Distribution of trace metals in marine sediments of the Bay of Palma de Mallorca (Mallorca Island, Spain).

Metals were determined in surface bottom marine sediments of the Bay of Palma de Mallorca (Spain) by microwave-assisted acid-oxidant digestion and inductively coupled plasma-optical emission spectrometry in order to assess the level and distribution of potentially metallic pollutants. Average concentrations found were 1.2 ± 0.3 Al and 1.9 ± 0.9 Fe (in milligrams per gram), and 8 ± 2 Cr, 2 ± 1 Cu, 60 ± 10 Mn, 4 ± 1 Ni, 6 ± 4 Pb, 50 ± 7 Sn and 10 ± 3 Zn (in micrograms per gram). Enrichment factors using normalized values to Al were also calculated which indicated that sediments were Sn and Pb enriched. Sediments were fractionated by grain size: <63, 63-250, 250-500 and >500 (in micrometres), and the metals' affinity towards the different fractions was studied. The metals' affinity to the finer fraction was evidenced, excluding Sn and Mn that showed practically no affinity for fine grains. Latent variables were extracted from the data using principal components analysis. It allowed samples to be grouped in two clusters, and most of the metals (Al, Cr, Cu, Fe, Ni, Pb and Zn) showed a similar distribution pattern. Sn and Mn showed a distinct pattern.

Automated system for on-line determination of dimethylarsinic and inorganic arsenic by hydride generation-atomic fluorescence spectrometry.

A multisyringe flow-injection approach has been coupled to hydride generation-atomic fluorescence spectrometry (HG-AFS) with UV photo-oxidation for dimethylarsinic (DMA), inorganic As and total As determination, depending on the pre-treatment given to the sample (extraction or digestion). The implementation of a UV lamp allows on-line photo-oxidation of DMA and the following arsenic detection, whereas a bypass leads the flow directly to the HG-AFS system, performing inorganic arsenic determination. DMA concentration is calculated by the difference of total inorganic arsenic and measurement of the photo-oxidation step. The detection limits for DMA and inorganic arsenic were 0.09 and 0.47 µg L(-1), respectively. The repeatability values accomplished were of 2.4 and 1.8%, whereas the injection frequencies were 24 and 28 injections per hour for DMA and inorganic arsenic, respectively. This method was validated by means of a solid reference material BCR-627 (muscle of tuna) with good agreement with the certified values. Satisfactory results for DMA and inorganic arsenic determination were obtained in several water matrices. The proposed method offers several advantages, such as increasing the sampling frequency, low detection limits and decreasing reagents and sample consumption, which leads to lower waste generation.

Applicability of multisyringe chromatography coupled to on-line solid-phase extraction to the simultaneous determination of dicamba, 2,4-D, and atrazine.

Simultaneous determination of three herbicides (dicamba, 2,4-D, and atrazine) has been achieved by on-line solid-phase extraction (SPE) coupled to multisyringe chromatography (MSC) with UV detection. The preconcentration conditions were optimized; a preconcentration flow rate of 0.5 mL min(-1) and elution at 0.8 mL min(-1) were the optimum conditions. A C(18) (8 mm i.d.) membrane extraction disk conditioned with 0.3 mol L(-1) HCl in 0.5% MeOH was used. A 3-mL sample was preconcentrated, then eluted with 0.43 mL 40:60 water-MeOH. A C(18) monolithic column (25 mm × 4.6 mm) was used for chromatographic separation. Separation of the three compounds was achieved in 10 min by use of 0.01% aqueous acetic acid-MeOH (60:40) as mobile phase at a flow rate of 0.8 mL min(-1). The limits of detection (LOD) were 13, 57, and 22 µg L(-1) for dicamba, 2,4-D, and atrazine, respectively. The sampling frequency was three analyses per hour, and each analysis consumed only 7.3 mL solvent. The method was applied to spiked water samples, and recovery between 85 and 112% was obtained. Recovery was significantly better than in the conventional HPLC-UV method. These results indicated the reliability and accuracy of this flow-based method. This is the first time this family of herbicides has been simultaneously analyzed by on-line SPE-MSC using a monolithic column.

A novel procedure for phase separation in dispersive liquid-liquid microextraction based on solidification of the aqueous phase.

In this paper, an alternative for handling the organic phase after a dispersive liquid-liquid microextraction using organic solvents lighter than water is presented. It is based on solidification (at -18°C) of the aqueous phase obtained after centrifugation, and the decantation, collection and analysis of the liquid organic layer. The extraction of nicotine in toluene, and its determination in eggplant samples was conducted as a proof of concept. The study has been carried out using standards prepared in water and the formation of the dispersion was assisted by sonication. The organic extract was analysed using gas chromatography coupled to mass spectrometry. Satisfactory analytical figures of merit as: limit of detection (0.4µgL(-1), 2ngg(-1) wet sample), limit of quantification (1.2µgL(-1), 6.5ngg(-1) wet sample), within-day precision (RSD=7%), and linearity interval (up to 384µgL(-1) nicotine) were achieved. It constituted a contribution to the handling of organic extracts after microextraction processes.

Determination of polycyclic aromatic hydrocarbons using lab on valve dispersive liquid-liquid microextraction coupled to high performance chromatography.

In this work, dispersive liquid-liquid microextraction (DLLME) method was applied for high performance liquid chromatography (HPLC) determination of 15 PAHs in aqueous matrices.The extraction procedure was automated using a system of multisyringe flow injection analysis coupled to HPLC instrument with fluorescence detector. Factors affecting the extraction process, such as type and volume of extraction and dispersive solvent, extraction time and centrifugation step were investigated thoroughly and optimized utilizing factorial design. The best recovery was achieved using 100 µL of trichloroethylene as the extraction solvent and 900 µL of acetonitrile as the dispersive solvent.The results showed that extraction time has no effect on the recovery of PAHs. The enrichment factors of PAHs were in the range of 86-95 with limits of detection of 0.02-0.6 µg L(-1). The linearity was 0.2-600 µg L(-1) for different PAHs. The relative standard deviation (RSD) for intra- and inter-day of extraction of PAHs were in the range of 1.6-4.7 and 2.1-5.3, respectively, for five measurements.The developed method was used to assess the occurrence of 15 PAHs in tap water, rain waters and river surface waters samples.

Automated growth of metal-organic framework coatings on flow-through functional supports.

A fully automated method for the controlled growth of metal-organic framework coatings on flow-through functional supports is reported. The obtained hybrid flow-through supports show high performance for the automated extraction of water pollutants.

Arsenic fractionation in agricultural soil using an automated three-step sequential extraction method coupled to hydride generation-atomic fluorescence spectrometry.

A fully automated modified three-step BCR flow-through sequential extraction method was developed for the fractionation of the arsenic (As) content from agricultural soil based on a multi-syringe flow injection analysis (MSFIA) system coupled to hydride generation-atomic fluorescence spectrometry (HG-AFS). Critical parameters that affect the performance of the automated system were optimized by exploiting a multivariate approach using a Doehlert design. The validation of the flow-based modified-BCR method was carried out by comparison with the conventional BCR method. Thus, the total As content was determined in the following three fractions: fraction 1 (F1), the acid-soluble or interchangeable fraction; fraction 2 (F2), the reducible fraction; and fraction 3 (F3), the oxidizable fraction. The limits of detection (LOD) were 4.0, 3.4, and 23.6 µg L(-1) for F1, F2, and F3, respectively. A wide working concentration range was obtained for the analysis of each fraction, i.e., 0.013-0.800, 0.011-0.900 and 0.079-1.400 mg L(-1) for F1, F2, and F3, respectively. The precision of the automated MSFIA-HG-AFS system, expressed as the relative standard deviation (RSD), was evaluated for a 200 µg L(-1) As standard solution, and RSD values between 5 and 8% were achieved for the three BCR fractions. The new modified three-step BCR flow-based sequential extraction method was satisfactorily applied for arsenic fractionation in real agricultural soil samples from an arsenic-contaminated mining zone to evaluate its extractability. The frequency of analysis of the proposed method was eight times higher than that of the conventional BCR method (6 vs 48 h), and the kinetics of lixiviation were established for each fraction.

Disfunción del conducto faringotimpánico. El ETDQ-7 como herramienta para el diagnóstico clínico / Pharyngothympanic tube dysfunction. The ETDQ-7 as a tool for clinical diagnosis

RESUMEN En la actualidad se hace referencia en la bibliografía a una gran variedad de métodos para evaluar la disfunción del conducto faringotimpánico (DCFT), la gran mayoría de ellos requiere de instrumental de alta complejidad y personal altamente capacitado. Pese a lo mencionado, ninguno de dichos métodos ha sido validado como herramienta gold standard para el diagnóstico de esta patología. En este contexto, se presenta una herramienta complementaria para el diagnóstico de la DCFT, el Eustachian Tube Dysfunction Questionnaire -7 ítemes (ETDQ-7); cuestionario autoadministrado que considera 7 preguntas en base a una escala de Likert, fue creado para evaluar la sintomatología asociada a la disfunción del conducto con una puntuación que va desde lo más leve (1 punto) a lo más grave (7 puntos) de acuerdo con los síntomas percibidos, y posee un puntaje máximo de 49 puntos, correspondiente a una disfunción severa. La presente revisión tiene como objetivo buscar, organizar, clasificar y describir la información disponible en publicaciones científicas indexadas sobre el ETDQ-7 como herramienta para el diagnóstico clínico complementario de la DCFT. Se incluyeron 11 artículos científicos que hacen referencia al uso del ETDQ-7 en diferentes países. Los resultados recabados sugieren que el ETDQ-7 sería una valiosa herramienta, de alta sensibilidad, especificidad y validez clínica, que permitiría discriminar la presencia de la DCFT. No se encontró evidencia respecto a la aplicación o validación de este cuestionario en nuestro país.

ABSTRACT At present, great variety of methods are described to evaluate the dysfunction of the pharyngotympanic duct (DCFT), the vast majority of them require highly complex instruments and highly trained personnel. Despite this, none of these methods has been validated as the gold standard for the diagnosis of this pathology. In this context, a complementary tool for the diagnosis of the DCFT is presented. The Eustachian Tube Dysfunction Questionnaire-7 items (ETDQ-7), a self-administered questionnaire that includes 7 questions based on a Likert scale, was created to evaluate the symptomatology associated with the dysfunction of the duet. It is scored ranging from the mildest symptomatology (1 point) to the most severe (7 points), according to the perceived symptoms, with a maximum score of 49 points, corresponding to a severe dysfunction. The present review aims to search, organize, classify and describe the available information in scientific indexed journals about the ETDQ-7 as a tool for complementary diagnosis of the DCFT. Eleven scientific articles were included, referred to the use of ETDQ-7 in different countries, describing it as a valid tool which allows to discriminate the presence of a DCFT.

Particle size distribution of major inorganic species in atmospheric aerosols from Majorca (Spain).

Atmospheric aerosols collected by means of a cascade impaction system at the campus of the University of the Balearic Islands (Majorca, Spain) from November 1993 to February 1994 were analysed for chloride, nitrate, sulphate, ammonium, calcium, magnesium, sodium and potassium. Based on particle size distribution, the species studied were classified into three groups: (a) concentration decrease with particle size (sulphate and ammonium), (b) concentration increase with particle size (chloride, calcium, magnesium and sodium), and ( c) independent of particle size (nitrate and potassium). A principal component analysis (PCA) revealed a clear relationship between particle size and analyte origin. Also, the origin of sulphate and potassium fine and coarse particles was found to be different.

Minipol, a desk-computer program for refinement of protonation constants from differential-pulse polarographic data.

The program MINIPOL, designed to run on a desk-computer with 32 kbytes of memory, can calculate the optimum values of overall protonation constants and molar intensities of up to 8 species with composition H(XXX)L(rho), from differential-pulse polarographic data.

Automatic kinetic determination of Hg(II) by anodic stripping potentiometry with constant current oxidation.

A new kinetic method for the determination of Hg(II) is proposed. It is based on the kinetic evolution of the anodic stripping potentiometric curves yielded by a gold electrode previously coated with mercury upon passage of constant electrical currents. The method features a linear determination range between 40 and 800 ppb of Hg(II) and a relative standard deviation of 5% (n = 9) for a mercury concentration of 200 ppb. The experiments were conducted on a customized automatic set-up, and instrumentation, data acquisition and processing were all governed by means of a QBASIC program (PSAKINEL) written by the authors.

Potentiometric stripping analysis automation.

A semi-automatic system for potentiometric stripping analysis (PSA) based on the use of a potentiostat, a pH-meter with RS232C interface, and a personal computer is described. The appropriate software developed allows automatic control of the pre-electrolysis time, data acquisition and manual or automatic data treatment. Several elements can be determined at ng/ml level.

A simple thermometric technique for reaction-rate determination of inorganic species, based on the iodide-catalysed cerium(IV)-arsenic(III) reaction.

A very simple reaction-rate thermometric technique is used for determination of iodide (5-20 ng ml ), based on its catalytic action on the cerium(IV)-arsenic(III) reaction, and for determination of mercury(II) (1.5-10 ng ml ) and silver(I) (2-10 ng ml ), based on their inhibitory effect on this reaction. The reaction is followed by measuring the rate of temperature increase. The method suffers from very few interferences and is applied to determination of iodide in biological and inorganic samples, and Hg(II) and Ag(I) in pharmaceutical products.

New computational approach for the simultaneous photometric determination of catalysts and activators.

A new method for the simultaneous kinetic determination of catalysts and activators was developed on the basis of a mathematical model. The parameters and variables are optimized from experimental data obtained by application of a multiple standard-addition method and use of the Gauss-Newton and Simplex method, both of which provide identical results. The proposed method was applied to the simultaneous photometric determination of Mn(II) and Pb(II) on the basis of their catalytic and activating effects, respectively, on the oxidation of Tiron by hydrogen peroxide. Data were both acquired and processed with the aid of software developed by the authors. The linear determination range achieved was 1.00-5.00 ng/ml Mn(II) and 200-800 ng/ml Pb(II). Experimental readings were made at 450 nm with a fibre optics detector. The most serious interference with the method was posed by Cr(III).

Effect of variables influencing S 1/2 in sequential injection analysis. Extrapolability of S 1/2 based results between SIA designs.

The influence of variables including ionic strength, propulsion rate and instrumental design parameters on dispersion in a sequential injection analysis system was studied via S(1/2) and several other parameters related to the dispersion profile. The influence of such parameters on a real system was evaluated in the reaction of Fe(II) with o-phenanthroline by optimizing various instrumental designs using the simplex method and comparing the results.

Multidata treatment applied to the simultaneous resolution of catechol-resorcinol mixtures by kinetic enzymatic processes.

This paper reports a multicomponent least-squares regression method based on the use of multiple standards for the simultaneous resolution of substrates involved in kinetic enzymatic processes. The proposed method was applied to the determination of catechol-resorcinol mixtures by oxidation with hydrogen peroxide in the presence of the enzyme peroxidase (EC 1. 11.1.7) in a stopped-flow reversed flow injection system. The mathematical algorithm used is superior to other alternatives as it is not affected by side reactions between the oxidation products. The proposed method allows the simultaneous resolution of 50-150,muM catechol and 30-180,muM resorcinol over the wavelength range 340-500 nm. The concentration ranges can be modified by varying the injected amount of enzyme. The mathematical treatment is applied to the spectra of several standards and those of the samples, which are recorded 6 sec after the flow is stopped. This redounds to a high sampling frequency (up to 60/hr).

Valgran, a program for potentiometric titrations with a versatile automatic modular system.

A very flexible modular system for use with a portable IBM PC for potentiometric titrations is described. The appropriate software has been developed in order to obtain automatic end-points, and conventional, first-derivative, second-derivative and Gran curves, as well as a listing of the potentiometric points expressed in different ways. All these alternatives are selectable on menu presentations. The potentiometric system has been applied both the research and routine problems.

Preconcentration and atomic absorption determination of iron by sequential injection analysis.

A sequential injection analysis (SIA) assembly for the atomic absorption determination of Fe(III) in natural waters is proposed. Iron is preconcentrated on a microcolumn packed with a chelating resin (Chelex 100) that is inserted in the manifold. The sample is passed through the column and the iron retained by the resin is subsequently eluted with 2 M HNO(3). The proposed SIA system affords automatic preconcentration, elution, detection of Fe(III), data acquisition and treatment. When 9 ml of iron solution containing 0.4 or 1 mg l(-1) was passed through the resin, the retention efficiency was 93.1 +/- 0.6 and 7.4 +/- 3.0% respectively, and when 27 ml of iron solution of 0.2 mg l(-1) was preconcentrated, the retention was 8.4 +/- 2.9%. The detection limits thus achieved is 12 mug l(-1) when 9 ml of sample are preconcentrated and 6 mug l(-1) for 27 ml.

Flow techniques in water analysis.

In the present work the main flow techniques for the analysis and monitoring of several parameters of interest in the quality control of different types of waters are reviewed. Firstly, a review involving the advantages and disadvantages of flow techniques, from those currently out-dated, such as segmented flow analysis (SFA), to the most modern techniques, such as flow injection analysis (FIA), sequential injection analysis (SIA) and multi-commutation techniques (MCFA), is carried out. On the other hand, a new technique, the multi-syringe flow analysis (MSFA) is hereby described for the first time as both a fast and robust alternative. Its possibilities, limitations and potential advantages when using this technique either on its own or coupled to SIA, which carries out a previous sample handling, are outlined.