This study developed a methodology for extracting and speciating CrIII and CrVI in sewage sludge by high performance liquid chromatography, inductively coupled plasma tandem mass spectrometry (HPLC-ICP-MS/MS). The optimal procedure was solid-liquid extraction in a water bath with stirring at 50 °C for 16 h and 50 mmol L−1 ethylenediaminetetraacetic acid (EDTA) extraction phase at pH 9.5. In the validated method, the recovery in the fortification experiment was greater than 70% and the relative standard deviation was less than 7%. Speciation analyses showed that all CrVI was spontaneously reduced to CrIII in the sludge sample. The limits of detection and quantification were 0.060 and 0.20 µg L−1, respectively, and the analyses of CrIII by means of ICP-MS/MS were linear from 0.20 to 50 µg L−1. The extraction efficiency of Cr specie in this validated method improved from 4.09 to 53.3% compared to the EPA 1311 method. The methodology was successfully applied to quantify CrIII in a sludge sample with a lower concentration than that established by European legislation 80568/4225/91.

2,4-Dichlorophenoxyacetic acid (2,4-D) has been one of the main herbicides used to control weeds, however, due to its high use it can promote episodes of environmental contamination. Therefore, this study aimed to optimize and validate the liquid-liquid extraction with low-temperature partition (LLE-LTP) and the quick, easy, cheap, effective, rugged, and safe (QuEChERS) methods for determining 2,4-D in water samples by high performance liquid chromatography with diode array detector. The recovery percentages of the two methodologies were close to 100 ± 3%, and the limits of quantification were 2.0 and 3.1 µg L-1 for LLE-LTP and QuEChERS, respectively. The methodologies were selective and presented linearity from 2.0-26.0 and 3.1-40.6 µg L-1 for LLE-LTP and QuEChERS, respectively. The LLE-LTP was better than QuEChERS due to a smaller number of steps, lower reagent consumption, higher concentration factor and a lower limit of quantification. The real samples did not reveal any environmental contamination episodes by 2,4-D.

In this work, the direct determination methodology of glyphosate and aminomethylphosphonic acid (AMPA) by high performance liquid chromatography (HPLC) using inductively coupled plasma with triple quadrupole mass spectrometer (ICP-MS/MS) was compared with the conventional method using diode array detector (HPLC-DAD). Both methods were selective, but the chromatographic analysis using ICP-MS/MS as detector was four times faster than DAD. The methodology using ICP-MS/MS as detector was linear from 27 to 218 µg L-1, while by the conventional method it was 1 to 8 mg L-1. Detection limits of the glyphosate achieved with the HPLC-ICP-MS/MS and HPLC-DAD methods were 8.2 and 300 µg L-1, respectively. The direct determination using ICP-MS/MS as detector showed a lower number of stages in sample preparation because it did not need the derivatization step. Seven real samples were analyzed by HPLC-ICP-MS/MS and the results showed that these analytes were not detected.

The chemical composition of Acacia mearnsii wood extract is described in this paper for the first time. This wood is cultivated in Brazil and has been used to complement the demand for hardwood in the pulp industry. In this study, we performed extractions with acetone (total extracts) and dichloromethane (lipophilic extracts responsible for the pitch formation), with the obtained percentages being 1.68 and 0.68%, respectively. The lipophilic extracts were derivatized and analyzed by Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS) before and after alkaline hydrolysis. The results showed that 57 compounds were detected in the lipophilic extracts and these are mainly constituted by fatty acids ca. 32.8 mg kg-1 and sterols 26.9 mg kg-1. These chemical classes have always been present in pitch deposits in the pulp industry. Therefore, these results may be used by pulp mills to establish strategies for pitch control and represent an important advance in the knowledge of A. mearnsii.

Polychlorinated dibenzo-p-dioxins and dibenzofurans are persistent organic pollutants which can mainly be found in the environment in water. These compounds are highly toxic and therefore developing new extraction methodologies that are simpler and cost less is highly desirable. This study aimed to optimize and validate the liquid-liquid extraction with low-temperature partition methodology of 2,3,7,8-tetrachlorodibenzo-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran in water samples. The optimum extraction conditions were 8.0 mL of the acetonitrile and 4.0 mL of the water, homogenized in a vortex for 1 min and then maintained at -20 ºC for 1 h. The analytes recovery percentage was close to 100% and relative standard deviation was less than 7%. The methodology was precise, accurate, linear at 2.4-5.4 µg L-1, and selective, with a quantification limit of 2.4 µg L-1. The optimized methodology was applied in ten real samples and the results showed that these analytes were not detected.

RESUMO Uma das grandes limitações do uso agrícola de alguns lodos de esgotos é a presença de clorobenzenos (CBs) que são tóxicos ao meio ambiente. O uso de técnicas de fitorremediação no lodo de esgoto pode ser uma importante alternativa para a degradação dessas substâncias no resíduo. Objetivou-se, neste trabalho, avaliar o tempo de cultivo de Pennisetum purpureum na redução das concentrações de 1,4-CB e 1,3,5-CB em lodo de esgoto. O experimento foi realizado em casa de vegetação, utilizando-se o delineamento em blocos casualizados. Os tratamentos corresponderam a cinco períodos do cultivo da Poaceae em parcelas de lodo de esgoto (30; 60; 90; 120 e 150 dias a partir do plantio de estacas) e uma testemunha (parcelas de lodo não cultivado). Aos 150 dias a testemunha, na camada de 0-20 cm, apresentou maiores concentrações de 1,3,5-CB, quando comparada à mesma camada do lodo cultivado. Já no lodo cultivado na camada de 10-20 cm, houve decréscimo das concentrações de 1,4-CB, enquanto, na camada de 20-30 cm, tanto as concentrações de 1,4-CB quanto de 1,3,5-CB diminuíram. As reduções observadas podem ser resultado das interações mutualísticas entre organismos decompositores e as raízes de P. purpureum, favorecendo o processo de remediação.

ABSTRACT One of the major limitations of sewage sludge agricultural use is the presence of chlorobenzenes (CBs), which are toxic to the environment. The use of techniques of sewage sludge phytoremediation can be an important alternative for the degradation of these substances in the waste. The aim of this study was to evaluate the effect of Pennisetum purpureum cultivation time on the reduction of the concentrations of 1,4-CB and 1,3,5-CB in sewage sludge. The experiment was conducted in a greenhouse, using a randomized block design. The treatments consisted of five periods of Poaceae cultivation in sewage sludge plots (30, 60, 90, 120 and 150 days) and a control (sludge plots not cultivated). At 150 days, the control, in the layer of 0-20 cm, showed higher concentrations of 1,3,5-CB, compared with the same layer of cultivated sludge. In the cultivated sludge, in the 10-20 cm layer, there was a decrease in the concentrations of 1,4-CB, while in the layer of 20-30 cm, both concentrations decreased. The observed reductions may be the result of mutualistic interactions between decomposer organisms and the roots of P. purpureum, favoring the decomposition process.

Sewage sludge is the residue produced by the wastewater treatment plants, which can be used as soil conditioner in agriculture. However, the current legislation recommends monitoring chemical contaminants such as polychlorinated biphenyls (PCBs). In this study, solid-liquid extraction with low temperature purification (SLE-LTP) was optimized and validated for monitoring six PCBs. The analyses were performed by gas chromatography and mass spectrometry. Sulfur interference was removed by 1.5 g of copper metal. The extraction was carried out using 6.50 mL isopropanol, 1.50 mL ethyl acetate, 0.1 g NaCl, 0.8 mL water and 15 min into ultrasound. Extraction percentages were between 82 and 94% and relative standard deviation ≤ 16% for low concentrations. Detection and quantification limits were 3.3 and 10 µg kg-1, respectively. The method was applied to sludge samples collected monthly in the wastewater treatment plant and PCB 52 was detected in six samples.

Parâmetros de maturação de frutos de tomate como pH, ºBrix, acidez e teores de licopeno e β-caroteno foram avaliados. Cinco agrotóxicos foram quantificados em extratos orgânicos de tomate em diferentes fases de maturação. A técnica de extração sólido-líquido com partição em baixa temperatura (ESL-PBT) foi utilizada para a obtenção desses extratos orgânicos. O efeito da matriz tomate foi calculado a partir dos resultados da análise por cromatografia gasosa com detector de captura de elétrons (CG-DCE). Correlações entre os parâmetros de maturação e efeito matriz foram estudadas. A correlação entre o teor de carotenoides e o efeito matriz foi elevada para todos os pesticidas estudados. Os resultados indicam que o efeito produzido pela matriz tomate está correlacionada com a presença de licopeno e β-caroteno em extratos orgânicos. A análise de componentes principais (PCA) mostrou que o licopeno, caroteno e a mistura de ambos têm efeitos significativos sobre a resposta cromatográfica de pesticidas.

Some parameters of tomato fruits ripening such as color, pH, ºBrix, acidity and lycopene and β-carotene content were evaluated during the ripening of fruits. Five pesticides were quantified in organic extracts derived from tomatoes at different stages of maturation. The solid-liquid extraction technique with partition at low temperature (SLE-PLT) was used to obtain these organic extracts. The matrix effect of tomato was calculated from the results of analysis by gas chromatography with electron capture detector (GC-ECD). Correlations between maturation parameters and matrix effect were performed. The correlation between the content of carotenoids and matrix effect was high for all pesticides studied. The results indicate that the effect produced by the tomato matrix is correlated with the presence of lycopene and β-carotene in organic extracts. The principal component analysis (PCA) showed that lycopene, carotene and the mixture of both have significant effects on the chromatographic response of pesticides, separating them into distinct groups.

O objetivo deste trabalho foi desenvolver um novo método espectrofotométrico, de elevada sensibilidade, eficiente e de fácil execução para determinar a atividade enzimática da endo-β-mananase em sementes. O método espectrofotométrico foi otimizado e aplicado em amostras de sementes de Butia capitata para determinar a localização da atividade enzimática em diferentes partes das sementes. O método consiste em extrair a enzima da semente e utilizá-la para hidrolisar o galactomanano Locust Bean Gum. Os açúcares redutores formados reagem com a hidrazida ácida p-hidroxibenzóico e são quantificados por espectrofotometria na região do visível. O método otimizado e validado apresentou baixos limites de quantificação para o açúcar redutor formado (0,6 µg de manose) e atividade da endo-β-mananase (1 mU). Apenas 5 mg de sementes em germinação são necessárias para executar o método.

The objective of this study was to develop a new, highly sensitive, efficient and easy touse spectrophotometric method to determine the enzymatic activity of endo-β-mannanase in seeds. The method was optimized and applied to determine the site of enzyme activity in different parts of seeds of Butia capitata. It consists in using the enzyme extracted from seeds to hydrolyze Locust bean gum galactomannan. The reducing sugars react with p-hydroxybenzoic acid hydrazide and are quantified by spectrophotometry in the visible region. The optimized and validated method showed low limits of quantification for the reducing sugars (0.6 µg mannose) and endo-β-mannanase activity (1 mU). Only 5 mg of germinating seeds are needed to perform the method.

Este trabalho apresenta a confirmação e otimização do método para derivatização de glifosato e ácido aminometilfosfônico (AMPA) utilizando cloroformiato de 9-fluorenilmetila (FMOC-Cl) avaliando-se os parâmetros: concentração de tampão borato e de FMOC-Cl, tempo de homogeneização e de reação, comprimento de onda e solvente de lavagem. A reação foi promovida com sucesso e o método é simples e de fácil execução pois utiliza cinco minutos de homogeneização e permite análises no ultravioleta imediatamente após o fim da reação.

This work presents the confirmation and optimization of the method for derivatization of glyphosate and aminomethylphosphonic acid (AMPA) using 9-fluorenylmethyl chloroformate (FMOC-Cl) evaluating the parameters: concentration of borate buffer and FMOC-Cl, homogenization time and of reaction, wavelength and solvent washing. The reaction was successfully promoted and the method is simple and easy to perform because it uses five minutes of homogenization and allows ultraviolet analysis immediately after the end of the reaction.

