Coupled Extraction/Re-Extraction Method for the Chemical Speciation of Nickel in NaturalWaters

Chemical fractionation and speciation of metals species in natural waters and its relation with bioavailability have received increased attention in recent years. A simple liquid membranes method, based on coupled liquid extraction and re-extraction processes, is proposed to separate and quantify the species of nickel present in water samples. A simplex optimization of chemical variables, such as carrier concentration in the organic solution and nitric acid concentration in the receiving solution, was performed and, under optimized conditions, the extraction system was applied to determine nickel species in water samples at natural level concentrations. A linear relationship was established between extraction e cacy and the concentration of dissolved organic carbon in the samples, allowing the separation and determination of labile and non-labile nickel fractions, since the latter was not transported through the organic solution acting as liquid membrane. When the total and labile concentrations of metals were analyzed in real samples with di erent salinities, no significant di erences were found between the results obtained and those from well-established methods. An average relative error of 1.50 and 2.37 was obtained for total Ni concentration and labile fraction, respectively. Finally, a comparison with the theoretical speciation data calculated with the softwareWinHumic V was successfully performed. Thus, the proposed method allows the simultaneous determination of labile and non-labile nickel fractions, presented as a simple alternative to nickel fractionation in natural waters

Se busca Geobibliotecario: los datos geográficos entran en la biblioteca

The increased proliferation and accessibility of geographic data are changing the landscape of services based on geographic information. From the analysis of recent job offers posted in American university libraries, we discuss what could be the role of the information professional in this new context, with respect to the management and dissemination of geographic data collections, looking for synergies for mutual benefit between academic libraries and their information professionals and the geographic data community that uses geographic information systems (GIS). In fact, this activity would be one more among the data curation or data sets preservation tasks needed currently in many disciplines.La mayor proliferación y accesibilidad de los datos geográficos están cambiando el panorama de servicios basados en información geográfica. A partir del análisis de recientes ofertas de trabajo en bibliotecas universitarias americanas se analiza cuál podría ser el rol del profesional de la información en este nuevo contexto, en cuanto a la gestión y difusión de las colecciones de datos geográficos, identificando sinergias para beneficio mutuo entre las bibliotecas universitarias con sus profesionales de la información y la comunidad que usa datos geográficos y sistemas de información geográfica (SIG). De hecho esta actividad sería una más, un caso particular, de las de curación de datos que se reclama para muchas disciplinas

Key factors in electromembrane microextraction systems for metals analysis in natural waters

This is an original manuscript of an article published by Taylor & Francis in International Journal of Environmental Analytical Chemistry o 2018, available at: https://doi.org/10.1080/03067319.2018.1533006].Application of an electric potential to hollow fibre liquid phase microextraction (HF-LPME) systems previously optimised for metals preconcentration from natural waters could improve their analytical performance increasing enrichment factors and reducing operation times. Nevertheless, the effectiveness of the direct application of an electric potential to these systems may be limited due to the effects produced by other operational parameters. In this work, the effect of a variable electric potential on the enrichment factors of four HF-LPME systems used for the analysis of trace metals in natural waters (Cd, Ni, Ag and Cu) has been studied. In addition, the effect of organic phase composition, distance between electrodes and electrodes diameter has been also studied. From the results obtained, composition of organic phase can be considered as the key factor in electromembrane (EME) systems, since its polarity determine the operational range of the applied electric potential and consequently the enrichment factor that could be achieved. EMEs have demonstrated to be a real alternative to preconcentrate Cd, Ag and Cu from natural water samples in very short times (30 min). In fact, enrichment factors increased up to one order of magnitude if compared with HF-LPME methodology without application of an electrical potential

Resultados funcionales postquirúrgico evaluados con la escala Quick Dash en pacientes sometidos a cirugía de desinserción del ligamento transverso del carpo en el Hospital Militar Escuela Dr. Alejandro Dávila Bolaños en el periodo comprendido de Enero 2016 – Diciembre 2016

