Search

The role of α‐ and β‐d‐glucose, and d‐gluconate anion, acting as capping agent, on silver nanoparticles (AgNPs) was evaluated using both Raman and density functional theory studies. The particles were synthetized employing glucose, as reducing and blocking agent, in alkaline conditions. Capping agents were characterized through surface enhancement Raman spectroscopy together with modeling performed using silver clusters. Several geometries were optimized, and its energies and wavenumbers were calculated for each of them. Vibration normal modes from d‐glucose isomers and d‐gluconate were obtained and compared with those reported in bibliography, showing a satisfactory correlation. Comparison between experimental and calculated frequencies reveals a preference for d‐gluconate anion acting as capping agent under the necessary presence of d‐glucose on the surface of the AgNPs. The study of energies shows a greater affinity of d‐gluconate for the silver atoms (above −1.3 eV for both geometries) than for other configurations of the glucose molecule (about −0.66 eV in the case of α‐d‐glucose). Fil: González Fá, Alejandro Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina. Universidad Nacional del Sur. Departamento de Química; Argentina Fil: López Corral, Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Faccio, Ricardo Juan. Universidad de la República; Uruguay Fil: Juan, Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

A simple, rapid and non-expensive method is proposed to determine hypoxanthine (Hx), xanthine (Xa) and uric acid (UA) in untreated fish samples based on an edge plane pyrolytic graphite electrode (EPPGE). The square wave voltammetry was the electrochemical technique used. In addition, the experimental design and multi-response assays were used to optimize the pretreatment of the working electrode. Therefore, the EPPGE is used in the simultaneous determination of these analytes for the first time. The optimal accumulation conditions of the analytes on the surface of the working electrode were obtained through a composite central design. The linear range was from 0.1 to 50 μM for Hx and Xa, and from 0.1 to 25.0 μM for UA. The limits of detection (LOD) were 0.08, 0.06 and 0.03 μM for Hx, Xa and UA, respectively. Recovery assays were made in order to validate the proposed method. Recovery percentages were between 90 and 110%. Therefore, the method is a good, simple and fast option for the simultaneous determination of Hx, Xa and UA in fish samples, allowing to perform a control quality of samples.

The development of methodologies for the characterization of silver nanoparticles (AgNPs) synthesized using natural products has received increasing attention, especially to monitoring its stability and size for further application. In this paper, a capillary electrophoretic (CE) method is presented for characterization of AgNPs synthesized using honey or glucose as reducing agents. A simple electrolyte solution composed of 20 mM sodium borate and 20 mM sodium dodecylsulfate (SDS) at pH 8.5 was used for separation of AgNPs within a short analysis time (

The quantification of zinc in over-the–counter drugs as commercial propolis extracts by molecular fluorescence technique using meso-tetrakis(4-carboxyphenyl)porphyrin (H2TCPP4) was developed for the first time. The calibration curve is linear from 6.60 to 100 nmol L−1 of Zn2+. The detection and quantification limits were 6.22 nmol L−1 and 19.0 nmol L−1, respectively. The reproducibility and repeatability calculated as the percentage variation of slopes of seven calibration curves were 6.75% and 4.61%, respectively. Commercial propolis extract samples from four Brazilian states were analyzed and the results (0.329–0.797 mg/100 mL) obtained with this method are in good agreement with that obtained with the Atomic Absorption Spectroscopy (AAS) technique. The method is simple, fast, of low cost and allows the analysis of the samples without pretreatment. Moreover the major advantage is that Zn-porphyrin complex presents fluorescent characteristic promoting the selectivity and sensitivity of the method.

