It is well known that selectivity of molecularly imprinted polymers (MIPs) depends on adequate choice of functional monomer before the experimental synthesis. Computational simulation seems to be an ideal way to produce selective MIPs. In this work, we have proposed the use of semi-empirical simulation to obtain the best monomer able to strongly interact with ciprofloxacin. Twenty functional monomers were evaluated through semi-empirical quantum chemistry method and three MIPs were synthesized using the monomers acrylamide (M5), acrylic acid (M4) and 1-vinylimidazole (M16), yielding the maximum adsorption capacities of 282.0, 223.8 and 202.5 μmol g−1, respectively, as predicted by the computational simulation. From competitive adsorption studies in the presence of structurally similar compounds, the MIP synthesized with acrylamide was found to possess higher specific selectivity factors (S) if compared to non-imprinted polymer (NIP), thus indicating good recognition selectivity for the ciprofloxacin.

Esse estudo descreve o desenvolvimento e otimização de um método de extração em fase solida (SPE) para análise dos filtros ultravioletas (UV): benzofenona-3 (BP-3), etilhexil salicilato (ES), etilhexil metoxinamato (EHMC) e octocrileno (OC) em matrizes ambientais. Um planejamento fatorial fracionário (PFF) 2(5-1) foi empregado na avaliação das variáveis significativas do método de extração. As condições experimentais otimizadas da avaliação estatística foram: capacidade do cartucho de 500 mL, eluente acetato de etila, metanol como solvente de lavagem (10% em água, v/v) and volume do eluente de 3 × 2 mL e pH 3. Os parâmetros analíticos avaliados foram satisfatórios, apresentando linearidade de 100 a 4000 ng L-1, recuperações para os quatro níveis de fortificação (Limite de Quantificação do Método, 200, 1000 e 2000 ng L-1) entre 62 e 107% com desvio padrão relativo menor que 14%. Os limites de quantificação foram encontrados na faixa de ng L-1, variando entre 10 e 100 ng L-1. O método proposto foi aplicado para a determinação dos quatro filtros UV em amostras de águas naturais.

This study describes the development and optimization of a solid-phase extraction (SPE) method for analysis of ultraviolet (UV) filters, benzophenone-3 (BP-3), ethylhexyl methoxycinnamate (EHMC), ethylhexyl salicylate (ES) and octocrylene (OC), in environmental matrices. A 2(5-1) fractional factorial design (FFD) was used to evaluate the significant variables for the extraction method. The optimized experimental conditions determined from the statistical evaluation were: breakthrough volume of 500 mL, eluent of ethyl acetate, wash solvent of methanol (10% in water, v/v), eluent volume of 3 × 2 mL and pH 3. The evaluated analytical parameters were satisfactory for the analytes and showed linearity between 100 and 4000 ng L-1, recoveries for four fortification levels (Method Quantification Limit, 200, 1000 and 2000 ng L-1) were between 62 and 107% with relative standard deviations less than 14%. Limits of quantification were in the ng L-1 range and were between 10 and 100 ng L-1. The proposed method was used to analyze four UV filters in natural water samples.

A quantificação de compostos butílicos de estanho (BTs) em matrizes ambientais pode ser afetada pela ocorrência de interferentes encontrados em matrizes complexas tais como sedimentos e tecidos biológicos. O presente estudo investigou o efeito matriz em procedimentos analíticos para quantificação e especiação de BTs (TBT, DBT e MBT) em sedimentos e em dois tecidos (brânquias e fígado) de peixe, utilizando a técnica de cromatografia a gás com detecção fotométrica de chama pulsante (GC-PFPD). Diferentemente dos sedimentos avaliados, um efeito matriz significativo foi observado para os tecidos de peixe investigados, indicando que a quantificação de BTs deve ser realizada através da curva construída na matriz para evitar, dessa forma, erros de quantificação e redução da precisão analítica.

Butyltin (BTs) quantification in environmental matrices can be affected by interfering species found primarily in complex matrices, such as sediment and biota tissues. This study investigated matrix effects in analytical procedures for butyltin (TBT, DBT and MBT) quantification and speciation in sediments and in two fish tissues (gill and liver) by gas chromatography with pulsed flame photometric detection (GC-PFPD) analysis. Unlike sediment samples, tissues exhibited a significant matrix effect, thus, the quantification should be made by curve over matrix to avoid quantification errors and loss of analytical accuracy.

