ABSTRACT
In this study, a simple and low-organic-solvent-consuming method combining an acetonitrile-partitioning extraction procedure followed by "quick, easy, cheap, effective, rugged and safe" cleanup with ionic-liquid-based dispersive liquid-liquid microextraction and high-performance liquid chromatography with diode array detection was developed for the determination of diflubenzuron and chlorbenzuron in grapes and pears. Ionic-liquid-based dispersive liquid-liquid microextraction was performed using the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate as the extractive solvent and acetonitrile extract as the dispersive solvent. The main factors influencing the efficiency of the dispersive liquid-liquid microextraction were evaluated, including the extractive solvent type and volume and the dispersive solvent volume. The validation parameters indicated the suitability of the method for routine analyses of benzoylurea insecticides in a large number of samples. The relative recoveries at three spiked levels ranged between 98.6 and 109.3% with relative standard deviations of less than 5.2%. The limit of detection was 0.005 mg/kg for the two insecticides. The proposed method was successfully used for the rapid determination of diflubenzuron and chlorbenzuron residues in real fruit samples.
Subject(s)
Benzene Derivatives/analysis , Diflubenzuron/analysis , Food Analysis/methods , Fruit/chemistry , Imides/analysis , Phenylurea Compounds/analysis , Acetonitriles/chemistry , Chemistry Techniques, Analytical , China , Chlorine/chemistry , Chromatography, High Pressure Liquid , Imidazoles/chemistry , Limit of Detection , Liquid Phase Microextraction , Pyrus , Reproducibility of Results , Solvents/chemistry , VitisABSTRACT
A novel and rapid ionic liquid-based dispersive liquid-liquid microextraction (IL-DLLME) method combined with liquid chromatography and a fluorescence detector for the analysis of ochratoxin A in rice wines is presented. The following parameters were systematically investigated: type and volume of ionic liquid, volume of dispersive solvent, salt addition, sample pH, and vortex time. Rice wine samples were first diluted to 18% alcohol with deionized water, and the pH was adjusted to 3.0. A DLLME procedure was followed that included IL ([HMIM][PF6]) and ethanol as the extraction and dispersive solvents, respectively. Under the optimized experimental conditions, good linearity was obtained with a correlation coefficient (r) of 0.9998 and a limit of detection (LOD) of 0.04µgL(-1). The recoveries ranged from 75.9% to 82.1% with an RSD below 10.4%. The proposed method was successfully applied to analyse OTA samples from several rice wine brands collected in Guangdong province, China.
Subject(s)
Chromatography, High Pressure Liquid/methods , Liquid Phase Microextraction/methods , Ochratoxins/analysis , Oryza , Wine/analysis , China , Hydrogen-Ion Concentration , Ionic Liquids/chemistryABSTRACT
A novel, simple, and rapid method is presented for the analysis of aflatoxin B1, aflatoxin B2, and ochratoxin A in rice samples by dispersive liquid-liquid microextraction combined with LC and fluorescence detection. After extraction of the rice samples with a mixture of acetonitrile/water/acetic acid, mycotoxins were rapidly partitioned into a small volume of organic solvent (chloroform) by dispersive liquid-liquid microextraction. The three mycotoxins were simultaneously determined by LC with fluorescence detection after precolumn derivatization for aflatoxin B1 and B2. Parameters affecting both extraction and dispersive liquid-liquid microextraction procedures, including the extraction solvent, the type and volume of extractant, the volume of dispersive solvent, the addition of salt, the pH and the extraction time, were optimized. The optimized protocol provided an enrichment factor of approximately 1.25 and with detection of limits (0.06-0.5 µg/kg) below the maximum levels imposed by current regulations for aflatoxins and ochratoxin A. The mean recovery of three mycotoxins ranged from 82.9-112%, with a RSD less than 7.9% in all cases. The method was successfully applied to measure mycotoxins in commercial rice samples collected from local supermarkets in China.