The main goal of this work is the application of an antimony film electrode (SbFE) prepared for thefirst time ?in-situ? to determine organic compound as tetracyclines commonly used in Argentine forhive treatment. The SbFE was prepared on a glassy carbon electrode (GCE) and square wave cathodicstripping voltammetry (SWCSV) technique was used. The SWCSV parameters were optimized based on aDraper Lin small composite design. The SWCSV response was linear in the TCs concentration range from0.40 to 3.00 uM with a limit of detection (LOD) of 0.15 uM. The proposed method is a good and simplealternative to the determination of tetracyclines in Argentinean honeys samples. Recovery experimentswere performed using spiked honey samples with standard deviation values from 0.75% and 9.69%. Fil: Krepper, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Pierini, Gastón Dario. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina Fil: Pistonesi, Marcelo Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

New materials based on V2O5, TeO2 and a combination of graphite, graphene oxide and multiwalled carbon nanotubes were developed and tested as potential electrochemical sensors. A mixture design with three components in combination with multi-response assays based on the desirability function was used as multivariate optimization for the system composition. The optimal sensor contains graphene oxide and multiwalled carbon in approximately equal amounts. The new sensors characterizations were performed with X-ray diffraction, differential scanning calorimetry, impedance spectroscopy and cyclic voltammetry. The main advantage of this electrodes are does not requires surface activation and exhibited a potential electroanalytical performance with different targeted analytes such as ascorbic acid, aspartame and lead. Fil: Pierini, Gastón Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Di Pratula, Pablo Emmanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Ochoa, Ana Laura. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina Fil: Centurión, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

In this work, we made a review about the application of Raman spectroscopy for quality control of honey and other food samples. Simultaneously, it was carried out a new research evaluating silver nanoparticles (AgNPs) obtained by green synthesis for detection of the antibiotic Oxytetracycline (OTC), through Surface Enhanced Raman Spectroscopy (SERS). Glucose was used as reducing and capping agent in the formation of AgNPs in alkaline media. The frequencies found, belonging to the antibiotic at 20, 15, 10 and 5 ppb, could be visibly differentiated from those corresponding to honey, being unnecessary to perform any extraction procedure or tedious manipulation of the sample. Theoretical frequencies were obtained by Density Functional Theory calculations and compared with the normal modes from SERS measures, founding an excellent agreement between them. The analysis shows a preference for the adsorption of OTC on silver cluster through oxygen atoms. Fil: González Fá, Alejandro Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Pignanelli, Fernando. Universidad de la República; Uruguay Fil: López Corral, Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Faccio Sgiorovello, Ricardo Juan. Universidad de la República; Uruguay Fil: Juan, Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

The main goal of this work is the development of an electroanalytical method for the amitraz determination in honey samples by quantification its final metabolite, 2,4 dimethylaniline. An electrochemically activated glassy carbon electrode (AGCE) as working electrode and adsorptive square wave voltammetry (ASWV) technique were used. A simple and fast microwave-assisted pretreatment of the samples was presented to accelerate the amitraz hydrolysis to 75 s. The ASWV parameters were optimized based on a “Box-Benkhen” design. The ASWV response was linear in the hydrolyzed amitraz concentration range from 0.25 to 2.50 μM with a limit of detection (LOD) of 0.19 μM. The proposed method is a simple and low-cost alternative for the determination of amitraz residues in Argentine honeys samples. Recovery experiments were performed using spiked honey samples with recoveries from 91.41 to 108.6%. Fil: Krepper, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina Fil: Pistonesi, Marcelo Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

We present for the first time a novel analytical method based on a model of three-way calibration using second-order data generated from the combination of records of forward (oxidation) and reverse (reduction) currents using a glassy carbon electrode modified with a dispersion of electrochemically reduced graphene oxide (GCE/RGO) as the working electrode, which can be obtained from a square wave voltammetry single experiment. This methodology was used for the simultaneous determination of ascorbic (AA) and uric (UA) acids, and dopamine (DO) in the presence de glucose (interfering species) in lyophilized human serum samples. The serum samples have analyte different concentration levels (normal and pathological levels). The forward and reverse currents were pre-processed using AsLS and COW, to generate the second order data and finally the data were modeled with the U-PLS algorithm. Recovery studies were made in order to validate the proposed method. Recovery percentages between 92.4 and 120% were obtained. The present method has the advantage to generate second order data through a simple voltammetric experiment. Among the advantages of the proposed method can be mentioned speed, easy data acquisition and the possibility of using modified electrodes with nano-structures. Fil: Granero, Adrian Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química y Física; Argentina Fil: Pierini, Gastón Dario. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química y Física; Argentina Fil: Robledo, Sebastian Noel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rio Cuarto. Facultad de Ingeniería. Departamento de Tecnología Química; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Fernandez, Hector. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química y Física; Argentina Fil: Zon, María Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química y Física; Argentina

