Dispersive micro-solid-phase extraction of herbicides in vegetable oil with metal-organic framework MIL-101.

Dispersive microsolid-phase extraction based on metal-organic framework has been developed and applied to the extraction of triazine and phenylurea herbicides in vegetable oils in this work. The herbicides were directly extracted with MIL-101 from diluted vegetables oils without any further cleanup. The separation and determination of herbicides were carried out on high performance liquid chromatography. The effects of experimental parameters, including volume ratio of n-hexane to oil sample, mass of MIL-101, extraction time, centrifugation time, eluting solvent, and elution time were investigated. The Student's t test was applied to evaluate the selected experimental conditions. The limits of detection for the herbicides ranged from 0.585 to 1.04 µg/L. The recoveries of the herbicides ranged from 87.3 to 107%. Our results showed that the present method is rapid, simple, and effective for extracting herbicides in vegetable oils.

Ultrasound-assisted ionic liquid-based homogeneous liquid-liquid microextraction high-performance liquid chromatography for determination of tanshinones in Salvia miltiorrhiza Bge. root.

The ultrasound-assisted ionic liquid-based homogeneous liquid-liquid microextraction has been developed and applied to the extraction of four tanshinones, including dihydrotanshinone, tanshinone I, cryptotanshinone and tanshinone IIA in Salvia miltiorrhiza Bge. root. High performance liquid chromatography was applied to the separation and determination of the analytes. The ionic liquid was used as extraction solvent and target analytes were extracted with help of ultrasound. Then, ion-pairing agent was added into the sample solution, which resulted in the formation of water-insoluble ionic liquid in the solution. The phase separation was performed by centrifugation. The extraction, concentration and purification of target analytes were performed simultaneously. The experimental parameters, including type and volume of ionic liquid, sample amount, the size of sample particle, pH value of extraction medium, extraction temperature, extraction time, amount of ion-pairing agent and centrifuging time, were investigated and optimized. The calibration curves showed good linear relationship (r>0.9997). The limits of detection and quantification were in the range of 0.052-0.093 and 0.17-0.31 µg mL(-1), respectively. The recoveries were between 70.45% and 94.23% with relative standard deviations lower than 5.31%. The present method is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with UAE and HRE. There was no obvious difference in the extraction yields of active constitutions obtained by the three extraction methods.