Simultaneous determination of traces of PT, PD, OS, IR, RH, AG and AU by using magnetic nanoparticles solid phase extraction coupled with ICP OES

The direct analysis of these target analytes is very limited being essential sample pre-treatment techniques and the use of very sensitive instrumental techniques to carry out determinations. The inductively coupled plasma optical emission spectrometry shows a poor sensitivity because the concentration of some elements in environmental samples is below the detection limit of ICP OES. To solve this problem, preconcentration separation procedures have been proposed, minimizing the spectral and matrix interferences. Thus, enrichment is a very important issue for achievement of low detection limits [1-4]. In this study, a chelating resin 1,5 bis (di 2 pyridil) methylene thiocarbonohydrazide bonded to iron oxide magnetic nanoparticles (DPTH-MNPs) were synthesized. These magnetic nanoparticles were employed as a solid phase extraction (SPE) adsorbent for the separation and concentration of trace amounts of 7 elements (Au, Ag, Pd, Pt, Ir, Rh and Os) from environmental water samples. The main aim of this work was to develop a precise and accurate method for the simultaneous determination of the maximum possible number of elements by using this new absorbent and a multimode sample introduction system (MSIS). The MSIS acts as a system for the generation, separation and introduction of chemical vapours (CVG) and also as an introduction system for sample aerosols, in a simultaneous form, into an inductively coupled plasma-optical emission spectrometer. The on-line SPE-CVG-ICP-OES system developed was applied in the determination of the aforementioned metals in natural water samples (sea water, estuarine, lake and river water), with the least demanding and simple sample preparation procedure. The developed method was validated by analysing natural water certified reference materials (TMDA 54.4 fortified lake waters and SRM 1643e, trace elements in water; and National Institute of Standards and Technology (NIST), NIST-2557 autocatalyst). Sea water, tap water and well water samples collected from Malaga (Spain) were also analysed. The procedure has been demonstrated to be fast, easy, automatic, selective and economical, and the sensitivity was good. The main advantage of DPTH-MNPs is its very good stability and resistance because chemisorption of chelating molecules on the surface of solid supports provides immobility, mechanical stability and insolubility. The precision (RSD), accuracy (by standard addition or recovery) and limit of detection (LOD) were used to evaluate the characteristics of the procedure. Furthermore, the proposed method was applied in the simultaneous determination of the 7 elements mentioned above with a sample throughput of about 13 h-1, thereby, reducing the time of analysis and the volume of reagents and sample required. References [1] M. Tuzen, M. Soylak, D. Citak, H.S. Ferreira, M.G.A. Korn, M.A. Bezerra, A pre-concentration system for determination of copper and nickel in water and food samples employing flame atomic absorption spectrometry, Journal of Haz-ardous Materials 162 (2009) 1041–1045. [2] Y. Cui, X. Chang, Y. Zhai, X. Zhu, H. Zheng, N. Lian, ICP-AES determination of trace elements after preconcentrated with p-dimethylaminobenzaldehyde-modified nanometer SiO2 from sample solution, Microchem. J. 83 (2006) 35–41. [3] P. Liang, B. Hu, Z. Jiang, Y. Qin, T. Peng, Nanometer-sized titanium dioxide micro-column on-line preconcentration of La, Y, Yb, Eu, Dy and their determination by inductively coupled plasma atomic emission spectrometry, J. Anal. Atom. Spectrom. 16 (2001) 863–866. [4] B. Feist, B. Mikula, K. Pytlakowska, B. Puzio, F. Buhl, Determination of heavy metals by ICP-OES and F-AAS after preconcentration with 2,2-bipyridyl and erythrosine, J. Hazard. Mater. 152 (2008) 1122–1129.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Seroprevalencia del VIH en pacientes con tuberculosis Nicaragua, mayo 1998, febrero 2000

Investigación realizada en 51 centros de salud de todos los silais en el país. Es estudio de tipi descriptivo, de corte transversal, llevado a cabo mediante una encuesta serológica anónima no ligada cuyo objetivo era estimar la seroprevalencia del vih entre los pacientes con tuberculosis de nuevo ingreso. Se describen las características personales y el tipo de tuberculosis de los pacientes asociados a los casos seropositivo

Sequential determination of traces of As, Sb and hg by on-line magnetic solid phase extraction coupled with Hr-Cs-Cvg-Gfaas

A green and rapid method was developed for the simultaneous separation/preconcentration and sequential monitoring pf arsenic, antimony and mercury by flow injection magnetic solid phase extraction coupled with on-line chemical vapor generation and determination by high resolution continuum source graphite furnace atomic absorption spectrometry. The system is based on chelating/cationic retention of the analytes onto a magnet based reactor designed to contain functionalized magnetic nanoparticles (MNPs). The MNP score allows overcoming the back-pressure problems that usually happen in SPME methods with NPs thanks to the possibility of inmobilizing the MNPs by applying an external magnetic field. Several chemical and flow variables were considered as factors in the optimization process using central composite designs. With the optimized procedure the detection limits obtained were 0.2, 0.003 and 0.4 µg/L for As, Sb and Hg respectively. For the quality control of the analytical performance and the validation of the developed method the analysis of two certified samples TM 24.3 and TMDA 54.4 Fortified Lake Waters was addressed. The results showed good agreement with the certified values.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Cold vapour generation electrothermal atomic absorption spectrometry and solid phase extraction based on a new nanosorbent for sensitive HG determination in environmental samples (sea water and river water)

Reunión bianual del Grupo Regional Andaluz de la Sociedad Española de Química AnalíticaMercury is not an essential element for plant or animal life and it is a potential environmental toxic because of its tendency to form covalent bonds with organic molecules and the high stability of the Hg-C bond. Reports estimate a total mercury concentration in natural waters ranging from 0.2 to 100 ng L-1. Due to this fact, highly sensitive methods are required for direct determination of such extremely low levels. In this work, a rapid and simple method was developed for separation and preconcentration of mercury by flow injection solid phase extraction coupled with on-line chemical vapour generation electrothermal atomic absorption spectrometry. The system is based on chelating retention of the analyte onto the mini column filled with a mesoporous silica functionalized with 1,5 bis (di-2-pyridyl) methylene thiocarbohydrazide. The main aim of this work was to develop a precise and accurate method for the determination of the Hg. Under the optima conditions and 120 s preconcentration time, the detection limit obtained was 0.009 μg L-1, with RSDs 3.7 % for 0.2 μg L-1, 4.8 % for 1 μg L-1 and enrichment factor 4, Furthermore, the method proposed has permitted the determination of Hg with a reduction in the analysis time, the sample throughput was about 18 h-1, low consumption of reagents and sample volume. The method was applied to the determination of Hg in sea water and river water. For the quality control of the analytical performance and the validation of the newly developed method, the analysis of two certified samples, TMDA 54.4 Fortified Lake, and LGC6187 River sediment was addressed. The results showed good agreement with the certified values.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Determination of Pb using F3eO4 GO join to DPTH for ferrofluid based dispersive solid phase extraction

In this work has been described a green and rapid method the synthesis of Fe3O4@GO nanospheres via chemical covalent bonding method. The Fe3O4@GO DPTH was applied to ferrofluid based dispersive solid phase extraction of lead as a model analyte using an ionic liquid carrier. The ferro fluid allows the rapid extraction of lead ions using a low amount of sorbent material. Besides, the magnetic separation greatly improved the separation rate. The presented method is highly time saving due to the high dispersion of the sorbent in the aqueous phase and also there is no need to shake the sample solution. The other benefits of the proposed methods are simplicity of operation, low cost, high sorption capacity, high recovery and high preconcentration. In order to optimize the method the following parameters were studied: sample solution pH, concentration of DPTH, extraction time, amount of sorbent, desorption conditions, influence of ionic strength, and tolerance of potentially interfering ions. The sample or standard solution containing Pb(II), DPTH (0.05% ethanol w/v), NaCl (0.5 %, w/v) and buffer (pH = 5.6) was poured into high volume. Then 240 µL of ferrofluid was injected rapidly into the sample solution through a syringe. Thereupon, a dark cloudy suspension was formed, ferrofluid was dispersed thoroughly in solution and the complex of Pb-DPTH was extracted in a few seconds. Subsequently, a strong magnet was placed at the bottom of the tube to let the extractant settle. After about 3 min, the solution became clear and the supernatant was discarded simply by decanting it. Afterwards, the magnet was removed and 1 mL of nitric acid (2.0 mol L−1) was introduced to the vial to desorb the Pb by sonication. Finally, the sorbent was separated by positioning the magnet to the outside of the tube and the concentration of Pb in acidic aqueous phase was determined by ETAAS.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Las actas capitulares como fuente para la historia urbana.

Sin resume

Magnetic dispersive solid phase microextraction coupled with on-line chemical vapor generation method to extraction/preconcentration of mercury from environmental samples and determination by graphite furnace atomic absorption spectrometry.

Mercury (Hg) is classified as priority hazardous substances. Concentrations found in the aquatic environment are at trace levels as result of natural processes, such as erosion and volcanism, and anthropogenic discharges related mainly to industrial and mining activities. Mercury is one of the most potent neurotoxins known, showing a high number of adverse health effects in animals and humans. For this reason, a simple and rapid method for the determination and preconcentration of mercury in environmental waters is proposed. This work is based on magnetic dispersive solid phase microextraction (MDSPME) coupled with on-line chemical vapour generation (CVG). Graphite furnace atomic absorption spectrometry (GFAAS) was employed for the quantification of Hg. In the preconcentration step, a shell structured Fe3O4@graphene oxide was suspended in the ionic liquid carrier (1-n-butyl-3-metilimidazolium tetrafluoroborate [BMIM][BF4]), obtaining a stable colloidal suspension called ferrofluid. This sorbent possesses as large contact surface area and a high density of polar groups on its surface. The nanoparticles, when finely dispersed in the sample solution, result in almost complete extraction of Hg within a few seconds. All experimental and instrumental variables were optimized and the method was adequately validated by the analysis of certified reference materials of environmental waters. Acknowledgements The authors would like to thank Plan Propio “Proyecto Puente” de la Universidad de Málaga for financial support of this work.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Solid sampling determination of ZnO nanoparticles in eyeshadows by graphite furnace atomic absorption spectrometry

The application of nanoparticles (NPs) in science and technology is a fast growing field. Therefore, reliable and straightforward analytical methods are required for their fast determination in different types of samples. In this work, a method that enables the determination of the average size of ZnO NPs, besides their concentration, discriminating them from ionic zinc, has been optimized. The method is based on solid sampling high-resolution continuum source electrothermal atomic absorption spectrometry (SS-HR-CS-GFAAS), and has been applied to determination and characterization of ZnO NPs in cosmetic samples. Recently, graphite furnace atomic absorption spectrometry has been introduced as a new tool to determine the size of nanoparticles by evaluation of the following parameters: atomization delay (tad) and atomization rate (kat). In this work both parameters (besides peak area) have been obtained from absorbance signals for a line of Zn with low sensitivity. Two multiple response surface designs have been used in order to optimize the adequate furnace program to achieve our aims. All the optimization experiments were performed using baby´s skin irritation protective cream. The optimized furnace program is shown in Table 1. Table 1. Optimized furnace program The size calibrations were performed against solid (powered) ZnO standards, from 50-nm to 500-nm sized nanoparticles. The correlation coefficients (R value) of the linear calibration were not worse than 0.9982. The optimized method was tested in other types of cosmetic samples such as eyeshadow samples with good results. The determination of the MNPs’ size was validated by transmission electron microscopy (TEM) and the Zn concentration in the solid samples was validated by atomic fluorescence spectroscopy (AFS). Acknowledgements (optional) [Garamond font, 10 points] The authors would like to thank Plan propio “Proyecto Puente” de la Universidad de Málaga for financial support of this work.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Consumo de productos de tabaco y factores asociados en mujeres en Antioquia, Colombia

