Sorption of sulfadiazine on Brazilian soils

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Antimicrobials, among them sulfonamides are widely used in veterinary medicine and can contaminate the environment. The degree to which antimicrobials adsorb onto soil particles varies widely, as does the mobility of these drugs. Sulfadiazine (SDZ) was used to study the adsorption-desorption in Brazilian soil-water systems, using batch equilibrium experiments. Sorption of SDZ was carried out using four types of soils. Adsorption and desorption data were well fitted with Freundlich isotherms in log form (r > 0.999) and (0.984 < r < 0.999), respectively. An adsorption-desorption hysteresis phenomenon was apparent in all soils ranging from 0.517 to 0.827. The experimental results indicate that the Freundlich sorption coefficient (K-F) values for SDZ ranged from 0.45 to 2.6 mu g(1-1/n) (cm(3))(1/n) g(-1). (C) 2012 Elsevier Ltd. All rights reserved.90620272034Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Sorption and desorption of sulfadimethoxine, sulfaquinoxaline and sulfamethazine antimicrobials in Brazilian soils

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Adsorption and desorption are important processes that influence the transport, transformation and bioavailability of antimicrobials in soils. The adsorption-desorption characteristics of sulfadimethoxine, sulfaquinoxaline and sulfamethazine in Brazilian soils (sandy, sandy-clay and clay) were evaluated using the batch equilibrium method. The sulfonamides were quantified in the soil solutions by a previously in house validated HPLC-PAD method. The adsorption/desorption data for the sulfonamides in soils fit the Freundlich isotherms well in the logarithmic form. The Freundlich adsorption coefficients ranged from 1.4 to 19.0 mu g(1 - 1)/ (n)(cm(3))(1 / n) g(-1), suggesting that all of the sulfonamides weakly adsorbed on the evaluated soils. The Freundlich desorption coefficients ranged from 0.85 to 24.8 mu g(1 - 1)/ (n)(cm(3))(1 / n) g(-1), indicating that the sulfonamides tend to be leached from soils with high sand and low organic carbon contents, suggesting that there is high potential for surface and groundwater contamination. (C) 2014 Elsevier B.V. All rights reserved.476406414Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [Proc. 2012/01767-0

Electroanalytical performance of self-assembled monolayer gold electrode for chloramphenicol determination

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Monolayers of 2-mercapto-5-methylbenzimidazole (MMB) were prepared on a polycrystalline gold electrode via a self-assembly process to produce a self-assembled monolayer. The resulting electrode was investigated by cyclic voltammetry and electrochemical impedance spectroscopy, and applied to the determination of chloramphenicol (CAP) in a pharmaceutical formulation using flow injection analysis along with amperometric detection. The amperometric cell was operated at -0.75 V (vs Ag/AgCl) at a flow rate of 3 mL min(-1). The method was applied to the determination of CAP in ophthalmic solutions, and its performance was compared to a previously validated HPLC method. The response to CAP is linear in the range from 0.050 to 1.000 A mu mol L(-1) (r = 0.9990), and the limit of detection is 44 A mu mol L(-1).16941732345351Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP