RESUMEN
Ultrasound-assisted extraction (UAE), cloud point extraction (CPE), and ultrasound back-extraction (UABE) techniques have been coupled for lixiviation, preconcentration, and cleanup of polybrominated diphenyl ethers (PBDEs) from milk samples for determination by gas chromatography-electron capture detection (GC-ECD). Physicochemical parameters that affect the efficiency of the extraction system were investigated using a design of experiments based on multivariate statistical tools, and considering the sample matrix along the development. The coupling of the leaching step, UAE, enhanced ca. 3.5 times the extraction efficiency of the former sample preparation methodology (CPE-UABE) leading to cleaner sample extracts suitable for GC analysis. Under optimum conditions, the proposed methodology exhibits successful performance in terms of linearity and precision, with recoveries in the range of 68-70% and LODs within the range 0.05-0.5 ng/g dry weight (d.w.). The proposed sample preparation methodology coupled three green analytical techniques. It expands the application frontiers of CPE for the analysis of biological samples by GC. The optimized methodology was used for determination of PBDEs in powder milk samples, from both commercial and human sources.
Asunto(s)
Tecnología Química Verde/métodos , Éteres Difenilos Halogenados/análisis , Leche/química , Sonicación/métodos , Animales , Fraccionamiento Químico , Cromatografía de Gases/métodos , Éteres Difenilos Halogenados/química , Éteres Difenilos Halogenados/aislamiento & purificación , Límite de Detección , Modelos Lineales , Reproducibilidad de los Resultados , Proyectos de InvestigaciónRESUMEN
In this research, firstly, the treatment of soil spiked with oxyfluorfen was studied using a surfactant-aided soil-washing (SASW) process. After that, the electrochemical treatment of the washing liquid using boron doped diamond (BDD) anodes was performed. Results clearly demonstrate that SASW is a very efficient approach in the treatment of soil, removing the pesticide completely by using dosages below 5 g of sodium dodecyl sulfate (SDS) per Kg of soil. After that, complete mineralization of organic matter (oxyflourfen, SDS and by-products) was attained (100% of total organic carbon and chemical oxygen demand removals) when the washing liquids were electrolyzed using BDD anodes, but the removal rate depends on the size of the particles in solution. Electrolysis of soil washing fluids occurs via the reduction in size of micelles until their complete depletion. Lower concentrations of intermediates are produced (sulfate, chlorine, 4-(trifluoromethyl)-phenol and ortho-nitrophenol) during BDD-electrolyzes. Finally, it is important to indicate that, sulfate (coming from SDS) and chlorine (coming from oxyfluorfen) ions play an important role during the electrochemical organic matter removal.
Asunto(s)
Electrólisis/métodos , Éteres Difenilos Halogenados/aislamiento & purificación , Contaminantes del Suelo/aislamiento & purificación , Suelo/química , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/métodos , Análisis de la Demanda Biológica de Oxígeno , Boro/química , Diamante/química , Electrodos , Oxidación-Reducción , Dodecil Sulfato de Sodio/química , Tensoactivos/químicaRESUMEN
Ultrasound leaching-dispersive liquid-liquid microextraction using solidification of floating organic droplet (USL-DLLME-SFO) technique is proposed for extraction and isolation of polybrominated diphenyl ethers (PBDEs) from sediment and further determination by gas chromatography-tandem mass spectrometry (GC-MS/MS). Parameters that affect the efficiency of the procedure were investigated by a full factorial (2(k)) screening design. Variables showing significant effects on the analytical responses were considered within a further central composite design (CCD). The optimization assays have led to following protocol: ultrasound assisted lixiviation of 1g sediment was carried out by using 1.2 mL MeOH. Further, the analytes were isolated from 0.4 mL of the extract using the DLLME-SFO technique. The microextraction was performed using 0.1 mL MeOH, 22 mg 1-dodecanol, 1 mL NaCl solution 6.15M and 4.4 mL ultrapure water as dispersive and extracting solvents, medium ionic strength and dispersant bulk, respectively. Under optimum conditions, the method exhibits good performance in terms of linearity and precision (RSD<9.2%), with recoveries above 71% and limits of detection (LODs) within the range 0.5-1.8 pgg(-1) dry weight (d.w.). Method validation was demonstrated through the analysis of environmental sediment samples in which PBDEs were detected and quantified. The presence of BDE-47, -100, -99 and -153 was reported within the concentration range of Asunto(s)
Cromatografía de Gases y Espectrometría de Masas/métodos
, Sedimentos Geológicos/química
, Éteres Difenilos Halogenados/análisis
, Éteres Difenilos Halogenados/aislamiento & purificación
, Microextracción en Fase Líquida/métodos
, Espectrometría de Masas en Tándem/métodos
, Argentina
, Contaminantes Ambientales/análisis
, Contaminantes Ambientales/aislamiento & purificación
, Límite de Detección
, Reproducibilidad de los Resultados
, Proyectos de Investigación
, Sonicación/métodos
RESUMEN
Ultrasound-assisted leaching-dispersive solid-phase extraction followed by dispersive liquid-liquid microextraction (USAL-DSPE-DLLME) technique has been developed as a new analytical approach for extracting, cleaning up and preconcentrating polybrominated diphenyl ethers (PBDEs) from sediment samples prior gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. In the first place, PBDEs were leached from sediment samples by using acetone. This extract was cleaned-up by DSPE using activated silica gel as sorbent material. After clean-up, PBDEs were preconcentrated by using DLLME technique. Thus, 1 mL acetone extract (disperser solvent) and 60 microL carbon tetrachloride (extraction solvent) were added to 5 mL ultrapure water and a DLLME technique was applied. Several variables that govern the proposed technique were studied and optimized. Under optimum conditions, the method detection limits (MDLs) of PBDEs calculated as three times the signal-to-noise ratio (S/N) were within the range 0.02-0.06 ng g(-1). The relative standard deviations (RSDs) for five replicates were <9.8%. The calibration graphs were linear within the concentration range of 0.07-1000 ng g(-1) for BDE-47, 0.09-1000 ng g(-1) for BDE-100, 0.10-1000 ng g(-1) for BDE-99 and 0.19-1000 ng g(-1) for BDE-153 and the coefficients of estimation were > or =0.9991. Validation of the methodology was carried out by standard addition method at two concentration levels (0.25 and 1 ng g(-1)) and by comparing with a reference Soxhlet technique. Recovery values were > or =80%, which showed a satisfactory robustness of the analytical methodology for determination of low PBDEs concentration in sediment samples.