Direct analysis of Antarctic krill by slurry sampling: determination of copper, iron, manganese and zinc by flame atomic absorption spectrometry

Slurry sampling in combination with flame atomic absorption spectrometry was employed for the direct determination of four essential trace elements, namely Cu, Fe, Mn and Zn in Antarctic krill. The effect of instrumental operating conditions and slurry sampling preparation on the analytical signal was investigated. For the determination of Cu, Fe and Zn, samples were suspended in a solution containing 2 mol L-1 HNO3. In the case of Mn, 4 mol L-1 HNO3 was necessary for the preparation of the slurry. The precision between sample replicates was better than 5%. The method was applied to the direct determination of Cu, Fe, Mn and Zn in Antarctic krill samples using aqueous reference solutions to prepare the calibration curves. The results obtained were in good agreement with those achieved by FAAS and ICP-AES after microwave-assisted wet digestion of the krill samples. The detection limits were 4.5, 1.0, 4.9 and 8.4 mug L-1 for Cu, Zn, Mn and Fe, respectively.A técnica de amostragem de suspensão aliada à espectrometria de absorção atômica com chama foi empregada para a determinação direta de Cu, Fe, Mn e Zn em matrizes de Krill antártico. O efeito dos parâmetros instrumentais e o preparo das suspensões foram estudados em função do sinal analítico. Para a determinação de Cu, Fe e Zn, as amostras foram suspensas em uma solução de HNO3 2,0 mol L-1 e para a determinação de Mn, o krill foi suspenso em uma solução de HNO3 4,0 mol L-1. A precisão entre as replicas foi melhor que 5 %. A metodologia foi aplicada para a determi-nação direta de Cu, Fe, Mn e Zn em amostras de krill antártico, usando padrões aquosos no preparo das curvas analíticas. Os resultados obtidos estão concordantes com os encontrados na determinação por FAAS e ICP-AES, depois da digestão das amostras em um forno de microondas. Os limites de detecção foram 4,5; 1,0; 4,9 e 8,4 mig L-1 para Cu, Zn, Mn e Fe, respectivamente.365370Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

TV comunitaria: algunas reflexiones del proceso de gestión

Empezar a vislumbrar una tesis de grado es un ejercicio que desata múltiples sensaciones, se presenta como un desafío inabarcable cuando damos los primeros pasos y cuando estamos cerca de suponer el fin del recorrido, perdura (a pesar de los años que transcurren) un sentimiento de inabrazabilidad. Es que se convierte en una meta a largo plazo, que cuando nos pisa los talones, se nos dificulta concebirlo como posibilidad concreta. Esta tesis consolida una etapa en nuestras vidas, es la conclusión de un trabajo realizado durante un tiempo prolongado, en el que pusimos el cuerpo para aportar una nueva mirada sobre medios comunitarios, los que pocas veces son contemplados desde la dimensión de su gestión. Este trabajo de intervención significa un broche a una etapa de cambio y propone algo nuevo desde su materialidad: pretende dejar pistas para los que trabajen en medios de comunicación comunitarios y tomen el desafío de oponerse a la convención, a aquellos que apuesten a tomar un camino diferente para decir lo que piensan, para dejar su voz. En un momento donde el espacio público de expresión ha perdido terreno frente a los medios de comunicación comerciales y masivos, este trabajo viene a exponer la labor de un grupo de gente que decide cambiar, tomar el riesgo y llevar adelante un sueño. Estas personas -también a través del cuerpo- nos enseñan que es posible ofrecer un producto diferente. A lo largo de esta tesis podremos corroborar que no se trata de una labor sencilla, pero no por ello impensable. Nuestra producción, presenta las contingencias y obstáculos que debieron eludir para llevarlo adelante. Desarrolla además, las potencialidades que presentan como grupo, la capacidad para aunar fuerzas detrás de un objetivo común. Cuando la continuidad de las transmisiones trasciende el número de espectadores al que puedan llegar, cuando hacer agua en la cuestión técnicomaterial genera creatividad y alternativas, cuando la riqueza está en el hacer conjunto persiguiendo una idea que defender, es en ese momento cuando nos planteamos nuestra pregunta y vemos cuáles son los puntos significativos de este espacio como terreno de análisis.Facultad de Periodismo y Comunicación Socia

Direct analysis of Antarctic krill by slurry sampling: determination of copper, iron, manganese and zinc by flame atomic absorption spectrometry

Slurry sampling in combination with flame atomic absorption spectrometry was employed for the direct determination of four essential trace elements, namely Cu, Fe, Mn and Zn in Antarctic krill. The effect of instrumental operating conditions and slurry sampling preparation on the analytical signal was investigated. For the determination of Cu, Fe and Zn, samples were suspended in a solution containing 2 mol L-1 HNO3. In the case of Mn, 4 mol L-1 HNO3 was necessary for the preparation of the slurry. The precision between sample replicates was better than 5%. The method was applied to the direct determination of Cu, Fe, Mn and Zn in Antarctic krill samples using aqueous reference solutions to prepare the calibration curves. The results obtained were in good agreement with those achieved by FAAS and ICP-AES after microwave-assisted wet digestion of the krill samples. The detection limits were 4.5, 1.0, 4.9 and 8.4 mug L-1 for Cu, Zn, Mn and Fe, respectively

Inductively coupled plasma optical emission spectrometric determination of fifteen elements in dietary supplements: Are the concentrations declared in the labels accurate?

A study was carried out to establish a reliable procedure for determining 15 elements (As, Bi, Cd, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, Se, V and Zn) in different brands of dietary supplements purchased in Argentina and USA. Supplements were digested with HNO3 and H2O2 using an optimized microwave procedure. Inductively coupled plasma optical emission spectrometry (ICP OES) was selected for total element determination. The overall approach was tested in tablets of: (i) Se supplement, (ii) two multimineral supplements, (iii) cholesterol control tablets, (iv) multivitamins for men, and (v) a multivitamin+multimineral supplement. Arsenic, Cd and Pb concentrations were in all the analyzed samples below the detection limits for these elements (As, 1.2 µg g-1; Cd, 0.09 µg g-1 and Pb, 1.5 µg g-1). Elemental concentrations of the other elements investigated showed a great variability depending on the trade mark analyzed. Measured metal concentration ranged from 0.78±0.19 µg g-1 (Ni) to 13.5±0.7 % (Ca). Most abundant elements, detected as percentage were Ca, Mg and Fe. In general terms, the study evidenced that metal content reported by the manufacturer in labels of dietary supplements agree with found values. On the other hand, significant differences in metal concentration were found among tablets of the same bottle.Fil: Marrero, Julieta. Comision Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Gerencia Ciclo del Combustible Nuclear; ArgentinaFil: Jiménez Rebagliati, Raúl Alberto Jorge. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); ArgentinaFil: Leiva, Emanuel. Comision Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Gerencia Ciclo del Combustible Nuclear; ArgentinaFil: Londonio, Juan Agustín. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); ArgentinaFil: Smichowski, Patricia Nora. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Fractionation of metals and metalloids by chemical bonding from particles accumulated by electrostatic precipitation in an Argentine thermal power plant

A study was undertaken to evaluate the distribution of Al, As, Cr, Cu, Fe, Mn, Ni, Pb, Ti, V and Zn in fly ashes collected in the electrostatic precipitator of a thermal power plant in San Nicolás (Argentina). Five samples were collected during one week of operation. For the fractionation, the scheme applied consisted in extracting the elements in four fractions namely (i) soluble and exchangeable elements; (ii) carbonates, oxides and reducible elements; (iii) bound to sulfidic metals; and (iv) residual elements. Metals and metalloids at μg g− 1 level were determined in each fraction by inductively coupled plasma optical emission spectrometry (ICP OES). For validation, a standard reference material (SRM 1633 coal fly ash) from NIST was subjected to the same chemical sequential extraction procedure that the samples. X-ray diffraction powder (XRD) analysis and scanning electron microscopy (SEM) were used to characterize the major minerals present in the matrix. Total analyte concentration (in μg g− 1) varied from 10.6 for Pb to 17,622 for Al. Minimum and maximum concentrations (in μg g− 1) found in individual samples in the four fractions were: Al, 92.7–9668; As, < 0.3–143; Cr, 2.0–10.4; Cu, < 0.2–35.6; Fe, < 0.3–4992; Mn, < 0.1–128; Ni, < 0.3–139; Pb, < 0.5–9.1; Ti, < 0.3–2243; V, 17.0–112.9; and Zn, < 0.1–68.2. The leachability of the 11 elements under study proved to be different. Low percentages of Al (1%), V (7%) and Cr (8%) were detected in the most bioavailable fraction. Arsenic was found to be most abundant in the non-silicate phase, represented by the second and third fractions, while Cr, Fe, Ni, Pb and Zn were mostly associated to the residual fraction.Fil: Gómez, Darío. Comisión Nacional de Energía Atómica; ArgentinaFil: Dos Santos, Marina. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fujiwara, Fabián Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Polla, Griselda. Comisión Nacional de Energía Atómica; ArgentinaFil: Marrero, Julieta. Comisión Nacional de Energía Atómica; ArgentinaFil: Dawidowski, Laura. Comisión Nacional de Energía Atómica; ArgentinaFil: Smichowski, Patricia Nora. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Use of slurry sampling in the determination of Cu and Zn in antarctic limpets and Ni in river sediment by flame atomic absorption spectrometry

In order to demonstrate the feasibility of slurry sampling for environmental studies, different methodologies were developed for Cu and Zn in antarctic limpets and Ni in river sediment with FAAS detection. Studies focusing particle size, acid concentration, slurry stability, selectivity, among others were carried out in order to define the better conditions for slurry analysis. A study related to the depth profile for Ni in the Atibaia River sediment was made after optimization conditions for this element. For accuracy check, certified reference material was used as well as decomposition with microwave oven.756760Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq