| A novel functional material which is named ionic liquids(ILs) is merging in the frame of the green chemistry in recent years.They emerge as possible "green" solvent and have a wide utilization in synthesis,catalysis, electrochemistry and analytical chemistry for its unique properties such as low volatility, wide liquid phase range, tunable viscosity, good chemical and thermal stability and excellent solubility for various compounds, furthermore, ILs are regarded as "designer solvent", because their physical and chemical properties can be selected by choosing the cationic or the anionic constituent. The ionic liquids have attracted increasing attention and are successfully and more frequently applied as replacing the volatile and toxic organic solvent in sample preparation.The research results showed the obvious excellence of high performance of extraction, simplicity, rapidness, low cost and environmentally-benign, combining extraction and concentration into one step when using the ILs in the sample preparation as extraction solvent.In this work, the application of ionic liquids-based sample pretreatment methods in herbal medicine and food sample were investigated. The major content was composed of review and research report. In the review section, development of the sample pretreatment technique in chromatographic analytical chemistry were summarized, and the basical information, characters and applications of some widely used sample pretreatments were detailedly introduced. This part also comprised a brief introduction of ionic liquids and its application in the extraction and analysis fields.In the research report section, determination of the flavonoids in the mulberry leaves and the rhododendron mucronatum leaves and the pyrethroid insecticides in the aqueous food samples by the ionic liquids-based sample preparation combined with high performance liquid chromatography(HPLC) were developed.1、ionic liquid-based ultrasonic-assisted extraction coupled with high performance liquid chromatography for sensitive determination of flavonoids in mulberry leavesIonic liquid-based ultrasonic-assisted extraction coupled with high performance liquid chromatography was first applied to isolate and determinate flavonoids in mulberry leaves. The1-Butyl-3-methylimidazolium chloride ([BMIM] Br) was selected as the extraction solvent. Three compounds (morin hydrate, quercetin and kaempferol) from the ionic liquids extract have been isolated by using a Phenomenex C18column with a gradient elution, the mobile phase was methano1-0.1%phosphoric acid. The flow rate was1.0mL·min-1, and the UV detection wavelength was set at365nm. The contents of morin hydrate, quercetin and kaempferol were quantitatived by the external standard method. The calibration curves for morin hydrate, quercetin, and kaempferol were linear between0.65-130μg·mL-1(r=0.9999),0.64-128μg·mL-1(r=0.9999),0.21-84μg·mL-1(r=0.9998), respectively. The limit of detection (LOD) was0.099μg·mL-1,0.13μg·mL-1, and0.064μg·mL-1, respectively. The recoveries of these three compounds ranged from90.00%to95.31%. The results indicated that the proposed method was simple, rapid, accurate, sensitive, low cost and environment-friendly, thus it provides a new and scientific means for assaying flavonoids in the mulberry leaves.2、ionic liquid-based ultrasonic-assisted extraction combined with high performance liquid chromatography for simultaneous determination of flavonoids in rhododendron mucronatum leavesA novel ionic liquid-based ultrasonic-assisted extraction (ILUAE) combined with re-phase high performance liquid chromatography tandem UV detection (HPLC-UV) was first developed to isolate and determinate flavonoids in rhododendron mucronatum leaves. The1-Butyl-3-methylimidazolium chloride ([BMIM] Br) aqueous solution was selected as the extraction solvent. The Rhododendron mucronatum leaves powder was mixed with the ionic liquid, then the active constituents were extracted from the sample with the assist of ultrasound in the bath of water. Some important factors that affecting the extraction efficiency, such as the type of extraction solvent, the concentration of ionic liquid and the solid liquid ratio, were optimised. Under the optimal extraction conditions, satisfying extraction result was obtained.Three compounds (rutin, quercetin and kaempferol) from the ionic liquid extract were separated within15minutes using a Phenomenex C18column under a gradient elution of acetonitrile-0.25%acetic acid aqueous solution. The flow rate was1.0mL·min-1, and the UV detection wavelength was355nm. The contents of rutin, quercetin and kaempferol were quantitatived by the external standard method. The calibration curves of rutin, quercetin, and kaempferol were linear between0.064-128μg·mL-1(r=0.9999),0.076-152μg·mL-1(r=0.9999),0.064-128μg·mL-1(r=0.9999). respectively. The limit of detection (LODS, S/N=3) was0.0066μg·mL-1,0.0092μg·mL-1and0.0050μg·mL-1, respectively. The recoveries of these three compounds ranged from90.19%to96.63%. The experimental results suggested that the proposed method is an environment-friendly, easy to operation and efficient technique for sample preparation, thus it provides an alternative means for assaying flavonoids in the rhododendron mucronatum leaves.3、ionic liquids-based dispersive liquid-liquid microextraction followed by high performance liquid chromatography for the determination of pyrethriod insecticides in fruit juiceThe ionic liquids-based dispersive liquid-liquid microextraction(IL-DLLME) followed by high performance liquid chromatography(HPLC) with UV detection has been applied to the analysis of three pyrethroid insecticides (cyfluthrin,fenvalerate and permethrin) in fruit juice samples. In this method,50μL of1-octyl-3-methylimidazoliumhexafluorophosphate ([OMIm]PF6) as extraction solvent and1.00mL of methanol as dispersive solvent were rapidly injected into2.00mL sample solution by syringe.Cloudy solution was formed after shaken powerfully with hands.Phase separation was performed by centrifugation and the target analytes in the sediment phase were determined by HPLC-UV.Some important parameters affecting the extraction efficiency of the IL-DLLME, such as the type and volume of the extraction solvent and dispersive solvent.extraction time,were investigated and optimized.Under the optimized conditions, satisfied recoveries (86.67%-98.54%) were obtained for the analytes in the samples.The calibration curves in the concentration were linear which ranged from0.89～89μg·mL-1,1.05～105μg·mL-1,0.91～91μg·mL-1,(r2>0.999), respectively.The limits of detection (S/N=3) were0.20μg·mL-1,0.14μg·mL-1,0.22μg·mL-1. respectively.The experimental results suggested that the proposed method is an easy to operation,nontoxic, environmentally benign, efficient technique for sample preparation, thus it provides an alternative means for assaying pyrethroid insecticides in the aqueous food samples. |
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