| Objective: Liquid phase microextraction exhibits prominent superiority,for instance,wide range of application,high enrichment factor,simple to operate,low-cost,and less organic solvent consumption.However,part of conventional solvents which are used as extractants show toxic effects and have finite extraction efficiency.In order to overcome above shortcomings of conventional solvents and in respond to the call for “green chemistry”,this research article based on reverse micelle solution established greener and more efficient liquid phase microextraction methods,and the methods coupled with high performance liquid chromatography-ultraviolet detector were applied to extract,purify,concentrate and determine active compounds in complicated traditional Chinese medicine samples.The results of the methods compared with those obtained from liquid phase microextraction methods using conventional solvents,and to discuss the extraction mechanisms.Methods: Hollow fiber was used as the carrier of extractant and its wall pores and lumen were both filled with reverse micelle solution.Hollow fiber was put into sample phase containing analytes,then performing stirring extraction;the factors affecting extraction efficiency were optimized and methodology were investigated under the optimum extraction conditions,an approach of three-phase hollow fiber liquid-phase microextraction based on reverse micelle was established;under the optimum extraction conditions,the established method coupled with high performance liquid chromatography-ultraviolet detector(HPLC-UVD)was employed to simultaneous extraction,enrichment,and determination of four cinnamic acids(caffeic acid,p-hydroxycinnamic acid,ferulic acid,and cinnamic acid)from Chuanxiong Rhizoma medical material and Mai-luo-ning injection.Moreover,the results of the newly established method were compared with those of two-phase hollow fiber liquid-phase microextraction approach based on conventional organic solvent to explore the extraction mechanism.The hollow fiber which pores and lumen were respectively filled with reverse micelle solution and deep eutectic solvent was put into sample phase containing analytes,then performing stirring extraction;parameters affecting the extraction efficiency were optimized and methodology were investigated under the optimum extraction conditions,a method of four-phase hollow fiber liquid-phase microextraction based on reverse micelle/deep eutectic solvent was established;The novel method at its optimum extraction conditions combined with HPLC-UVD was applied for the simultaneous extraction,enrichment and determination of four cinnamic acids from Chuanxiong Rhizoma medical material and Mai-luo-ning injection and the results were compared with those of hollow fiber liquid-phase microextraction method based on 7 mmol/L reverse micelle as extractant and strong alkaline solution as acceptor phase.Reverse micelle solution was used as extractant,added into sample phase containing analytes,manual shaking accelerated dispersive extraction process.The extraction parameters affecting extraction efficiency were optimized and methodology was investigated under the optimum extraction conditions,an approach of three phase dispersive liquid-liquid microextraction based on reverse micelle was established;the new method combined with HPLC-UVD for the simultaneous extraction,enrichment and determination of four cinnamic acids from Chuanxiong Rhizoma and Angelicae Sinensis Radix medical materials and the results were compared with those obtained from dispersive liquid-liquid microextraction using conventional solvent,to discuss the extraction mechanism.Results: The optimum extraction conditions of three-phase hollow fiber liquid-phase microextraction approach based on reverse micelle: 7 mmol/L of reverse micelle solution formed by dissolving tricaprylylmethylammonium chloride in n-heptanol as extractant,sample phase p H was 5 with salt concentration was 0,stirring rate was 800 rpm,extraction time was 30 min;enrichment factors of caffeic acid,p-hydroxycinnamic acid,ferulic acid,and cinnamic acid were respectively 50,69,60 and 118;linear ranges were respectively 0.002-0.6 ?g/m L,0.001-0.3 ?g/m L,0.003-1 ?g/m L and 0.0016-0.48 ?g/m L,with correlation coefficients ranged from 0.9902 to 0.9987;limit of detections and limit of quantitations were respectively 0.1-0.4 ng/m L and 0.4-1.5 ng/m L;the relative standard deviations for intra-day precision and inter-day precision were 2.7%-9.1% and 3.0%-8.8%,respectively;the average recoveries were 85.5%-113.3%.The optimum extraction conditions of four-phase hollow fiber liquid-phase microextraction method based on reverse micelle/deep eutectic solvent: 7 mmol/L of reverse micelle solution formed by dissolving tricaprylylmethylammonium chloride in n-heptanol as extractant,deep eutectic solvent prepared by choline chloride and ethylene glycol with the molar ratio of 1:3 under heating condition as acceptor phase,sample phase p H was 7 with salt concentration was 0,stirring rate was 800 rpm,extraction time was 50 min;enrichment factors of caffeic acid,p-hydroxycinnamic acid,ferulic acid,and cinnamic acid were respectively 54,55,59 and 74;linear ranges were respectively 0.0056-5.6 ?g/m L,0.0032-3.2 ?g/m L,0.0048-4.8 ?g/m L and 0.004-4 ?g/m L,with correlation coefficients ranged from 0.9924 to 0.9999;limit of detections and limit of quantitations were 0.3-0.8 ng/m L and 1.0-2.5 ng/m L,respectively;the relative standard deviations for intra-day precision and inter-day precision were respectively 2.3%-6.3% and 2.8%-7.4%;the average recoveries were 84.7%-107.2%.The optimum extraction conditions of three phase dispersive liquid-liquid microextraction approach based on reverse micelle: 9 mmol/L of reverse micelle solution formed by dissolving tricaprylylmethylammonium chloride in n-heptanol as extractant,extractant volume was 50 ?L,sample phase p H was 6 with salt concentration was 0,extraction time was 20 s;the enrichment factors of caffeic acid,p-hydroxycinnamic acid,ferulic acid,and cinnamic acid were respectively 110,137,152 and 189;linear ranges were respectively 0.0024-0.96 ?g/m L,0.0012-0.36 ?g/m L,0.0012-0.84 ?g/m L and 0.0012-0.9 ?g/m L,with correlation coefficients ranged from 0.9947 to 0.9988;limit of detections and limit of quantitations were respectively 0.1-0.4 ng/m L and 0.4-1.5 ng/m L;the relative standard deviations for intra-day precision and inter-day precision were 0.9%-3.4% and 1.5%-5.7%,respectively;the average recoveries were 86.7%-108.9%.Conclusions: This paper respectively established three liquid phase microextraction approaches based on green solvents as extractant.Compared with their corresponding liquid phase microextraction methods using conventional extractant,the three methods shown the advantages of high extraction efficiency and environment-friendly,combined with HPLC-UVD were successfully applied to simultaneous extraction,enrichment and determination of four cinnamic acids from traditional Chinese medicines. |
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