RESUMO
The AOAC 2007.1 quick, easy, cheap, effective, rugged, and safe official method, together with gas chromatography coupled to a triple quadrupole mass spectrometer was applied for the analysis of 38 multiclass pesticides from dried fruits typically cultivated and exported from Colombia: uchuva (Physalis peruviana), lulo (Solanum quitoense), guanabana (Anona muricata), and pitahaya (Hylocereus undatus). The whole method was validated in terms of matrix-matched calibration, matrix effect, and recovery using atrazine-d5 as internal standard, triphenylphosphate for quality control of the injection, and a proper mixture of analytes protectants. Matrix-matched calibration data were found satisfactory for all pesticides and dried fruits, reporting R2 values above 0.99. Matrix effect values evidenced the existence of such effect in most cases. The applied procedure gave satisfactory recovery percentages (70-120%) and relative standard deviation values (< 20%) for 92% of the 456 combinations pesticide/fruit studied (spiked levels of 25, 200, and 400 µg/kg). Finally, 20 real dried fruit samples were analyzed and residues of tebuconazole were found in two samples of uchuva at a concentration below the lowest calibration level of the method for one of them and at 10.8 ± 1.6 µg/kg for the other, being below or similar to the general maximum residue level established for monitoring purposes in food applications.
Assuntos
Annona/química , Contaminação de Alimentos/análise , Frutas/química , Praguicidas/análise , Cactaceae/química , Cromatografia Gasosa , Colômbia , Tamanho da Partícula , Physalis/química , Solanum/química , Propriedades de Superfície , Espectrometria de Massas em TandemRESUMO
In this work, a method has been applied and validated for the determination of a group of 35 multiclass pesticides in the minor tropical fruits rose apple/pomarrosa (Syzygium malaccense), starfruit/carambola (Averrhoa carambola), yoyomo (Spondias purpurea) and papayuela (Vasconcellea pubescens) cultivated and exported in Colombia. The AOAC 2007.1 QuEChERS method, that uses an acetic acid/acetate buffer, was applied together with gas chromatography coupled to a triple quadrupole mass spectrometer. The method was validated in terms of calibration, recovery at three levels of concentration and matrix effects (MEs). A mixture of analyte protectants was also used. A good linearity was obtained in all cases, while the study of the ME revealed the need of developing matrix-matched calibration for many pesticides. Recovery values were in the range 70-120% with relative standard deviation values less than 20% for most of the pesticides studied. The lowest calibration level was 5⯵g/kg. Several samples of each type were analysed.
Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Malus/química , Resíduos de Praguicidas/análise , Calibragem , Colômbia , Frutas/química , Frutas/metabolismo , Cromatografia Gasosa-Espectrometria de Massas/normas , Malus/metabolismo , Resíduos de Praguicidas/normas , Propoxur/químicaRESUMO
Nanomaterials have found an important place in Analytical Chemistry and, in particular, in Separation Science. Among them, metal-organic frameworks, magnetic and non-magnetic nanoparticles, carbon nanotubes and graphene, as well as their combinations, are the most important nanomaterials that have been used up to now. Concerning capillary electromigration techniques, these nanomaterials have also been used as both pseudostationary phases in electrokinetic chromatography (EKC) and as stationary phases in microchip capillary electrophoresis (CE) and capillary electrochromatography (CEC), as a result of their interesting and particular properties. This review article pretends to provide a general and critical revision of the most recent applications of nanomaterials in this field (period 2010-2017).
Assuntos
Eletroforese Capilar/métodos , Grafite/química , Nanopartículas Metálicas/química , Nanotubos de Carbono/química , Polímeros/química , Eletrocromatografia Capilar/métodos , Eletroforese Capilar/instrumentação , Eletroforese em Microchip/métodos , Sensibilidade e Especificidade , Propriedades de SuperfícieRESUMO
The dissipation/degradation of the pesticides dimethoate, terbufos, disulfoton, and pirimiphos-methyl were evaluated in milled toasted maize and wheat flour (gofio) during three months of storage. Their dissipation kinetics and residual levels were determined, as well as their possible decomposition into some of their main transformation products (disulfoton sulfoxide, terbufos sulfone and disulfoton sulfone). For this purpose, pesticide-free milled toasted maize and wheat samples were spiked with the pesticides, and they were then stored in the darkness at ambient temperature in a closed container to simulate current storage conditions of such packed food. A multiresidue analysis based on the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method was performed for the simultaneous determination of these pesticides and their metabolites. After three months of storage, the dissipation of residues ranged between 34% (pirimiphos-methyl) and 86% (disulfoton) for maize gofio and between 69% (terbufos) and 92% (disulfoton and pirimiphos-methyl) for wheat gofio. The results demonstrated that the degradation was slower in gofio than in wheat gofio and that none of the selected metabolites were detected in any of the samples. Dissipation curves of all studied pesticides fitted to a first-order decay curve in both types of cereals.