RESUMO
In this study, a biosorbent material with characteristics for the adsorption of organic compounds was used for a cork pellet-based bar adsorptive microextraction technique, as a new greener alternative for the determination of organochlorine compounds. Aldrin, chlordane, dieldrin, endrin, lindane, 4,4-DDD, 4,4-DDE, 4,4-DDT, α-endosulfan and ß-endosulfan were analyzed in water samples (drinking water, stream water and river water) with separation/detection by gas chromatography and electron capture detection (GC/ECD). The parameters that can affect the sample preparation efficiency such as desorption solvent and time as well as extraction time and ionic strength were evaluated by multivariate and univariate designs. Cork pellets (10 × Ø 3 mm) were used for the extraction of 15 mL of sample in the optimal conditions: 60 min of agitation with no salt added to the sample, followed by desorption of the cork pellet with 120 µL of ethyl acetate for 30 min. The bar-to-bar RSD out with five different bars showed good results with RSD ≤ 15.6%, allowing the use of simultaneous extractions. LOD and LOQ values ranged from 3 to 15 ng L-1 and 10 to 50 ng L-1 respectively, and the determination coefficients were greater than 0.9869. The target analytes were not detected in the three analyzed samples. Therefore, the recovery study was performed fortifying the water samples. Analyte recovery ranged from 48.7 - 138.2% for drinking water, 40.2 - 128.2% for stream water and 67.5 - 128.7% for river water.
Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Hidrocarbonetos Clorados/análise , Microextração em Fase Líquida/métodos , Praguicidas/análise , Poluentes Químicos da Água/análise , Adsorção , Hidrocarbonetos Clorados/química , Hidrocarbonetos Clorados/isolamento & purificação , Limite de Detecção , Praguicidas/química , Praguicidas/isolamento & purificação , Reprodutibilidade dos Testes , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificaçãoRESUMO
The combination of two microextraction techniques (dispersive liquid-liquid microextraction [DLLME] and magnetic dispersive microsolid phase extraction [MDMSPE]) was developed and reported for atrazine and simazine preconcentration from wastewater samples. The proposal methodology involved the use of magnetite supports functionalized with different alkyl or phenyl groups. The magnetic adsorbents were synthesized by the solvothermal method assisted by microwave, characterized, and used in the sample preconcentration of atrazine and simazine. The method validation included parameters such as the wastewater matrix effect, repeatability, and recovery. The analyte separation and quantification were performed by high-performance liquid chromatography with ultraviolet detection (HPLC-DAD). Parameters, such as the polarity and mass of magnetic solids and pH, were evaluated to provide better extraction performance. The highest recoveries (> 95%) were obtained with 50 mg of the phenyl group support (CS2) at pH 5, using 5 mL of the sample and carbon tetrachloride and methanol, as extraction and dispersive solvents, respectively. The lowest limits of detection (LOD) achieved were 13.16 and 13.86 ng L-1, and the limits of quantification (LOQ) were 43.89 and 46.19 ng L-1 for simazine and atrazine, respectively, with repeatability (expressed as %RSD) below 5% in all cases. The developed method is simple, easy, and low cost for the analysis of two herbicides potentially dangerous for environmental and human health. Graphical abstract.
RESUMO
The determination of residues and contaminants in complex matrices such as in the case of food, environmental, and biological samples requires a combination of several steps to succeed in the aimed goal. At least three independent steps are integrated to provide the best available situation to deal with such matrices: (1) a sample preparation technique is employed to isolate the target compounds from the rest of the matrix; (2) a chromatographic (second) step further "purifies" the isolated compounds from the co-extracted matrix interferences; (3) a spectroscopy-based device acts as chromatographic detector (ideally containing a tandem high-resolution mass analyzer) for the qualitative and quantitative analysis. These techniques can be operated in different modes including the off-line and the on-line modes. The present report focus the on-line coupling techniques aiming the determination of analytes present in complex matrices. The fundamentals of these approaches as well as the most common set ups are presented and discussed, as well as a review on the recent applications of these two approaches to the fields of bioanalytical, environmental, and food analysis are critically discussed.