calculationswere consistent in predicting the correct combination of experimental CD bands and [a] sign and the refore facilitated the absolute configuration (AC) assignment of the optical isomers. The AC proposed using this methodology was in agreement with independent AC assignments in the literature. <![CDATA[<strong>SiO<sub>2</sub>@FeSO<sub>4</sub> NANO COMPOSITE AS NANOCATALYST FOR THE GREEN SYNTHESIS 1,1-DIACETATES FROM ALDEHYDES UNDER SOLVENT-FREE CONDITIONS</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100007&lng=en&nrm=iso&tlng=en Aldehydes compounds selective converted to 1,1-diacetates as protective reagent with SiO2@FeSO4 nano composite as effective nano catalyst at room temperature under solvent-free condition and acetic anhydride (Ac2O) as acetylation reagent. This method provides several advantages, such as low cost of the nano catalyst, high yields, short reaction time, chemoselective protection of aldehydes and operational simplicity. Aromatic and aliphatic, simple and conjugatedaldehydes were protected with excellent yields. In addition, chemoselective reductive acetylation of aldehydes over ketones was achieved perfectly with the reagent at room temperature. <![CDATA[<strong>BRANCHED POLYESTERS FROM GERMYLATED AND FATTY COMPOUNDS</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100008&lng=en&nrm=iso&tlng=en Here we report the synthesis of news branched polyesters derived from the trans-esterification reactions at modérate temperatures (140-190°C), either from polyglycols with different molecular weights and monomers such as germylated fatty tri-esters, or from dimethyl terephtalate and germylated fatty tri-alcohol.The structure of the resulting polymers was determined by elemental analysis, FTIR, and 13C CP MAS NMR, and their thermal properties by the rmogravimetry analysis and differential scanning calorimetry. 13C CP MAS NMR analysis indicates that the characteristic signals due to the methoxy groups of the germylatedfatty tri-ester and the CH2OH group of germylated fatty tri-alcohol completely disappeared. This suggests that the trans-esterification process reached a nearlycomplete conversion. All germylated branched polyesters are insoluble in classic organic solvents due to their polydimensional structure. Thermal properties of these new materials showed that they do not present any cristallinity phase, and undergo thermal decomposition above 300°C. <![CDATA[<strong>SYNTHESIS AND ANTIMICROBIAL EVALUATION OF SOME NEW ASYMMETRICALLY SUBSTITUTED 4-ARYL- 2,6-DI(COUMARINYL) PYRIDINES</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100009&lng=en&nrm=iso&tlng=en In the present work the synthesis of various 4-aryl-2-(coumarin-3-yl)-6-(4-methyl-3-phenyl coumarin-6-yl)pyridines (6a-i) and 4-aryl-2-(coumarin-3-yl)-6-(4-methyl-7-methoxy coumarin-8-yl)pyridines (7a-i) have been carried out by reacting 1-[2(H)-1-benzopyran-3-yl]-3-aryl-prop-2-en-1-ones (coumarinoyl chalcones) (3a-f) with appropriate coumarinoyl methyl pyridinium bromide salt 4 and 5 respectively. The target compounds were characterized by the IR,J H-NMR, 13C-APT and mass spectral analysis. Preliminary examination of target compounds as antimicrobial agents has been carried out using Broth dilutionmethod. <![CDATA[<strong><i>HYDROXYCINNAMIC ACID DERIVATIVES AND FLAVONOL PROFILES OF MAQUI (Aristotelia chilensis) FRUITS</i></strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100010&lng=en&nrm=iso&tlng=en Maqui (Aristotelia chilensis) is an edible berry native to Southern Chile. The anthocyanin profiles and concentrations of this fruit have been widely studied. The high concentration of anthocyanins confers a deep colour to the skin and pulp of maqui berries, and the biological activity of this fruit has been attributed to these compounds. However, other compounds such as flavonols and hydroxycinnamic acid derivatives in this fruit have not been studied to date. The objective was to determine the hydroxycinnamic acid derivatives and flavonol profiles in maqui berries in order expand the knowledge base for this fruit. Two extraction methodologies (solid phase extraction using a mixed mode cation exchange cartridge and selective precipitation), followed by HPLC-DAD-ESI-MS/MS were applied to the extraction and identification of the main hydroxycinnamic acids and flavonols in the berries. Quantification was accomplished by using the first extraction procedure. Low levels of hydroxycinnamic acid derivatives were detected in maqui berries, where 5-galloylquinic acid was the only quantifiable derivative. However, diverse and high levels of flavonols were detected in the fruit, the most relevant of which are myricetin-galactoside, quercetin-rutinoside, and quercetin-3-galactoside. Nineteen other flavonols were identified, with total concentrations between 1.05 and 1.18 μmol/g fresh weight. The diversity of flavonols makes the profiles and concentrations of these compounds significant, whereas hydroxycinnamic acids in maqui are not significan! The comparatively high levels of flavonols combined with the high concentration of anthocyanins contribute to the consideration of this native fruit from Chileas a "superfruit". <![CDATA[<strong>HEAVY METAL CONCENTRATIONS IN WATER AND SEDIMENTS FROM AFFLUENTS AND EFFLUENTS OF MEDITERRANEAN CHILEAN RESERVOIRS</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100011&lng=en&nrm=iso&tlng=en RIVER flows have constant interaction between water and bed sediments; for this reason knowledge of the characteristics of the sediments is fundamental to understand water chemistry. This study determined the concentrations of heavy metals in water and sediments in the affluents and the effluents of the MediterraneanChilean reservoirs Cogotí, Corrales, La Paloma, and Recoleta. We explore possible ecological risk and toxicity using the enrichment factor (EF), risk assessmentcode (RAC), threshold effect concentrations (TEC) and probable effect concentrations (PEC). The results showed that five metals: Al, Fe, Cu, Mn and Zn out of the ten measured metals were detected in both surface water and the sediments. The risk assessment code (RAC) suggested that Fe represents a medium risk in the affluent of Cogotí Reservoir: Cu, Zn and Mn represent a medium to high risk in all the dams and in both zones (affluents and effluents). The enrichment factor(EF) determined that the five metals were lithogenic. Fe, Cu, and Mn are the elements that present the greatest toxicity to microorganisms in these aquatic systems. <![CDATA[<strong>CHEMICAL CHARACTERIZATION OF SUB-BITUMINOUS COAL FROM THE ARAUCO PROVINCE - CHILE</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100012&lng=en&nrm=iso&tlng=en The chemical and sorptive characteristics of mineral coals extracted from a mine in Lebu (Biobío Región, Chile) and its derivatives were studied. These derivatives were obtained by applying a thermal treatment in an environment with N2 and CO2 at different experimental conditions, in order to increase their specific surface. In addition, coals were characterized by using proximal analysis, elementary analysis and petrographic analysis. In order to know their structureand surface, Boehm titration analysis, FTIR infrared spectroscopy, X-ray diffraction and scanning electron microscopy were performed. The surface of the selectedcarbons was modified by selectively oxidizing it with (NH^S^O and with H2O2 e impregnating with an iron solution for the study with H2O2 In the oxidation ofH2O2, the work was carried out at different pH. The results show a moderate homogeneity between different types of seams studied, whereas when coals are treatedwith heat or strong oxidants, increases its surface and can be used with analytical applications (v.g. electroanalytical sensors). <![CDATA[<strong>TEMPERATURE EFFECT ON BINDING AFFINITY AND STOICHIOMETRY BETWEEN SOME STEROIDS AND HUMAN SERUM ALBUMIN</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100013&lng=en&nrm=iso&tlng=en The temperature dependence of the interactions between some steroids (fusidic acid, ouabain and ethynodioldiacetate) and human serum albumin (HSA) at physiological pH (7.4) were studied systematically by square-wave voltammetry. Also, these interactions were proven by means of UV-Vis. absorptionspectroscopy and FT-IR spectroscopy techniques. The interaction parameters (binding constants and stoichiometries) at temperature range of 297.5-312.5 K weredetermined from electrochemical data. It is worthy that the temperature has played a positive role on the interactions of fusidic acid with HSA; however it hasnegative effective on the interaction parameters of HSA with ouabain or ethynodioldiacetate. <![CDATA[<strong>MOLYBDENUM TRIOXIDE THIN FILMS DOPED WITH GOLD NANOPARTICLES GROWN BY A SEQUENTIAL METHODOLOGY: PHOTOCHEMICAL METAL-ORGANIC DEPOSITION (PMOD) AND DC-MAGNETRON</strong> <strong>SPUTTERING</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100014&lng=en&nrm=iso&tlng=en Gold nanoparticles (AuNPs) were deposited by DC-magnetron sputtering onto molybdenum trioxide (MoO3) thin films grown by Photochemical Metal-Organic Deposition (PMOD) on Si(100) and borosilicate glass substrates. The chemical, optical and morphology properties of the films were studied by UV/ Vis Spectroscopy, Scanning Electron Microscopy (SEM), X-Ray Photoelectron Spectroscopy (XPS), and X-Ray Diffraction (XRD). SEM revealed that AuNPs formed after 5 s of sputtering. AuNPs are spherical and have both an average diameter of 18 nm and a relatively narrow size distribution. As the deposition time increases, larger structures are formed by an aggregation of AuNPs. XPS studies of the AuNP/MoO3 films on Si(100) showed the presence of Mo(VI) and Mo(V), which indicated that the films were primarily non-stoichiometric molybdenum oxides. The occurrence of oxygen vacancies in the substrate play an important role to stabilize the AuNPs. <![CDATA[<strong>NEW PHOSPHORUS COMPOUNDS K[PCL<sub>3</sub>(X)] (X= SCN, CN)</strong>: <strong>PREPARATION AND DFT AND SPECTROSCOPIC STUDIES</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100015&lng=en&nrm=iso&tlng=en Two new phosphorus complexes, potassium trichlorothiocyanophosphate (III) (PTCTCP; K[PCl3(SCN)]) and potassium trichlorocyanophosphate (III) (PTCCP; K[PCl3(CN)]) were synthesized from the reaction of KSCN and KCN, respectively, with PC^. The chemical formulas and compositions of these compounds were determined by elemental analysis and spectroscopic methods, such as phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy (31P-NMR), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy and mass spectrophotometry. All of the theoretical calculations and determinations of the properties of these compounds were performed as part of the Amsterdam Density Functional (ADF) program. Excitation energies were assessed using time-dependent perturbation density functional theory (TD-DFT). In addition, the molecular geometry was optimized and the frequencies and excitation energies were calculated using standard Slater-type orbital (STO) basis sets with triple-zeta quality double plus polarization functions (TZ2P) for all of the atoms. The assignment of the principal transitions and total densities of state (TDOS) for orbital analysis were performed using the GaussSum 2.2 program. <![CDATA[<strong>PHENOLIC COMPOSITION AND BIOLOGICAL (ANTI DIABETIC AND ANTIOXIDANT) ACTIVITIES OF DIFFERENT SOLVENT EXTRACTS OF AN ENDEMIC PLANT (HELIOTROPIUM STRIGOSUM)</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100016&lng=en&nrm=iso&tlng=en Heliotropium strigosum plant is widely used in traditional medicines for treatment of various ailments. In current study, an effort was made to evalúate phenolic profile as well as antidiabetic and antioxidant activities of crude methanol extract and different solvent (n-hexane, ethyl acetate, chloroform and aqueous) fractions of H. strigosum. Total phenolic contents were determined by spectrophotometric assay. Polyphenolic compounds in crude methanol extract and each solvent fraction were identified by reverse phase high performance liquid chromatography (RP-HPLC). Antioxidant and antidiabetic activities were determined using DPPH and a-amylase inhibition assays, respectively. The outcome of spectrophotometric assay showed that methanol extract had higher amount of total phenolic (84.50 ± 0.06 pg GAE/ mg of plant extract) contents than aqueous, ethyl acetate, chloroform and n-hexane fractions, respectively. The RP-HPLC analysis revealed the maximum number of phenolic (chromotropic acid, quercetin, trans-4-hydroxy-3-methoxy cinnamic acid, vanillic acid, gallic acid, caffeic acid, m-coumaric acid, p-coumaric acid, syringic acid, sinapic acid and ferulic acid) compounds in methanol extract. Methanol extract (IC5(0) = 8.97 pg/mL) exhibited the maximum antidiabetic activity followed by aqueous (IC50 = 20.04 pg/mL), ethyl acetate (IC50 = 27.79 pg/mL), chloroform (IC50 = 56.87 pg/mL) and hexane (IC50 = 32.16 pg/mL) fractions, respectively. The outcome of antioxidant assay revealed that methanol extract was the leading one with regard to antioxidant activity at different doses (10 to 250 pg/mL). The current study concludes that H. strigosum solvents extracts with significant phenolic profile and potent biological activities could be explored for potential uses in neutraceutical and pharmaceutical industries. <![CDATA[<strong>STUDY OF THE REMOVAL OF 4-NITROPHENOL FROM AQUEOUS MEDIA BY ADSORPTION ON DIFFERENT MATERIALS</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100017&lng=en&nrm=iso&tlng=en The removal of 4-Nitrophenol (4-NP) from aqueous media by adsorption is studied in a batch system using different porous materiais: activated carbón, zirconia, alumina, sepiolite, natural zeolite and 13X zeolite. Depending on their adsorption capacities, the best adsorbent was chosen to be impregnated withdifferent levels of nickel (Ni) in order to study the adsorption by n-complexation in batch and continuous systems. The samples of Ni(x)/support (x= 2, 4, 6%)were prepared by wet impregnation and were characterised using the same method as with all the materials, by N2 adsorption-desorption using the BET method,surface acidity and Z potential measurements by electrophoretic migration. The samples were measured in a UV-Vis electrophotometer at a wavelength of 318nm, while the adsorption capacity of the material in the batch system was determined by calculating the difference in concentration once the adsorbent becamesaturated after an initial concentration of ~20 ppm, and in the continuous system this was done by integrating the area under the adsorption curve. The resultssuggest that adsorption capacity depends on the specific BET area, apparent acid strength and the IEP of each support, and that it varies with the addition of Ni. <![CDATA[<strong>DEVELOPMENT OF AN ANALYTICAL METHOD FOR THE MAIN ORGANIC COMPOUNDS DERIVED FROM THERMOCHEMICAL CONVERSION OF BIOMASS</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100018&lng=en&nrm=iso&tlng=en In this work, high-performance liquid chromatography (HPLC-UV/RID) is applied to the simultaneous determination of acetic acid, formic acid, acetol, glyoxal, glycolaldehyde and levoglucosan in a by-product in an aqueous liquid phase that is produced by the Hydrothermal Carbonization (HTC) process and inan aqueous bio-oil phase, which comes from a fast pyrolysis process. Both processes were run in forest biomass. For the development and optimization of the proposed method, some chromatographic columns were evaluated based on separation principles of reversed phase and ionic exclusion, although it was previously performed with a solid phase extraction (SPE) process. Concentrations of acetic and formic acids in the liquids of the HTC process ranged from 0.26 to 1.5 % and from 0.14 to 2.7 %, respectively. Concentrations of acetic and formic acids, levoglucosan and glycolaldehyde in the aqueous bio-oil phases ranged from 0.4 - 4.6 %, 0.4 - 1.4 %, 0.13 - 2.5 % and 0.5 - 3.5%, respectively. <![CDATA[<strong>RECYCLABLE ACIDIC BR0NSTED IONIC LIQUID CATALYZED SYNTHESIS OF QUINOXALINE</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100019&lng=en&nrm=iso&tlng=en The acidic ionic liquid, 1-(4-sulfonic acid) butyl-3-methylimidazolium hydrogen sulfate [MimC4SO3H]HSO4 catalyzed two-component condensation reaction of phenacyl bromide and o-phenylenediamine to afford corresponding quinoxaline derivatives. The inexpensive and non-toxic ionic liquids can be reused severaltimes without any perceptible loss of their activities. <![CDATA[<strong>SENSITIVE SIMULTANEOUS DETERMINATION OF PARACETAMOL AND DICLOFENAC BASED ON Au NANOPARTICLES - FUNCTIONALIZED GRAPHENE/POLY (L-ARGININE) GLASSY CARBON ELECTRODE</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072016000100020&lng=en&nrm=iso&tlng=en A voltammetric sensor was proposed for simultaneous determination of paracetamol and diclofenac based on poly (L-arginine)/Au-graphene nanocomposite film deposited on a glassy carbon electrode. Cyclic voltammetry showed that paracetamol and diclofenac provided well - defined oxidation peaks at +0.443 and +0.644 V, respectively. Experimental parameters, such as the concentration of L-arginine and number of potential cycles in electro-polymerization step,accumulation potential and time, and the pH of buffer solution were optimized. Under the optimized conditions, linear relationships between oxidation peak current and concentration in the range 0.5 - 50.0 pM for paracetamol, and 0.5 - 40.0 pM for diclofenac were obtained in linear sweep voltammetry regime. The limits of detection (LOD) for paracetamol and diclofenac were 0.04 and 0.08 pM, respectively. The fabricated electrode exhibited good reproducibility and stability.The proposed method was successfully applied to the assessment of low concentrations of paracetamol and diclofenac in spiked human blood serum samples withsatisfactory results.