Microextraction in packed sorbent for determination of sulfonamides in egg samples by liquid chromatography and spectrophotometric detection

The present work describes a successful application of microextraction packed sorbent and liquid chromatography with diode array detection (MEPS/LC-DAD) for simultaneous determination of the sulfonamides (sulfacetamide, sulfadiazine, sulfathiazole, sulfamethazine, sulfamethoxypiridazine and sulfamethoxazole) in egg samples. The MEPS variables (pH of the sample, draw-eject cycles, ionic strength, and desorption procedure) were optimized, in order to improve the sensitivity of the proposed method. The method was shown to be linear at concentrations ranging from 30 ng g-1 (limit of quantification, LOQ) to 300 ng g-1. This LOQ value is lower than those established as the maximum residue limit (MRL) for egg samples (100 µg kg-1). The accuracy values were adequate for all analytes (> 94%), as well as the inter-day precision data, with coefficient of variation lower than 10%. On the basis of analytical validation, the MEPS/LC methodology has been shown to be a promising alternative for analysis of sulfonamides in egg samples.O presente trabalho descreve a aplicação bem sucedida da microextração em sorvente empacotado e cromatografia líquida com detecção de arranjo de diodos (MEPS/LC-DAD) para a determinação simultânea das sulfonamidas (sulfacetamida, sulfadiazina, sulfatiazol, sulfametazina sulfametoxipiridazina e sulfametoxazol) em amostras de ovos. As variáveis MEPS (pH da amostra, número de ciclos aspirar/dispensar, força iônica e procedimento de dessorção) foram otimizados para aumentar a sensibilidade analítica do método. O método apresentou linearidade na faixa de concentração de 30 ng g-1 (limite de quantificação, LOQ) a 300 ng g-1. Este valor de LOQ é inferior ao limite máximo de resíduo (LMR) preconizado para sulfonamidas em amostras de ovos (100 µg kg-1). As taxas de recuperação foram adequadas para todos os analitos (> 94%), bem como os dados de precisão inter-ensaio, com coeficientes de variação inferiores a 10%. Com base na validação analítica, a metodologia MEPS/LC é adequada para a determinação de sulfonamidas em amostras de ovos.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)FAPES

HRGC study of sorption and desorption of atrazine, ametryn and metolachlor on Brazilian soils

The sorption and desorption of herbicides ametryn, atrazine and metolachlor were studied in five Brazilian soils with various organic matter contents using high resolution gas chromatography (HRGC). The regression lines generated presented a coefficient of determination > 0.964, which indicates a good fit of the data by the Freundlich equation. Sorption reached an apparent equilibrium in the soils within approximately 6 h. Hysteresis was observed in both sorption and desorption isotherms. Significant correlations were found among sorption of herbicides, organic matter, and cation-exchange capacity. No relationship was found between adsorption of the herbicides (ametryn, atrazine, and metolachlor) and their water solubility, pKa, and molecular mass, since these herbicides do not belong to the same chemical family. On account of this, the relationship between sorption and herbicide properties cited above was established only for s-triazines. The s-triazine adsorption showed a direct relationship with water solubility, pKa and molecular mass of these compounds on the studied soils

Butyl Methacrylate-Co-Ethylene Glycol Dimethacrylate Monolith for Online in-Tube SPME-UHPLC-MS/MS to Determine Chlopromazine, Clozapine, Quetiapine, Olanzapine, and Their Metabolites in Plasma Samples

This manuscript describes a sensitive, selective, and online in-tube solid-phase microextraction coupled with an ultrahigh performance liquid chromatography-tandem mass spectrometry (in-tube SPME-UHPLC-MS/MS) method to determine chlopromazine, clozapine, quetiapine, olanzapine, and their metabolites in plasma samples from schizophrenic patients. Organic poly(butyl methacrylate-co-ethylene glycol dimethacrylate) monolith was synthesized on the internal surface of a fused silica capillary (covalent bonds) for in-tube SPME. Analyte extraction and analysis was conducted by connecting the monolithic capillary to an UHPLC-MS/MS system. The monolith was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR). The developed method presented adequate linearity for all the target antipsychotics: R2 was higher than 0.9975, lack-of-fit ranged from 0.115 to 0.955, precision had variation coefficients lower than 14.2%, and accuracy had relative standard error values ranging from −13.5% to 14.6%, with the exception of the lower limit of quantification (LLOQ). The LLOQ values in plasma samples were 10 ng mL−1 for all analytes. The developed method was successfully applied to determine antipsychotics and their metabolites in plasma samples from schizophrenic patients