Nesse artigo, a técnica de extração sólido-líquido com purificação em baixa temperatura para a determinação de nove clorobenzenos (CB) em lodo de esgoto foi otimizada, validada e aplicada. Análises foram realizadas por cromatografia gasosa acoplada ao espectrômetro de massas. Depois da otimização da fase extratora, um planejamento fatorial foi usado para avaliar a influência de três variáveis, as quais foram pH, força iônica (NaCl) e tempo de homogeneização. O método mostrou ser seletivo, com limites de detecção e quantificação menores que 4,1 e 12,5 µg kg-1, respectivamente. As porcentagens de extração foram cerca de 70% e o desvio padrão relativo menor que 13% para os nove clorobenzenos analisados. Durante o monitoramento mensal os compostos 1,4-CB; 1,2,4-CB e 1,2,3-CB foram detectados em amostras de lodo de esgoto. Somente o composto 1,2,3-CB foi quantificado em concentrações superiores ao limite máximo aceitável para clorobenzenos em solos agrícolas condicionados com lodo de esgoto, mas sem considerar o efeito de diluição do lodo no solo

In this paper, the technique of solid-liquid extraction with purification at low temperature for the determination of nine chlorobenzenes (CB) in sewage sludge was optimized, validated and applied. Analyses were carried out by using gas chromatography coupled with mass spectrometry. After univariate optimization of the extraction phase, a factorial design was used in order to evaluate the influence of pH, ionic strength (NaCl) and homogenization time. The method proved to be selective, with detection and quantification limits less than 4.1 and 12.5 µg kg-1, respectively. Recoveries were about 70% and the relative standard deviation was less than 13% for the chlorobenzenes analyzed. During the monthly monitoring of sewage sludge samples 1,4-CB, 1,2,4-CB and 1,2,3-CB were detected. Only 1,2,3-CB was quantified in concentrations higher than the maximum acceptable limit for chlorobenzenes in agricultural soils amended with sewage sludge disregarding the dilution effect of the sludge on soil.

O efeito de matriz em análises por cromatografia gasosa é atribuído à presença de coextrativos na fase orgânica obtidos em processo de extração. Este trabalho relata o estudo da quantificação do aumento da resposta cromatográfica para quatro pesticidas em extratos orgânicos de tomate obtidos por extração sólido-líquido com purificação em baixa temperatura (ESL-PBT). Os pesticidas clorpirifós, l-cialotrina, cipermetrina e deltametrina apresentaram aumento da resposta cromatográfica depois da saturação do sistema cromatográfico com múltiplas injeções de extrato orgânico de tomate. Verificou-se também que quanto maior o tempo de retenção, maior o efeito de matriz, e o padrão interno reduz o efeito deste, mas não o elimina. O efeito de matriz medido pelas curvas analíticas (em acetonitrila e extrato da matriz) foi 27% para o clorpirifós, 46% para l-cialotrina, 96% para cipermetrina e 180% para deltametrina.

The matrix effect in gas chromatographic analysis is attributed to the presence of coextractives in organic phase obtained in the extraction process. This work reports the quantification study of increased chromatographic response of four pesticides in organic extracts of tomato extracted by solid-liquid extraction with low temperature purification (SLE-LTP). The pesticides chlorpyrifos, λ-cyhalothrin, cypermethrin and deltamethrin showed an increased chromatographic response after the saturation of the chromatographic system with multiple injections of organic extracts of tomato. It was also found that the greater the retention time, the greater the matrix effect, and that the internal standard reduces the matrix effect but does not eliminate it. The matrix effect measured by the analytical curves (in acetonitrile and matrix extract) was 27% for chlorpyrifos, 46% for λ-cyhalothrin, 96% for cypermethrin and 180% for deltamethrin.

This work was aimed on optimization of the matrix solid-phase dispersion (MSPD) technique using gas chromatography for analyzing residues of chlorpyriphos, λ-cyhalothrin, cypermethrin and deltamethrin in tomatoes. The results showed that silica was more efficient for the clean up of extracts, but florisil provided the highest recovery rates. A 2³ complete factorial design was carried out to evaluate the absorbent/sample ratio, presence of co-column (silica) and ultrasonic bath on the extraction rate. The percentage of extraction of the pesticides chlorpyriphos, λ-cyhalothrin, cypermethrin and deltamethrin were 64.7, 88.3, 99.2 and 89.2%, respectively, with relative standard deviations below 5%.

The lack of accuracy of a chromatographic method can be associated with the matrix effect. This effect is observed in pesticide quantification by gas chromatography when the chromatographic signals of standards prepared in solvents are compared with those of the analyte in extracts of complex matrices. In the competition between the matrix components and the pesticides for the active sites of the liner, a larger amount of pesticides is transferred to the column, giving apparent extractions above 100%. In this work, we discuss factors that contribute to the matrix effect and present some attempts to overcome the problem.