El presente estudio descriptivo-transversal retrospectivo realizado en 42 pacientes con diagnóstico de síndrome del túnel del carpo moderado a severo durante enero a diciembre del 2016 en el Hospital Militar Escuela Dr Alejandro Davila Bolanos de la ciudad de Managua, Nicaragua, para conocer los resultados funcionales postquirúrgico evaluados con la escala Quick Dash en pacientes sometidos a cirugía de desinserción del ligamento transverso del carpo. Se intervinieron quirúrgicamente 42 pacientes, en los cuales se utilizó la técnica de cirugía abierta para la sección del ligamento Anular mediante la desinserción de la fascia transversa del carpo, a los cuales se les dio seguimiento por 12 meses, para después evaluar la efectividad del resultado funcional de la técnica quirúrgica, por medio de la escal Quick Dash. El 100 % de los pacientes presentaron un resultado funcional satisfactorio en la intervención quirúrgica de cirugía abierta. El sexo más afectado fue el femenino con 78.3 % de los pacientes. La edad con mayor frecuencia de afección fue el comprendido intervalo de 40.5 años, con mayor incidencia de los maestros 40.5% con resultados de electromiografía moderados en un 57.1% mano derecha dominante 85.7%, con un tiempo quirúrgico de 16 minutos, con resultados de discacidad leve en el 100% casos postquirurgicos Las complicaciones encontradas fueron deshicencia del sitio quirurgico Se concluyó que hay un resultado satisfactorio catalogado como excelente hasta en un 91%, y que el sexo femenino con una edad entre 40.5 años y que trabajen en ocupaciones que exigen movimientos repetitivos de flexión y extensión de la muñeca, tiene una incidencia aumentada de presentar el síndrome del túnel del carpo. La edad promedio de la población estudiada presento una media de 40.5 años

A Green Method for the Determination of Cadmium in Natural Waters Based on Multi-Fibre Supported Liquid Membranes

Supported liquid membranes have been used to implement a hollow fibre liquid-phase microextraction (HF-LPME) method for the preconcentration of Cd(II) in natural waters as a sample preparation step for its determination by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS-GFAAS). This system was designed to use four hollow fibres simultaneously with the same sample, thus improving the simplicity, speed and reproducibility of the results. The organic liquid membrane bis-(2,4,4-trimethylpentyl) phosphinic acid (Cyanex® 272) dissolved in dihexylether (DHE) was immobilised into the pores of the walls of polypropylene hollow fibres. After extraction, the cadmium-enriched acidic phases were recovered and analysed by triplicate. To optimise the extraction process, the effect of both physical and chemical variables was studied, and optimum results with an enrichment factor (EF) of 292 were obtained for a fibre length of 6 cm, 1.06 M Cyanex 272, 0.04 M HNO3, stirring rate of 600 rpm and an extraction time of 4.26 h. For practical applications, extraction time was reduced to 2 h, keeping the EF as high as 130. Under these conditions, a detection limit of 0.13 ng L-1 Cd(II) was obtained, with a reproducibility of 3.3 % and a linear range up to 3 ug L-1 being achieved. The proposed method was successfully applied to the determination of cadmium in mineral, tap and seawater samples

Advances in ionic liquids and deep eutectic solvents-based liquid phase microextraction of metals for sample preparation in Environmental Analytical Chemistry

Liquid phase micro-extraction (LPME) of metals has showed its potential for sample preparation in environmental analysis. In particular, the incorporation of ionic liquids to LPME (IL-LPME) has gotten increasing interest due to their unique properties as organic salts liquid at room temperature. In the last years, IL-LPME of metals has evolved to more efficient and selective extraction methods thanks to the development of task specific ionic liquids, and deep eutectic solvents. ILs have been implemented in the main LPME modalities: SDME, DLLME and HFLPME, resulting in new versions of these techniques. In this review we have analyzed and discussed the latest developments done in IL-LPME of metals, their advantages and limitations, as well as the potential fields of future development. © 2021 The Author(s). Published by Elsevier B.V.This work has been supported by Spanish Ministry of Economy and Competitiveness through the research project PGC2018- 101894-B-I00. BHS also thanks the Spanish Ministry of Education, Culture and Sports for the pre-doctoral grant FPU15/03924 and the University of Cadiz for the post-doctoral grant 2019-011/PU/ AY.PUENTE/CD

Solvent bar micro-extraction with graphite atomic absorption spectrometry for the determination of silver in ocean water

Main drawbacks for silver determination in seawater are the effects of samples matrix and that Ag appears in the sub ng L−1. Available methods for sample preparation in Ag analysis are based on solid and liquid extraction using tedious process that increase the cost of analysis and the risk of sample contamination, producing important waste amounts. Solvent bar micro-extraction (SBME) allows the pre-concentration of Ag in a micro-volume of the ionic liquid Aliquat 336® in kerosene solution. For this reason, it is considered as a green alternative to standard methods. The method has been optimized using synthetic seawater samples, offering the highest response for samples at pH=2, using 5% Aliquat 336® dissolved in kerosene containing 5% dodecan-1-ol as acceptor solution and after 1 h stirring at 800 rpm. The method exhibited linearity up to 50 ng L−1, with a limit of detection of 0.09 ng L−1, covering the concentration range of interest for environmental studies. Finally, it was applied for determination of Ag in real seawater samples, and the results were compared with the reference method of liquid-liquid extraction with 1-pyrrolidine-dithiocarbamate and diethylammonium-diethyldithiocarbamate, showing the applicability of ionic liquid based SBME using Aliquat 336® for the simple monitoring of silver ultra-traces in seawater analysis

Ionic liquid solvent bar micro-extraction of CdCln(n-2)- species for ultra-trace Cd determination in seawater

Water analysis of trace metals has been benefited by recent studies on sample preparation by liquid micro-extraction. However, there are still limitations for its application to seawater, such as the need of additives to preserve the sample or the availability of chemical extractants for the selective extraction from highly saline samples. In this work, a three phase solvent bar micro-extraction (3SBME) system containing the ionic liquid trioctylmethylammonium chloride (Aliquat® 336) has been used for isolation and pre-concentration of Cd from seawater samples, due to its ability for ionic exchange of CdCln(n−2)-. The system was optimized to work at the natural pH of seawater, and conditions for application to real samples were 0.18 M Aliquat® 336 dissolved in kerosene with 0.25 M dodecan-1-ol as organic solution, 1.5 M HNO3 as acceptor solution, 60 min extraction time, and 800 rpm stirring speed in the sample. Loss of organic solution into the sample during extraction was evaluated and revealed its dependence on stirring rate and extraction time. Under optimum conditions samples containing Cd 0.09–0.90 nM were pre-concentrated 65 times. GF-AAS was used for metal quantification with a limit of detection of 0.04 nM. Accuracy was successfully evaluated measuring Cd in a seawater certified reference material BCR-403

Three phase solvent bar micro-extraction as an approach to silver ultra-traces speciation in estuarine water samples

Silver ion inputs into the environment due to human activities have been increased in the last years because it has been used as a bactericide with application in medical, homecare and self-care products. In addition, it is toxic at low concentration for aquatic organisms. In estuarine waters, salinity and dissolved organic matter (DOM) regulate Ag+ concentration by the formation of complexes as AgCln(n-1)− and Ag-DOM. Difficulties of Ag+ analysis in estuaries are associated to its low concentration level and interferences of sample matrix. Liquid and solid phase extraction methods have been used for speciation of silver in waters; however, miniaturized methods that offer a better environmental profile are desirable. Hollow fiber liquid phase micro-extraction (HFLPME) allows obtaining higher pre-concentration factors with a reduction of waste generation. Notwithstanding, some operational improvements are needed to permit their use as a routine method that can be afforded using a configuration of three-phase solvent bar micro-extraction (3PSBME). In this work, tri-isobutylphosphine sulphide (TIBPS) has been used as an extractant for Ag+ pre-concentration in estuarine waters by 3PSBME. Under optimized conditions, Ag+ has been pre-concentrated 60 times and the method presents a limit of detection of 1.53 ng L−1. To evaluate which Ag species is transported by TIBPS, Cl− and DOM have been added to synthetic samples. As a result, a decrease in Ag pre-concentration efficiency after additions has been observed and quantified. Results showed that Ag+ is selectively transported by TIBPS from estuarine water samples after comparison of the results with those obtained by the reference method of liquid extraction with APDC/DDDC

Selective ionic liquid solvent bar micro-extraction for estimation of ultra-trace silver fractions in marine waters

Ag can be found in the ocean at the ultra-trace level, mainly as AgCln(n−1)− and complexed by dissolved organic matter (Ag-DOM). However, methods for studying Ag speciation in marine waters are limited by the lack of extractants capable to separate organic and inorganic silver species in natural conditions of seawater samples. In this work, a two-phase solvent bar micro-extraction method using the ionic liquid trihexyltetradecylphosphonium chloride (Cyphos® 101) was applied for selective micro-extraction of AgCln(n−1)− from organic silver in marine waters, working at seawater pH,. The application to real samples was performed under the following conditions: 2.5% Cyphos® 101 in kerosene solution with 10% dodecan-1-ol inside the fiber, and 30 min of sample extraction at a stirring rate of 800 rpm. The proposed SBME was successfully used for estimation of Ag fractions in waters from the Bay of Cádiz (South-west Spain) showing its applicability for a simple, fast and environmentally friendly speciation of silver in marine water samples. The method presented a linear response up to 500 ng L−1 and a detection limit of 0.4 ng L−1, using GF-AAS for instrumental determination