Propolis is a hive product prepared by honeybees ( Apis mellifera L.) widely used in pharmaceutical and food preparations that plays beneficial roles beyond basic nutrition and therapeutic properties. These benefits are related with its quality, which depends on various factors, such as geographical origin, botanical sources, collecting seasons, races of honeybees, climatic conditions and also the method of harvest. In this sense, it would be helpful the implementation of a simple, fast and reliable analytical methodology for quality monitoring of propolis samples as a traceability tool of its geographical origin. Thus, this work proposes the use of digital images and chemometrics for the classification of raw propolis from six different geographical origins of the Buenos Aires Province, Argentina. For this purpose, different combinations between a color model (Grayscale, RGB and HSI) and a multivariate classifier (PCA–LDA, SIMCA, kNN, PLS-DA and SPA–LDA) were tested. The best analytical performance was achieved by SPA–LDA using Intensity histograms, classifying correctly a 100% of the samples in both training and test sets, taking in account the 27 variables selected by SPA. As a consequence, the proposed methodology serves to support local apiculturists, guaranteeing the offer of products with a clear indication of geographical origin, and enhancing regional capabilities.

Tryptamine, a biogenic amine, is an indole derivative with an electrophilic substituent at the C3 position of the pyrrole ring of the indole moiety. The electrochemical oxidation of tryptamine was investigated using glassy carbon electrode (GCE), and focusing on trace level determination in food products by square wave adsorptive stripping voltammetry (SWAdSV). The electrochemical responses of tryptamine were evaluated using differing voltammetric techniques over a wide pH range, a quasi-reversible electron-transfer to redox system represented by coupled peaks P1-P3, and an irreversible reaction for peak P2 were demonstrated. The proton and electron counts associated with the oxidation reactions were estimated. The nature of the mass transfer process was predominantly diffusion-limited for the oxidation process of P1, the most selective and sensitive analytical response (acetate buffer solution pH 5.3), being used for the development of SWAdSV method, under optimum conditions. The excellent response allowed the development of an electroanalytical method with a linear response range of from 4.7-54.5)×10(-)(8)molL(-1), low detection limit (0.8×10(-)(9)molL(-)(1)), and quantification limit (2.7×10(-9)molL(-1)), and acceptable levels of repeatability (3.6%), and reproducibility (3.8%). Tryptamine content was determined in bananas, tomatoes, cheese (mozzarella and gorgonzola), and cold meats (chicken sausage and pepperoni sausage), yielding recoveries above 90%, with excellent analytical performance using simple and low cost instrumentation.

Determining fat content in hamburgers is very important to minimize or control the negative effects of fat on human health, effects such as cardiovascular diseases and obesity, which are caused by the high consumption of saturated fatty acids and cholesterol. This study proposed an alternative analytical method based on Near Infrared Spectroscopy (NIR) and Successive Projections Algorithm for interval selection in Partial Least Squares regression (iSPA-PLS) for fat content determination in commercial chicken hamburgers. For this, 70 hamburger samples with a fat content ranging from 14.27 to 32.12 mg kg− 1 were prepared based on the upper limit recommended by the Argentinean Food Codex, which is 20% (w w− 1). NIR spectra were then recorded and then preprocessed by applying different approaches: base line correction, SNV, MSC, and Savitzky-Golay smoothing. For comparison, full-spectrum PLS and the Interval PLS are also used. The best performance for the prediction set was obtained for the first derivative Savitzky-Golay smoothing with a second-order polynomial and window size of 19 points, achieving a coefficient of correlation of 0.94, RMSEP of 1.59 mg kg− 1, REP of 7.69% and RPD of 3.02. The proposed methodology represents an excellent alternative to the conventional Soxhlet extraction method, since waste generation is avoided, yet without the use of either chemical reagents or solvents, which follows the primary principles of Green Chemistry. The new method was successfully applied to chicken hamburger analysis, and the results agreed with those with reference values at a 95% confidence level, making it very attractive for routine analysis. Fil: Krepper, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Romeo, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Fernandes, David Douglas de Sousa. Universidade Federal da Paraíba; Brasil Fil: Diniz, Paulo Henrique Gonçalves Dias. Universidade Federal do Oeste da Bahia; Brasil Fil: Araújo, Mário César Ugulino de. Universidade Federal da Paraíba; Brasil Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Pistonesi, Marcelo Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Centurión, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

