Low-cost approach to increase the analysis throughput of bar adsorptive microextraction (BAµE) combined with environmentally-friendly renewable sorbent phase of recycled diatomaceous earth.

In this study, a novel apparatus for bar adsorptive microextraction (BAµE) using a voltage regulator was proposed as an alternative tool to improve the analysis throughput. In addition, recycled diatomaceous earth obtained as a brewery residue was employed as a biosorbent coating for the determination of methyl paraben, ethyl paraben, benzophenone and triclocarban in water samples by high-performance liquid chromatography-diode array detection (HPLC-DAD). The use of the extraction devices, comprised of floating adsorptive bars of 7.5mm length, in the extractions with magnetic stirrers linked to a voltage regulator enabled the analysis of multiple samples, simultaneously. The method optimization was carried out by univariate and multivariate analyses. The optimal conditions for the method were sample solution at pH 5, extraction time of 90min and liquid desorption in 100µL of acetonitrile:methanol (50:50, v/v) for 15min. The total sample preparation time was 17.5min per sample for a simultaneous batch of six extractions. The R2 values for the calibration curves obtained were higher than 0.9985. The limits of detection (LODs) varied from 0.19 to 2µgL-1 and the limits of quantification (LOQs) ranged from 0.63 to 6.9µgL-1. The method was applied to freshwater samples collected from Peri Lagoon (Florianópolis, SC, Brazil) and the relative recoveries ranged from 63% to 124% with relative standard deviations (RSDs) of < 20% (n = 2). The RSD values for the reproducibility of the performance of the magnetic stirrers and inter-device extraction efficiency were lower than 14% (n = 3) and 11% (n = 3), respectively.

Adsorption of copper in oxisol and alfisol / Adsorção de cobre em Latossolo Bruno e Nitossolo Vermelho

The accumulation of copper (Cu) in soil can provide input in excess of these elements in the food chain through the contamination of soil and water. The study of the chemical behavior of Cu is needed for the knowledge of mobility of these elements in the soil profile. The aim of this study was to know the background Cu concentration, to evaluate the effect of pH, ionic strength (FI) and to quantify the maximum adsorption capacity (CMA) of Cu in Oxisol and Alfisol. The adsorption rate was evaluated at pH 4.5, 5.5 and 6.5 and the FI 15 and 150 mmol L-1 of Ca(NO3)2. To quantify the CMA were used rates of Cu concentrations of 0, 0.075, 0.15, 0.30, 0.60, 1.5 mmol L-1, final soil: solution l: 100. Raising the pH value increased the adsorption of Cu and increasing the ionic strength of the solution didnt reduce the adsorption of Cu. The CMA calculated for Cu in Alfisol was 3354 mg kg-1. It was not possible to calculate the CMA in Oxisol.(AU)

O acúmulo de cobre (Cu) no solo pode proporcionar a entrada em excesso desse elemento na cadeia alimentar através da contaminação do solo e água. O estudo do comportamento químico do Cu torna-se necessário para o conhecimento da mobilidade desse elemento no perfil do solo. O objetivo desse trabalho foi conhecer os teores nativos de Cu, avaliar o efeito de pH, força iônica (FI) e quantificar a capacidade máxima de adsorção (CMA) de Cu em Latossolo Bruno (LB) e Nitossolo Vermelho (NV). A adsorção foi avaliada em pH 4,5; 5,5 e 6,5 e na FI de 15 e 150 mmol L-1 de Ca(NO3)2. Para quantificar a CMA foram utilizadas doses de Cu nas concentrações de: 0, 0,075, 0,15, 0,30, 0,60, 1,50 mmol L-1, relação solo:solução final de 1:100. A elevação do valor de pH aumentou a adsorção de Cu e o aumento da força iônica da solução não diminuiu a adsorção de Cu. A CMA calculada para Cu no NV foi de 3354 mg kg-1. Não foi possível calcular a CMA para Cu no LB.(AU)

Adsorption of copper in oxisol and alfisol / Adsorção de cobre em Latossolo Bruno e Nitossolo Vermelho

The accumulation of copper (Cu) in soil can provide input in excess of these elements in the food chain through the contamination of soil and water. The study of the chemical behavior of Cu is needed for the knowledge of mobility of these elements in the soil profile. The aim of this study was to know the background Cu concentration, to evaluate the effect of pH, ionic strength (FI) and to quantify the maximum adsorption capacity (CMA) of Cu in Oxisol and Alfisol. The adsorption rate was evaluated at pH 4.5, 5.5 and 6.5 and the FI 15 and 150 mmol L-1 of Ca(NO3)2. To quantify the CMA were used rates of Cu concentrations of 0, 0.075, 0.15, 0.30, 0.60, 1.5 mmol L-1, final soil: solution l: 100. Raising the pH value increased the adsorption of Cu and increasing the ionic strength of the solution didnt reduce the adsorption of Cu. The CMA calculated for Cu in Alfisol was 3354 mg kg-1. It was not possible to calculate the CMA in Oxisol.

O acúmulo de cobre (Cu) no solo pode proporcionar a entrada em excesso desse elemento na cadeia alimentar através da contaminação do solo e água. O estudo do comportamento químico do Cu torna-se necessário para o conhecimento da mobilidade desse elemento no perfil do solo. O objetivo desse trabalho foi conhecer os teores nativos de Cu, avaliar o efeito de pH, força iônica (FI) e quantificar a capacidade máxima de adsorção (CMA) de Cu em Latossolo Bruno (LB) e Nitossolo Vermelho (NV). A adsorção foi avaliada em pH 4,5; 5,5 e 6,5 e na FI de 15 e 150 mmol L-1 de Ca(NO3)2. Para quantificar a CMA foram utilizadas doses de Cu nas concentrações de: 0, 0,075, 0,15, 0,30, 0,60, 1,50 mmol L-1, relação solo:solução final de 1:100. A elevação do valor de pH aumentou a adsorção de Cu e o aumento da força iônica da solução não diminuiu a adsorção de Cu. A CMA calculada para Cu no NV foi de 3354 mg kg-1. Não foi possível calcular a CMA para Cu no LB.

Niobium(V) oxide coated on thin glass-ceramic rod as a solid phase microextraction fiber.

The efficiency of niobium(V) oxide as a sorbent phase for solid phase microextraction (SPME) was investigated. The thin glass-ceramic rod was coated with niobium(V) oxide using chemical vapor deposition and Nb(2)O(5) as a chemical precursor. Optimum conditions for the preparation and conditioning of the fibers are presented. The fibers were used for the extraction of a mixture of alcohols and a mixture of phenols from the headspace samples. The results obtained proved the suitability of niobium(V) oxide as a new SPME fiber. The calibration graphs for alcohols and phenols in a concentration range of 50-1000 microgl(-1) were linear (r>0.995) and the detection limits were below 0.8 microgl(-1) level. The repeatability for one fiber (n=6) under similar conditions was between 3 and 10.4%. The fiber-to-fiber reproducibility (n=6) was between 5 and 15%.