Effective on‐line high‐speed shear dispersing emulsifier technique coupled with high‐performance countercurrent chromatography method for simultaneous extraction and isolation of carotenoids from Lycium barbarum L. fruits

An efficient combination strategy based on high‐speed shear dispersing emulsifier technique and high‐performance countercurrent chromatography was developed for on‐line extraction and isolation of carotenoids from the fruits of Lycium barbarum. In this work, the high‐speed shear dispersing emulsifier technique has been employed to extract crude extracts using the upper phase of high‐performance countercurrent chromatography solvent system composed of n‐hexane?dichloromethane?acetonitrile (10:4:6.5, v/v) as the extraction solvent. At the separation stage, the high‐performance counter‐current chromatography process adopts elution–extrusion mode and the upper phase of the solvent system as stationary phase (reverse‐phase mode). As a result, three compounds including zeaxanthin, zeaxanthin monopalmitate, and zeaxanthin dipalmitate with purities of 89, 90, and 93% were successfully obtained in one extraction‐separation operation within 120 min. The targeted compounds were analyzed and identified by high‐performance liquid chromatography, mass spectrometry, and NMR spectroscopy. The results indicated that the present on‐line combination method could serve as a simple, rapid, and effective way to achieve weak polar and unstable compounds from natural products.     

Simultaneous separation and preconcentration of ultra-trace of Cu(II), Pb(II) and Zn(II) in water samples by air-assisted liquid–liquid microextraction prior to determination by graphite furnace atomic absorption spectrometry

A simple, rapid and efficient method has been developed for the extraction, preconcentration and determination of copper, lead and zinc ions in water samples by air-assisted liquid–liquid microextraction coupled with graphite furnace atomic absorption spectrometry (GFAAS). In the proposed method, much less volume of an organic solvent (in the order of some µL) was used as the extraction solvent in the absence of disperser solvent. Fine organic droplets were formed by sucking and injecting of the mixture of aqueous sample solution and extraction solvent with a syringe for several times in a conical test tube. After extraction, phase separation was achieved by centrifugation and the enriched analytes in the sedimented phase were determined by GFAAS. Several variables potentially affecting the extraction efficiency were investigated and optimized. Calibration graphs were linear in the concentration range of 45.0–1100 ng L^?1. Detection limits were in the range of 18.0–26.0 ng L^?1. The accuracy of the developed procedure was checked by analyzing NRCC-SLRS4 Riverine water as a certified reference material. Finally, the proposed method was successfully applied to determine the selected heavy metals in tap, surface and river water samples.     

A procedure for determination of cobalt in water samples after dispersive liquid–liquid microextraction

In this work, a procedure for preconcentration of cobalt using dispersive liquid–liquid microextraction (DLLME) with the reagent Br-TAO as complexing reagent was developed. The procedure is based on a ternary system of solvents, where appropriate amounts of the extraction solvent, disperser solvent and the chelating agent Br-TAO are directly injected into an aqueous solution containing Co(II). A cloudy mixture is formed and the ions are extracted in the fine droplets of the extraction solvent. After extraction, the phase separation is performed with a rapid centrifugation, and cobalt is determined in the enriched phase by FAAS. Under the optimized conditions, the detection limit obtained was 0.9 µg L^{− 1}. The enrichment factor and the consumptive index were 16 and 0.31 mL, respectively. The accuracy of the method was tested by the determination of cobalt in certified reference material of spinach leaves, NIST 1570a. The proposed procedure was successfully applied to the determination of cobalt in water samples.     

萃取分配极限推导证明

萃取分离是化学实验中常见的操作,依据多组分热力学中的分配定律,以拉格朗日乘子法推导并从理论上证明只有在均分萃取剂的情况下,才可使萃取效果最佳。且等均萃取的极限萃余率是与萃取剂物理性质、萃取剂用量等多方面因素有关。以实例讨论了不同因素,如萃取剂用量、萃取次数、分配系数对于萃取效果的影响。对于从事化学合成、分析、分离、化工等方向的科研工作者在指定萃取方案时,有一定的借鉴和指导意义,而且可以推广到稀释、固相分离等领域中。     

Extraction and preconcentration technique for triazole pesticides from cow milk using dispersive liquid-liquid microextraction followed by GC-FID and GC-MS determinations

A simple and rapid dispersive liquid-liquid microextraction (DLLME) technique coupled with gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS) was developed for the extraction, preconcentration, and analysis of triazole pesticides (penconazole, hexaconazole, tebuconazole, triticonazole, and difenoconazole) in cow milk samples. Initially to 5 mL milk sample, NaCl and acetonitrile were added as salting-out agent and extraction solvent, respectively. After manual shaking, the mixture was centrifuged. In the presence of sodium chloride, a two-phase system was formed: upper phase, acetonitrile containing triazole pesticides and lower phase, aqueous phase containing soluble compounds and the precipitated proteins. After the extraction of pesticides from milk, a portion of supernatant phase (acetonitrile) was removed, mixed with chloroform at microliter level and rapidly injected by syringe into 5 mL distilled water. In this process, triazole pesticides were extracted into fine droplets of chloroform (as extraction solvent). After centrifugation, the fine droplets of chloroform were sedimented in bottom of the conical test tube. Finally, GC-FID and GC-MS were used for the separation and determination of analytes in the sedimented phase. Some important parameters like type of solvent for extraction of pesticides from milk, salt amount, the volume of extraction solvent, etc., which affect the extraction efficiency, were completely studied. Under the optimum conditions, enrichment factors were in the range of 156-380. The linear ranges of calibration curves were wide and limits of detection (LODs) and limits of quantification (LOQs) were between 4-58 and 13-180 μg/L, respectively. This method is very simple and rapid, requiring <15 min for sample preparation.     

Determination of ropivacaine in human plasma using highly selective molecular imprint-based solid phase extraction and fast LC–MS analysis

A method for determining ropivacaine in human plasma using highly selective molecular imprint-based solid phase extraction and LC–MS analysis was developed. The imprinted extraction material was prepared using a structural analogue of ropivacaine as the template. The efficient sample cleanup achieved allowed single MS mode operation and analytical separation under isocratic conditions with a total separation time of less than two minutes. The absence of ion suppression was confirmed for both the m/z of ropivacaine and the m/z of the internal standard. The solid phase extraction protocol was optimised for elution of ropivacaine in a small volume of aqueous-rich solvent suitable for injection into a reversed phase LC–MS system. The final method measured trace levels of ropivacaine in human plasma with a limit of quantification of 2.5 nmol/L and interassay accuracy and precision of 101.7–104.4% and 2.1–7.2%, respectively.     

加速溶剂萃取-快速液相色谱法测定纺织品中烷基苯酚和烷基苯酚聚氧乙烯醚

建立了纺织品中烷基苯酚和烷基苯酚聚氧乙烯醚的加速溶剂萃取-快速液相色谱测定方法。加速溶剂萃取法基本实现了样品前处理的自动化,简化了操作流程;快速液相色谱分析方法(利用核壳型快速分析色谱柱)大大缩短了样品分析时间(色谱分析时间小于5 min)。该方法在提高工作效率的同时节省了有机溶剂,且易于在普通实验室普及的常规液相色谱仪上实现,具有较强的实用性。     

A liquid–liquid extraction technique for phthalate esters with water-soluble organic solvents by adding inorganic salts

In the presence of inorganic salts, the mixture solution of some water-soluble organic solvents and water can form two clearly separated phases. One is the organic solvent rich phase, the other is the water rich phase. In the phase separation process, hydrophobic solutes dissolved in the mixture solution such as phthalate esters can be extracted into the organic solvent rich phase quantitatively. Based on this phase separation phenomenon, a liquid–liquid extraction technique of phthalate esters using water-soluble organic solvents as organic phases was developed. Several important parameters affecting the extraction efficiency including the kind and the amount of water-soluble organic solvents, the kind and the amount of inorganic salts and the pH of the sample solutions were carefully studied. This new extraction technique has been applied to the HPLC analysis for water lixivium of plastic wrapping film. Under the optimized conditions, detection limits of 1.5, 2.3, 1.0, 2.6, 1.3 and 3.0 ng mL⁻¹ were obtained for diethylphthalate, di-n-propylphthalate, di-iso-butylphthalate, dicyclohexylphthalate, di-n-octylphthalate and di-n-nonylphthalate ester respectively. The strongpoints of this new liquid–liquid extraction technique are the easy phase separation, rapid partition equilibrium, less toxicity and very good compatibility with subsequent HPLC determinations.     

Development of a micro-mixer-settler for nuclear solvent extraction

Nuclear solvent extraction was traditionally performed with packed columns, pulse columns, mixer-settlers and centrifugal extractors. However for rapid separations at micro-flow level, micro mixer-settlers were desired and in the past, few of them were actually designed and operated in nuclear solvent extraction research. In the current era of micro-reactor and microchannel devices, there is a renewed interest for micro-mixer-settlers for costly solvents and specialty solutes where small flow-rate is not an issue. In this article, development of a simple but effective micro-mixer-settler for nuclear solvent extraction is reported. The developed unit was tested with 30% TBP/n-dodecane/nitric acid system and in both the regimes of mass transfer c → d (mass transfer from continuous phase to dispersed phase, also written as c → d) and d → c (mass transfer from dispersed phase to continuous phase, also written as d → c) nearly 100% efficiency was observed in extraction as well as stripping modes of operation.     

Rapid determination of triclosan in personal care products using new in-tube based ultrasound-assisted salt-induced liquid–liquid microextraction coupled with high performance liquid chromatography-ultraviolet detection

This paper describes the development of a novel, simple and efficient in-tube based ultrasound-assisted salt-induced liquid–liquid microextraction (IT-USA-SI-LLME) technique for the rapid determination of triclosan (TCS) in personal care products by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. IT-USA-SI-LLME method is based on the rapid phase separation of water-miscible organic solvent from the aqueous phase in the presence of high concentration of salt (salting-out phenomena) under ultrasonication. In the present work, an indigenously fabricated home-made glass extraction device (8-mL glass tube inbuilt with a self-scaled capillary tip) was utilized as the phase separation device for USA-SI-LLME. After the extraction, the upper extractant layer was narrowed into the self-scaled capillary tip by pushing the plunger plug; thus, the collection and measurement of the upper organic solvent layer was simple and convenient. The effects of various parameters on the extraction efficiency were thoroughly evaluated and optimized. Under optimal conditions, detection was linear in the concentration range of 0.4–100 ng mL⁻¹ with correlation coefficient of 0.9968. The limit of detection was 0.09 ng mL⁻¹ and the relative standard deviations ranged between 0.8 and 5.3% (n = 5). The applicability of the developed method was demonstrated for the analysis of TCS in different commercial personal care products and the relative recoveries ranged from 90.4 to 98.5%. The present method was proven to be a simple, sensitive, less organic solvent consuming, inexpensive and rapid procedure for analysis of TCS in a variety of commercially available personal care products or cosmetic preparations.     

Automated continuous monitoring of drug dissolution process using a flow injection on-line dialysis sampling – solvent extraction separation spectrophotometric system

A flow injection (FI) system was developed incorporating on-line solvent extraction separation and stopped-flow dialysis systems for automated continuous monitoring of multi-vessel drug dissolution processes. The system employed PTFE pump tubes for solvent delivery, and combined a coaxial phase segmentor, conical cavity gravitational phase separator with a microdialysis sampling system to produce a reliable extraction system capable of stable non-stop operation over extended period of time. The system was evaluated for continuous monitoring in multi-vessel drug dissolution testing of ethambutol hydrochloride tablets using bromocresol green as reagent and chloroform as extractant. With the six-vessel dissolution system used, a sampling frequency of 15/h for each dissolution vessel was achieved with a total of 90 determinations per hour, giving an average precision of 3.6% RSD (n = 11). Results showed good agreement with those obtained using the Chinese Pharmacopoeia standard method. Received: 11 November 1998 / Revised: 18 January 1999 / Accepted: 22 January 1999     

Solvent extraction separation of iron(III) and aluminium(III) from other elements with Cyanex 302

A rapid method was developed for the solvent extraction separation of iron(III) and aluminium(III) from other elements with Cyanex 302 in chloroform as the diluent. Iron(III) was quantitatively extracted at pH 2.0-2.5 with 5 x 10(-3) M Cyanex 302 in chloroform whereas the extraction of aluminium(III) was quantitative in the pH range 3.0-4.0 with 10 x 10(-3) M Cyanex 302 in chloroform. Iron(III) was stripped from the organic phase with 1.0 M and aluminium(III) with 2.0 M hydrochloric acid. Both metals were separated from multicomponent mixtures. The method was applied to the separation of iron and aluminium from real samples.     

Application of supercritical fluid extraction coupled with counter–current chromatography for extraction and online isolation of unstable chemical components from Rosa damascena

Supercritical fluid extraction (SFE) coupled with high‐speed counter‐current chromatography (HSCCC) was successfully used for the extraction and online isolation of the unstable compounds from Rosa damascene in a single extraction and separation operation in two stages. The solvent systems of SFE/HSCCC were optimized with the help of multiexponential function model. At the first stage, the upper phase of the solvent system of n‐butanol–tert‐butyl methyl ether–acetonitrile–0.1% aqueous TFA (1.7:1.0:0.8:4.0, v/v/v/v) was used as both the SFE entrainer and the HSCCC stationary phase, and the target compounds were eluted with the corresponding lower phase to separate the hydrophobic compounds. At the second stage, the upper phase of the solvent system of n‐hexane–ethyl acetate–methanol–water (3.2:1.0:2.8:2.6, v/v/v/v) was used as both the SFE entrainer and the HSCCC stationary phase, followed by elution with the corresponding lower phase to separate the moderate hydrophobic compounds. Six compounds including formononetin, delphinidin, cyaniding, 5,6,4′‐trihydroxy‐7,8‐dimethoxy flavone, 5,3′‐dihydroxy‐7,8‐dimethoxy flavone, and 5‐hydroxy‐6,7,8,3′,4′‐pentamethoxy flavone were successfully separated in one extraction–separation operation within 300 min. The targeted compounds were identified by MS and NMR spectroscopy. This research has opened up great prospects for industrial application of SFE/HSCCC to the extraction and separation of unstable compounds.     

火焰原子吸收光谱法研究三乙醇胺双水相体系对铁的萃取

研究了三乙醇胺(TEA)水溶液在电解质作用下的相分离及其通过形成TEA-Fe3+配合物实现三乙醇胺相对Fe3+的萃取,萃取过程将萃取剂和萃取溶剂合二为一。同时还讨论了表面张力、溶液提升率对火焰原子吸收光谱法(FAAS)测定三乙醇胺相中铁的影响。建立了TEA-K2HPO4-H2O双水相萃取、FAAS测定铁的新方法:在试液中加入1 mL三乙醇胺(1+1)和5 g K2HPO4后以水定容为10 mL,离心分离后用FAAS测定三乙醇胺相中的铁。线性范围20～240μg/L,检出限6.1μg/L(S/N=3),已用于自来水和井水中铁的萃取。     

Comparison and application of two microextractions based on syringe membrane filter

Two proposed syringe membrane filter solid phase microextraction and syringe membrane filter liquid/solid phase microextraction, coupled separately with high performance liquid chromatography, were developed for simultaneous enrichment and determination of the trace level of flavonoids in traditional Chinese medicine. In syringe membrane filter solid phase microextraction, the membrane of syringe membrane filter was served as a solid adsorption film to adsorb target analytes. And in syringe membrane filter liquid/solid phase microextraction, the membrane of syringe membrane filter was used as not only an adsorption phase, but also as a holder of extraction solvent to realize liquid‐solid synergistic extraction. The simple operation, rapid extraction, and little or no organic solvent consumption make the two approaches very interesting. To evaluate the two proposed approaches, the crucial parameters affecting the enrichment factors of target analytes were investigated and optimized, and the two microextractions were intercompared. Moreover, their microextraction mechanisms were analyzed and described. Under the optimized conditions, both the new approaches achieved good linearities, accuracies, precisions, and low limits of detection, and the two methods were successfully applied for concentration of the flavonoids in traditional Chinese medicines.     

Separation of phenolic acids from sugarcane rind by online solid‐phase extraction with high‐speed counter‐current chromatography

Sugarcane rind contains some functional phenolic acids. The separation of these compounds from sugarcane rind is able to realize the integrated utilization of the crop and reduce environment pollution. In this paper, a novel protocol based on interfacing online solid‐phase extraction with high‐speed counter‐current chromatography (HSCCC) was established, aiming at improving and simplifying the process of phenolic acids separation from sugarcane rind. The conditions of online solid‐phase extraction with HSCCC involving solvent system, flow rate of mobile phase as well as saturated extent of absorption of solid‐phase extraction were optimized to improve extraction efficiency and reduce separation time. The separation of phenolic acids was performed with a two‐phase solvent system composed of butanol/acetic acid/water at a volume ratio of 4:1:5, and the developed online solid‐phase extraction with HSCCC method was validated and successfully applied for sugarcane rind, and three phenolic acids including 6.73 mg of gallic acid, 10.85 mg of p‐coumaric acid, and 2.78 mg of ferulic acid with purities of 60.2, 95.4, and 84%, respectively, were obtained from 150 mg sugarcane rind crude extracts. In addition, the three different elution methods of phenolic acids purification including HSCCC, elution–extrusion counter‐current chromatography and back‐extrusion counter‐current chromatography were compared.     

固相萃取-液相色谱/质谱法同时测定食品中磺胺类人工合成甜味剂

采用超声波提取,阴离子交换固相萃取柱净化,液相色谱．质谱定量检测食品中3种磺胺类甜味剂。方法对固相萃取条件,包括提取溶剂、洗脱溶剂以及洗脱体积等条件进行了优化。方法对安赛蜜、糖精钠、甜蜜素的检出限低于10pg,平均回收率在88％以上。在0．01～50μg/mL范围内有良好的线性关系,相关系数大于0．9996。本方法可用于食品中磺胺类甜味剂的快速测定。     

固相萃取富集-高效液相色谱分离和测定邻甲苯胺和邻硝基甲苯

建立了以固相萃取技术进行富集 ,高效液相色谱进行分离和检测邻甲苯胺和邻硝基甲苯的方法。污染水中的邻甲苯胺和邻硝基甲苯采用Sep pakC1 8萃取柱进行固相萃取。色谱分离条件是 :Shim PackCLCODS(1 5 0mm× 4 .6mmid ,5 μm)柱为分析柱 ,甲醇 水 =60∶4 0 (V V)为流动相 ,流速为 1 .0mL min,邻甲苯胺和邻硝基甲苯的紫外检测波长分别为 2 3 0nm和 2 5 4nm ,本法具有良好的灵敏度和重现性。     

Microwave‐assisted extraction with water for fast extraction and simultaneous RP‐HPLC determination of phenolic acids in Radix Salviae Miltiorrhizae

An optimized microwave‐assisted extraction method using water (MAE‐W) as the extractant and an efficient HPLC analysis method were first developed for the fast extraction and simultaneous determination of D (+)‐(3,4‐dihydroxyphenyl) lactic acid (Dla), salvianolic acid B (SaB), and lithospermic acid (La) in Radix Salviae Miltiorrhizae. The key parameters of MAE‐W were optimized. It was found that the degradation of SaB was inhibited when using the optimized MAE‐W and the stable content of Dla, La, and SaB in danshen was obtained. Furthermore, compared to the conventional extraction methods, the proposed MAE‐W is a more rapid method with higher yield and lower solvent consumption with a reproducibility (RSD <6%). In addition, using water as extractant is safe and helpful for environment protection, which could be referred to as green extraction. The separation and quantitative determination of the three compounds was carried out by a developed reverse‐phase high‐performance liquid chromatographic (RP‐HPLC) method with UV detection. Highly efficient separation was obtained using gradient solvent system. The optimized HPLC analysis method was validated to have specificity, linearity, precision, and accuracy. The results indicated that MAE‐W followed by HPLC–UV determination is an appropriate alternative to previously proposed method for quality control of Radix Salviae Miltiorrhizae.     

RP-HPTLC densitometric determination and validation of vanillin and related phenolic compounds in accelerated solvent extract of Vanilla planifolia*

A simple, fast and sensitive RP-HPTLC method is developed for simultaneous quantitative determination of vanillin and related phenolic compounds in ethanolic extracts of Vanilla planifolia pods. In addition to this, the applicability of accelerated solvent extraction (ASE) as an alternative to microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE) and Soxhlet extraction was also explored for the rapid extraction of phenolic compounds in vanilla pods. Good separation was achieved on aluminium plates precoated with silica gel RP-18 F(254S) in the mobile phase of methanol/water/isopropanol/acetic acid (30:65:2:3, by volume). The method showed good linearity, high precision and good recovery of compounds of interest. ASE showed good extraction efficiency in less time as compared to other techniques for all the phenolic compounds. The present method would be useful for analytical research and for routine analysis of vanilla extracts for their quality control.