Silver nanoparticles were synthesized using honey at pH 5.0 and 10.0 using a rapid, low cost, and simple technique. The influence of the honey carbohydrates (glucose and fructose) in the synthesis was characterized. Moreover, the kinetic variables in the synthesis at room temperature and at pH 5.0 and 10.0 were analyzed by measuring surface plasmon resonance at 411 nm by absorption spectroscopy. Transmission electron microscopy, thermal gravimetric analysis, and differential thermal analysis were used to characterize the metal nanoparticles and the capping agents. The synthesized nanoparticles were obtained for the first time at pH 5.0. This fact allows evaluating the kinetics and reaction mechanism. The obtained nanoparticles were spherical, monodispersed, and smaller than 20 nm. The results show that glucose serves as a reducing and capping agent while fructose has a limited reducing effect. Fil: González Fá, Alejandro Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Juan, Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

A low cost composite electrodes employing tellurite oxide, vanadium oxide and micrometric granular graphite (NWE), were designed as an alternative to be used as working electrode in voltammetry techniques. The synthesis of these composite electrodes is carried out easily; in a short time and their surface not require previous preparation. X-ray diffraction, X-ray fluorescence spectrometry and optical microscopy studies were used to determine the morphology and chemical composition of these electrodes. The conductivity characterization was conducted with impedance and electrochemical measurements. The electrochemical properties of NWE were studied using potassium hexacyanoferrate (II) and ascorbic acid system. Fil: Pierini, Gastón Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Presa, Jimena Mailén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Centurión, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

Raw propolis and bee pollen has been widely used in different areas such as medicine, food and apitherapy because they have biological and medicinal properties. The beneficial effects of both bee products for human health include antibacterial, antiviral, antimicrobial and anti-inflammatory properties. However, hives exposure to heavy metals, due beekeeping practices and environment, is one of the problems facing beekeepers. The presence of cadmium in bee products should be controlled, because of its high toxicity. A lab-made Bismuth Bulk Electrode (BiBE) was developed for cadmium residue determination in Argentinean bee products such as raw propolis and bee pollen employing square wave anodic stripping voltammetry (SWASV) as electrochemical technique. The SWASV parameters were optimised based on a 2 5 factorial design. The method presents a linear range from 2.00 to 100.0 µg L−1 of Cd (II) with a limit of detection (LOD) and a limit of quantitation (LOQ) of 0.78 µg L−1 and 2.61 µg L−1, respectively. The repeatability was 8.03%, calculated as the relative standard deviation. Recovery experiments were performed using spiked raw propolis and bee pollen samples with standard deviation values from 1.16% to 7.20%. The BiBE is easy and fast to elaborate and the propose method is environmentally friendly and low cost. Then, it can be considered as a good alternative to the quality control of bee products due to its importance in the beekeeping industry. Fil: Krepper, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Resende de Cerqueira, Paula B.. Universidade Federal de Minas Gerais; Brasil Fil: Pistonesi, Marcelo Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Centurión, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

A simultaneous determination of Zn, Cd, Pb and Cu in raw propolis samples, employing square wave anodic stripping voltammetry and chemometric tools, was developed. For this purpose, a pencil-lead bismuth film electrode was used as a working electrode. In order to optimize the parameters of square wave voltammetry a Box-Behnken design combined with desirability function was used. Different algorithms such Asymmetric Least Squares (AsLS) and Correlation Optimized Warping (COW) were employed in order to preprocess the raw data. Partial Least Squares (PLS) and Artificial Neuron Networks (ANN) were used to predict the concentration of the four metals in the samples. The method was tested successfully on raw propolis samples obtained from different localities of the Province of Buenos Aires, Argentina and the results were validated with recovery assays. Fil: Pierini, Gastón Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Pistonesi, Marcelo Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Centurión, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

A direct spectrophotometric method for the determination of three artificial colors - amaranth, sunset yellow FCF and tartrazine - in beverages samples is proposed. The spectra were recorded between 359 and 600 nm. The spectra of the samples (just filtrated), pure dyes (concentrations ranged between 0.01 and 1.8 mg L-1 for amaranth, 0.08 and 4.4 mg L-1 for sunset yellow and 0.04 and 1.8 mg L-1 for tartrazine) and synthetic mixtures were disposed in a column-wise augmented data matrix. This kind of data structure, analyzed by multivariate curve resolution-alternating least squares (MCR-ALS) makes it possible to exploit the so called 'second order advantage'. MCR-ALS algorithm was applied to the experimental data under the non-negativity and equality constraints. As a result, the concentration of each dye in the samples and their corresponding pure spectra were obtained. The results were validated using internal reference materials and no significant differences were found (α = 5%) between the reference values and the ones obtained with the proposed method. The second order advantage made it possible to obtain unbiased results even in the presence of interferences. Fil: Llamas, Natalia Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Garrido, Mariano Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Fernández Band, Beatriz Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

A simple and rapid analytical procedure for determination of saccharin (SAC) and acesulfame-K (AC-K) based on UV-vis measurements and partial least squares (PLS) was proposed. Thus, an experimental design at levels 2 and 15 mg l−1 for SAC and 2 and 20 mg l−1 for AC-K was applied. Because real samples usually contain SAC and AC-K combined with aspartame (ASP), this interference was also included in the model. The procedure was successfully applied for SAC and AC-K simultaneous determination in sweeteners and fruit juice powders, without any separation step to remove ASP. The results were validated by using spiked samples, and the obtained recoveries were satisfactory.

A multi‐element flow injection (FI) system with spectrophotometric detection was developed for sequential determination of Zn(II), Cu(II), Cd(II), Pb(II), and Hg(II). Dithizone reagent was used for the previously mentioned analytes and it was prepared on line by using a solid reagent column (SRC). Bear in mind that the most hazardous elements for environmental contamination are lead, cadmium, and mercury; a multi‐element FI system with preconcentration steps is proposed to determine their trace levels in natural waters. Results obtained for different samples agreed satisfactorily with those obtained by the reference method inductively coupled plasma‐atomic emission spectrometry (ICP‐AES). Detection limits were 5.4, 5.0 and 14 µg L−1 for Cd(II), Pb(II), and Hg(II), respectively. The percent of relative standard deviation (RSD) was better than 4.5% for each one.

A flow injection turbidimetric method for determination of cyclamate in low calorie soft drinks and sweeteners without pre-treatment is proposed. It was based on the oxidation of the sulphamic group of cyclamate, to sulphate by addition of nitrite. Then, a precipitate of sulphate was obtained by reaction with barium chloride, in presence of poly(vinyl alcohol) (PVA) in perchloric acid solution, at 30°C. The analytical signal was measured at 420 nm. The method presented a linear range between 0.015 and 0.120% (w/v) and the calibration graph was S = (7.792 ± 0.179) X - (0.114 ± 0.012), R2 = 0.999. A reproducibility of 5.9% was obtained from nine calibration graphs that were carried out on different days and with different conditions (standard solution, reagents solution, etc.). The detection and quantification limits were 0.006 and 0.02% (w/v), respectively, the sample throughput 45 h-1 (by considering the wash cycle and the time consuming to eliminate the clean solution from the system). The obtained results were agreement with that obtained with the standard method. Fil: Llamas, Natalia Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Fernández Band, Beatriz Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

Model networks were prepared by the reaction of monodisperse polybutadiene, containing 8% of double bonds in the 1,2 vinyl position, with p-bis(dimethyl silyl) benzene at different stoichiometric imbalances. Small strain modulus and measurements of the gel fraction indicate important differences with the predictions from ideal network forming reactions and the molecular theories of rubberlike elasticity. Sol extractions are higher than expected and small strain moduli are consistently low. Other macroscopic signs of the departure from ideal behaviour are detected. The onset of the gel point is delayed to a degree that grows with increasing imbalance of the reactive groups. We consider all the possible explanations for the observed behaviour, and suggest that the most likely one is the presence of intramolecular reaction. We also propose a simple theoretical model to confirm that our assumptions are consistent with the experimental results.

In this paper a geographic origin classification of honey samples from Argentina was proposed. For this reason, a conventional flow-batch system with a simple webcam to capture digital images was employed. In this methodology, analytical information is generated from color histograms obtained from the digital images employing different color models (RGB (red-green-blue), HSB (hue-saturation-brightness) and Grayscale). Three chemometric tools were employed for geographic origin classification (SPA-LDA (successive projections algorithm-linear discriminant analysis), SIMCA (soft independent modeling for class analogy), and PLS-DA (partial least squares-discriminant analysis)). The proposedmethod is a good option to be used in quality control laboratories for the classification of honey samples according to their geographical origin. Fil: Dominguez, Marina Alejandra. Universidad Nacional del Sur. Departamento de Quimica. Quimica Analitica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina Fil: Gonçalves Dias Diniz, Paulo Henrique . Universidade Federal da Paraiba; Brasil Fil: Di Nezio, Maria Susana. Universidad Nacional del Sur. Departamento de Quimica. Quimica Analitica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina Fil: Ugulino de Araújo, Mário César . Universidade Federal da Paraiba; Brasil Fil: Centurión, María Eugenia. Universidad Nacional del Sur. Departamento de Quimica. Quimica Analitica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina

An automatic flow-batch system that includes two borosilicate glass chambers to perform sample digestion and cold vapor atomic absorption spectroscopy determination of mercury in honey samples was designed. The sample digestion was performed by using a low-cost halogen lamp to obtain the optimum temperature. Optimization of the digestion procedure was done using a Box-Behnken experimental design. A linear response was observed from 2.30 to 11.20 μg Hg L-1. The relative standard deviation was 3.20% (n = 11, 6.81 μg Hg L-1), the sample throughput was 4 sample h -1, and the detection limit was 0.68 μg Hg L-1. The obtained results with the flow-batch method are in good agreement with those obtained with the reference method. The flow-batch system is simple, allows the use of both chambers simultaneously, is seen as a promising methodology for achieving green chemistry goals, and is a good proposal to improving the quality control of honey. Fil: Dominguez, Marina Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Grunhut, Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Pistonesi, Marcelo Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Centurión, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

Propolis is a honeybee product which contains lead as one of the main contaminants. Taking into account that this product is used in the food industry, the Código Alimentario Argentino establishes maximum allowable level for raw propolis. Therefore, in this study an electroanalytical method to determine this metal in Argentina raw propolis samples was developed. A bismuth film electrode plated on a modified glassy carbon electrode was prepared. The use of these electrodes has been proposed as an alternative to mercury film electrodes in electroanalytical chemistry due to low toxicity of bismuth (environmentally friendly metal). The method presents a linear range between 1 and 50 μg L− 1 of Pb(II). The limits of detection and quantification were 0.6 μg L− 1 and 1.84 μg L− 1, respectively. The reproducibility and repeatability calculated as the relative standard deviations were 7.4% and 7.0%, respectively. The sample throughput was 21 sample h− 1. Argentina raw propolis samples were analyzed and some of them showed high levels of lead. The obtained results with this method are in good agreement with that obtained with the ICP-AES technique. Moreover, it is a good alternative to the quality control of raw propolis. Fil: Pierini, Gastón Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Granero, Adrian Marcelo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Centurión, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Zon, María Alicia. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Fernandez, Hector. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

This article reports a flow-injection spectrophotometric determination (FIA) with a photodegradation step to determine ascorbic acid and total sugars. The flow-injection system includes a simple ultraviolet photoreactor for the on-line photodegradation. The method is based on the determination of ascorbic acid at 300. nm before the photodegradation step, followed by UV irradiation and measurement of total sugars at 268. nm. The proposed method was used to determine ascorbic acid and total sugars in commercial and natural fruit juice samples. The method was validated by using spiked samples with recoveries in the range 96.4-108.3% for ascorbic acid, and 91.0-113.2% for total sugars. © 2010 Elsevier Inc. Fil: Llamas, Natalia Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Fernández Band, Beatriz Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

In this study, a novel, simple, and efficient spectrofluorimetric method to determine directly and simultaneously five phenolic compounds (hydroquinone, resorcinol, phenol, m-cresol and p-cresol) in air samples is presented. For this purpose, variable selection by the successive projections algorithm (SPA) is used in order to obtain simple multiple linear regression (MLR) models based on a small subset of wavelengths. For comparison, partial least square (PLS) regression is also employed in full-spectrum. The concentrations of the calibration matrix ranged from 0.02 to 0.2 mg L(-1) for hydroquinone, from 0.05 to 0.6 mg L(-1) for resorcinol, and from 0.05 to 0.4 mg L(-1) for phenol, m-cresol and p-cresol; incidentally, such ranges are in accordance with the Argentinean environmental legislation. To verify the accuracy of the proposed method a recovery study on real air samples of smoking environment was carried out with satisfactory results (94-104%). The advantage of the proposed method is that it requires only spectrofluorimetric measurements of samples and chemometric modeling for simultaneous determination of five phenols. With it, air is simply sampled and no pre-treatment sample is needed (i.e., separation steps and derivatization reagents are avoided) that means a great saving of time.

A fast chromatographic methodology is presented for the analysis of three synthetic dyes in non-alcoholic beverages: amaranth (E123), sunset yellow FCF (E110) and tartrazine (E102). Seven soft drinks (purchased from a local supermarket) were homogenized, filtered and injected into the chromatographic system. Second order data were obtained by a rapid LC separation and DAD detection. A comparative study of the performance of two second order algorithms (MCR-ALS and U-PLS/RBL) applied to model the data, is presented. Interestingly, the data present time shift between different chromatograms and cannot be conveniently corrected to determine the above-mentioned dyes in beverage samples. This fact originates the lack of trilinearity that cannot be conveniently pre-processed and can hardly be modelled by using U-PLS/RBL algorithm. On the contrary, MCR-ALS has shown to be an excellent tool for modelling this kind of data allowing to reach acceptable figures of merit. Recovery values ranged between 97% and 105% when analyzing artificial and real samples were indicative of the good performance of the method. In contrast with the complete separation, which consumes 10 mL of methanol and 3 mL of 0.08 mol L-1 ammonium acetate, the proposed fast chromatography method requires only 0.46 mL of methanol and 1.54 mL of 0.08 mol L-1 ammonium acetate. Consequently, analysis time could be reduced up to 14.2% of the necessary time to perform the complete separation allowing saving both solvents and time, which are related to a reduction of both the costs per analysis and environmental impact. Fil: Culzoni, Maria Julia. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Schenone, Agustina Violeta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Llamas, Natalia Elizabeth. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Garrido, Mariano Enrique. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Di Nezio, Maria Susana. Universidad Nacional del Sur; Argentina Fil: Fernández Band, Beatriz Susana. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Goicoechea, Hector Casimiro. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

This paper proposes an analytical method to determine directly and simultaneously five phenolic compounds (4-nitrophenol, 2-nitrophenol, phenol, 2,4,6-trichlorophenol and 4-chlorophenol) in sea water (Ria de Bahía Blanca, Argentine). The advantages of this method is that only requires spectrophotometric measurements (separation steps and derivatization reagents are avoided) and chemometric modelling (PLS and MLR-SPA). The statistical comparison between PLS - a well established multivariate method - and MLR-SPA - a recently presented chemometric modelling - demonstrated better analytical performance for the later one. This fact is indicative of the potentiality of MLR-SPA for solving complex analytical problems. Fil: Di Nezio, Maria Susana. Universidad Nacional del Sur; Argentina Fil: Pistonesi, Marcelo Fabian. Universidad Nacional del Sur; Argentina Fil: Fragoso, Wallace D.. Universidade Federal Da Paraiba; Fil: Pontes, Márcio J.C.. Universidade Federal Da Paraiba; Fil: Goicoechea, Hector Casimiro. Universidad Nacional del Litoral; Argentina Fil: Araujo, Mário C.U.. Universidade Federal Da Paraiba; Fil: Fernández Band, Beatriz Susana. Universidad Nacional del Sur; Argentina

A novel home-made hybrid detection system was designed for simultaneous determination of caffeine (CAF), dipyrone (DIP) and ergotamine (ERG) in pharmaceutical preparations. Thus, ERG was determined by a fluorimetric signal and PLS-1 method for resolving DIP and CAF UV-V spectral data was used. The calibration curve for ERG was linear over the range 2.5 - 10 mg L-1. The calibration set consisted of 18 mixtures with 0.5 to 4 mg L-1 for CAF, 5 to 20 mg L-1 for DIP and 2.5 and 10 mg L-1 for ERG. Sample preparation prior to analysis was not required. A recovery study with the real samples was carried out and the obtained results were highly satisfactory. Um novo sistema híbrido para detecção simultânea de cafeína (CAF), dipirona (DIP) e de ergotamina (ERG) foi desenvolvido para teste de preparações farmaceuticas. ERG foi determinada por um sinal fluorimétrico, enquanto para CAF e DIP foi utilizado o método PLS-1 para resolução de dados espectrométricos de UV-Vis. A curva de calibração da ERG foi linear na faixa de 2.5 10 mg L-1. O conjunto de calibrações constiui-se de 18 soluções com 0.5 a 4 mg L-1de CAF, 5 a 20 mg L-1 de DIP e de 2.5 e 10 mg L-1 de ERG. Não foi necessária a prepração de amostras anterior à análise. Foram realizados estudos de recuperação com amostras reais obtendo-se resultados altamente satisfatórios Fil: Di Nezio, Maria Susana. Universidad Nacional del Sur. Departamento de Química; Argentina Fil: Pistonesi, Marcelo Fabian. Universidad Nacional del Sur. Departamento de Química; Argentina Fil: Centurión, María Eugenia. Universidad Nacional del Sur. Departamento de Química; Argentina Fil: Palomeque, Miriam Edid. Universidad Nacional del Sur. Departamento de Química; Argentina Fil: Lista, Adriana Guillermina. Universidad Nacional del Sur. Departamento de Química; Argentina Fil: Fernández Band, Beatriz Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

The determination of phenolic compounds is of great importance owing to their high toxicity. Some of them are present in tobacco smoke and it is important for their monitoring in air of closed room. A simple, rapid and sensitive method was developed for simultaneous determination of hydroquinone, resorcinol and phenol in this kind of samples. Synchronous fluorescence technique was used and the data were processed by using the partial least-squares (PLS) chemometric algorithm. The concentrations for experimental calibration matrix were varied between 0.02 and 0.2 mg L(-1) for hydroquinone, between 0.05 and 0.6 mg L(-1) for resorcinol and between 0.05 and 0.4 mg L(-1) for phenol in accordance with the national legislation. The cross-validation method was used to select the number of factors. To check the accuracy of the proposed method a recovery study on real samples was carried out.

The spectrophotometric determination of Cd(II) using a flow injection system provided with a solid-phase reactor for cadmium preconcentration and on-line reagent preparation, is described. It is based on the formation of a dithizone-Cd complex in basic medium. The calibration curve is linear between 6 and 300 μg L-1 Cd(II), with a detection limit of 5.4 μg L -1, an RSD of 3.7% (10 replicates in duplicate) and a sample frequency of 11.4 h-1. The proposed method was satisfactorily applied to the determination of Cd(II) in surface, well and drinking waters. Fil: Di Nezio, Maria Susana. Universidad Nacional del Sur. Departamento de Química; Argentina Fil: Palomeque, Miriam Edid. Universidad Nacional del Sur. Departamento de Química; Argentina Fil: Fernández Band, Beatriz Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

A new flow injection (FI) system for the determination of Pb(II) at trace level with a preconcentration step and spectrophotometric detection is proposed. It is based on preconcentration of lead ions on chitosan and dithizone-lead complex formation in aqueous medium (pH 9). The chemicals and FIA variables influencing the performance of the system were optimized and applied to the determination of lead in natural, well, and drinking water samples. It is a simple, highly sensitive, and low cost alternative methodology. The method provided a linear rage between 25 and 250 μg l-1, a detection limit of 5.0 ng ml-1 and a sample throughput of 15 h-1. The obtained results of spiked samples are in good agreement between the proposed method and ICP-AES. Fil: Di Nezio, Maria Susana. Universidad Nacional del Sur. Departamento de Química; Argentina Fil: Palomeque, Miriam Edid. Universidad Nacional del Sur. Departamento de Química; Argentina Fil: Fernández Band, Beatriz Susana. Universidad Nacional del Sur. Departamento de Química; Argentina