Phytohormone analysis using liquid chromatography combined with tandem mass spectrometry is a very important tool for studies involving plant metabolism; however, this analysis can be affected by matrix composition. Although it is necessary to understand this effect to produce reliable results, it has been widely neglected in analyses of plant hormones. Leaf extracts from Bauhinia variegata were obtained by solvent extraction followed by solid-phase cleanup. The extract was analyzed with liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) in negative ionization mode, using the multiple reaction monitoring mode with two or three transitions to enhance analytical quality control. Although deuterated standards were used as surrogates, pronounced matrix effects were detected for phaseic acid (PA), abscisic acid (ABA) -glycosyl ester (ABA-GE) and dihydrophaseic acid (DPA), whereas ABA, neoPA and 7'-hydroxy-ABA (7'OHABA) showed negligible matrix effects. The method was validated using spiked samples and was applied to monitor ABA, PA, DPA, neoPA, 7´OHABA and ABA-GE on a daily basis. Analyte recoveries from spiked samples ranged from 67% to 87%. The highest leaf concentration of phytohormones was found at 2:00 pm and 5:00 pm, which represent typical day times related to the decrease of stomatal conductance. Despite the use of deuterated phytohormones as internal standards, we showed that the use of a calibration curve constructed with a matrix extract is mandatory for the reliable quantification of ABA and its metabolites, especially PA, ABA-GE and DPA. Daily variations in endogenous ABA leaf concentration were discussed.

O ermitão Clibanarius vittatus é um organismo típico de regiões intertidais estuarinas sendo considerado um possível bioindicador da presença de tributilestanho (TBT) nesses ambientes. Por esta razão, este estudo apresenta o desempenho analítico e a validação do método para quantificação de TBT em tecidos de C. vittatus por cromatografia gasosa com detector fotométrico de chama pulsante (GC-PFPD), após extração com solvente apolar (tolueno) e derivatização com reagente de Grignard. Os limites de detecção do método (LOD) foram 2,0 e 2,8 ng g-1 para TBT e DBT (dibutil estanho), respectivamente, e seus limites de quantificação (LOQ) 6,6 e 8,9 ng g-1 para TBT e DBT, respectivamente. O método foi aplicado em amostras do Estuário de Santos, Estado de São Paulo, Brasil. As concentrações de TBT e DBT variaram de 26,7-175,0 ng g-1 a 46,2-156,0 ng g-1, respectivamente. As concentrações encontradas saopreocupantes uma vez que efeitos tóxicos (tais como a alteração endócrina) têm sido relatados em outros organismos, mesmo em níveis inferiores aos registrados no presente estudo.

The hermit crab Clibanarius vittatus is a typical organism from intertidal regions being considered as a good bioindicator of tributyltin presence at these environments. Thus this study presents the analytical performance and validation method for TBT quantification in tissues of C. vittatus by gas chromatography with pulsed flame photometric detector (GC-PFPD) after extraction with an apolar solvent (toluene) and Grignard derivatization. The limits of detection of the method (LOD) were 2.0 and 2.8 ng g-1 for TBT and DBT (dibutyltin), respectively, and its limits of quantification (LOQ) were 6.6 and 8.9 ng g-1 for TBT and DBT, respectively. The method was applied to samples from Santos Estuary, São Paulo State, Brazil. TBT and DBT concentrations ranged from 26.7 to 175.0 ng g-1 and from 46.2 to 156.0 ng g-1, respectively. These concentrations are worrisome since toxic effects (such as endocrine disruption) have been reported for other organisms even under lower levels of registred at this study.

The aim of this work was to analyze 17 β estradiol and estrone, natural estrogenic hormones present in domestic effluents and animal excreta, in the public water supply system of Jaboticabal, SP. The results have shown the presence of estrogens in 22% of the samples in concentrations from 6,8 ng L-1 (treated water) to 30,6 ng L-1 (riverhead) for 17 β estradiol and 600 ng L-1 of estrone (stream), respectively. We concluded that animal wastes, discharges from the wastewater treatment station, and discharges of domestic effluent without treatment from rural proprieties were probably the cause of this contamination.