Introducción: el uso del tabaco en mujeres está aumentando significativamente a pesar de los alarmantes peligros para la salud. Objetivo: determinar la prevalencia y factores asociados al consumo de tabaco en mujeres deldepartamento de Antioquia, Colombia. Materiales y métodos: estudio descriptivo transversal, con una muestrarepresentativa de mujeres mayores de 18 años en las nueve subregiones del departamento, se utilizó un muestreoprobabilístico multietápico, estratificado por región. Resultados: de 4377 mujeres, 10,8% eran fumadoras, 13,1%exfumadoras, y 75,9% nunca habían fumado. Variables relacionadas con mayor reporte de tabaquismo: tener másde 45 años (OR=3,2, IC 2,6-3,9); no tener educación o primaria incompleta (OR=2,2, IC 1,5-3,1), secundariaincompleta (OR=1,5, IC 1,1-2,2), consumir licor (OR=2,3, IC 1,9-2,7), no consumir verduras (OR=1,4, IC 1,0-2,0), no consumir frutas (OR=1,6, IC 1,2-2,1). Variables relacionadas con menor reporte de tabaquismo: estarcasada (OR=0,6, IC 0,5-0,8), y vivir en algunas de las subregiones. Conclusiones: se evidencia la importancia deprogramas enfocados a prevenir el consumo de productos nuevos como el cigarrillo electrónico, especialmente enpoblación joven.Introducción: el uso del tabaco en mujeres está aumentando significativamente a pesar de los alarmantes peligros para la salud. Objetivo: determinar la prevalencia y factores asociados al consumo de tabaco en mujeres deldepartamento de Antioquia, Colombia. Materiales y métodos: estudio descriptivo transversal, con una muestrarepresentativa de mujeres mayores de 18 años en las nueve subregiones del departamento, se utilizó un muestreoprobabilístico multietápico, estratificado por región. Resultados: de 4377 mujeres, 10,8% eran fumadoras, 13,1%exfumadoras, y 75,9% nunca habían fumado. Variables relacionadas con mayor reporte de tabaquismo: tener másde 45 años (OR=3,2, IC 2,6-3,9); no tener educación o primaria incompleta (OR=2,2, IC 1,5-3,1), secundariaincompleta (OR=1,5, IC 1,1-2,2), consumir licor (OR=2,3, IC 1,9-2,7), no consumir verduras (OR=1,4, IC 1,0-2,0), no consumir frutas (OR=1,6, IC 1,2-2,1). Variables relacionadas con menor reporte de tabaquismo: estarcasada (OR=0,6, IC 0,5-0,8), y vivir en algunas de las subregiones. Conclusiones: se evidencia la importancia deprogramas enfocados a prevenir el consumo de productos nuevos como el cigarrillo electrónico, especialmente enpoblación joven.Introduction: Tobacco use among women is increasing significantly despite alarming health hazards. Objective:To determine the prevalence and factors associated with tobacco consumption in women from the department ofAntioquia, Colombia. Material and methods: Cross-sectional descriptive study, with a representative sample of women over 18 years of age in the nine subregions of the department, using multistage probabilistic sampling,stratified by region. Results: Of the 4,377 women, 10.8% were smokers, 13.1% were ex-smokers, and 75.9% werewomen who had never smoked. Variables related to the highest reported smokers: having more than 45 years of age (OR=3.2, CI 2.6-3.9); not having an education or an incomplete primary education (OR=2.2, IC 1.5-3.1), incomplete secondary education (OR=1.5, CI 1.1-2.2), consuming liquor (OR=2.3, CI 1.9-2.7), not consuming vegetables (OR=1.4, IC 1.0-2.0), not consuming fruit (OR=1,6, CI 1,2-2,1). Variables related to less reported smoking: being married (OR=0.6, CI 0.5-0.8) and living in some of the subregions. Conclusions: The importance of programs focused on preventing the consumption of new products such as e-cigarettes is evident, especially in young people

Rapid magnetic microextraction to preconcentrate and determinate cadmium from environmental samples

A novel and greener ultrasonically assisted/modified cloud point extraction procedure for the preconcentration and extraction of trace cadmium from environmental samples was developed. The sorbent material was fabricated by scattering of magnetic iron nanoparticles (MNPs) over graphene oxide (GO) to obtain magnetic graphene oxide (MGO). The material was suspended in the ionic liquid 1-n-butyl-3-metilimidazolium tetrafluoroborate [BMIM][BF4]. The obtained stable colloidal suspension is named ferrofluid. GO presents excellent adsorbent properties for organic species due to the presence of the electronic π system. For this reason, the organic ligand [1,5-bis-(2-dipyridyl) methylene] thiocarbonohydrazide (DPTH) was used in order to form an organic complex of Cd. Once the DPTH ligand has been added to sample, the ferrofluid was injected and finely dispersed in the sample solution in order to extract the formed chelate as shown in Fig. 1. The complete adsorption of the quelate took place within few seconds, after that the solid was separated from the solution with the aid of a strong magnet. Cadmium ions were desorbed from the material with 1 mL of 5% acid nitric solution and quantified by electrothermal atomic absorption spectrometry (ETAAS). The main parameters affecting the extraction and the furnace program were optimized using one-at-time method. The analytical performance under optimum conditions are the following: LOD: 0.005 µg/L, LOQ: 0.017 µg/L. Linear calibration: 0-0.25 µg/L and EF: 200. The reliability of the developed procedure was tested by relative standard deviation (% RSD), which was found to be < 5% (1.3%). The performance of the proposed procedure was checked by applying to certified reference material and spiking standard in real samplesUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech