Separation, concentration and determination of chloramphenicol in environment and food using an ionic liquid/salt aqueous two-phase flotation system coupled with high-performance liquid chromatography

Ionic liquid–salt aqueous two-phase flotation (ILATPF) is a novel, green, non-toxic and sensitive samples pretreatment technique. ILATPF coupled with high-performance liquid chromatography (HPLC) was developed for the analysis of chloramphenicol, which combines ionic liquid aqueous two-phase system (ILATPS) based on imidazolium ionic liquid (1-butyl-3-methylimidazolium chloride, [C₄mim]Cl) and inorganic salt (K₂HPO₄) with solvent sublation. In ILATPF systems, phase behaviors of the ILATPF were studied for different types of ionic liquids and salts. The sublation efficiency of chloramphenicol in [C₄mim]Cl–K₂HPO₄ ILATPF was influenced by the types of salts, concentration of K₂HPO₄ in aqueous solution, solution pH, nitrogen flow rate, sublation time and the amount of [C₄mim]Cl. Under the optimum conditions, the average sublation efficiency is up to 98.5%. The mechanism of ILATPF contains two principal processes. One is the mechanism of IL–salt ILATPS formation, the other is solvent sublation. This method was practical when applied to the analysis of chloramphenicol in lake water, feed water, milk, and honey samples with the linear range of 0.5–500 ng mL⁻¹. The method yielded limit of detection (LOD) of 0.1 ng mL⁻¹ and limit of quantification (LOQ) of 0.3 ng mL⁻¹. The recovery of CAP was 97.1–101.9% from aqueous samples of environmental and food samples by the proposed method. Compared with liquid–liquid extraction, solvent sublation and ionic liquid aqueous two-phase extraction, ILATPF can not only separate and concentrate chloramphenicol with high sublation efficiency, but also efficiently reduce the wastage of IL. This novel technique is much simpler and more environmentally friendly and is suggested to have important applications for the concentration and separation of other small biomolecules.     

溶剂气浮法去除水中的刚果红的研究

以十六烷基三甲基溴化铵为表面活性剂, 与阴离子型染料刚果红形成缔合物, 对该缔合物的溶剂气浮过程进行研究. 研究多种参数对溶剂气浮过程的影响, 如气浮速率、共存溶质的量、pH等参数对溶剂气浮去除率的影响. 研究表明表面活性剂与染料的物质的量之比为2∶1, 约24 min水中刚果红的去除率可达97%;NaCl会大大降低溶剂气浮的去除率;溶剂气浮的速率随着气流速率的增加而增加, 但高速率反而降低溶剂的去除率;共存溶质乙醇存在会使去溶剂去除率降低, 有机溶剂的量对溶剂气浮影响较小;pH中性去除率最佳;考察了不同温度下溶剂气浮的热力学及动力学, 研究表明, 溶剂气浮过程遵从一级动力学, 计算了该过程中的气浮表观活化能为7.48 kJ/mol.     

精氨酸的溶剂浮选分离技术及其分离机制

以表面活性剂十二烷基苯磺酸为捕收剂(DBSA),二(2-乙基己基)磷酸酯(P204)为萃取剂,正庚烷为有机溶剂,采用溶剂浮选法对水溶液中精氨酸进行分离富集,并与气浮络合萃取法、泡沫浮选法和溶剂萃取法进行了比较.结果表明,在常温下,0.09 g/L精氨酸水溶液250 mL、初始pH 7.0,DBSA浓度0.15 g/L,正庚烷体积10 mL, P204体积4.5 mL,气体流量200 mL/min,溶剂浮选法分离水溶液中精氨酸的富集比为16.2,回收率为97.2%.溶剂浮选法分离精氨酸的动力学实验结果表明,精氨酸的溶剂浮选过程阶段性明显,大致可分为3个阶段,第一阶段和第二阶段都符合一级动力学方程,第三阶段符合零级动力学方程,探索了溶剂浮选法分离精氨酸的分离机制.     

The removal of humic acids from water by solvent sublation

The application of solvent sublation in the removal of humic acids was investigated in the present study. The humic acids (HA) were removed from an aqueous solution by solvent sublation of humic acid-hexadecylpyridium chloride (HPC) complex (sublate) into isopentanol. Several parameters were examined towards the optimization of humic acid removal; the dosage of a surfactant was found to be the major one, controlling the overall efficiency of the progress. The removal rate was somewhat enhanced by higher airflow rate and almost independent of the volume of the organic solvent floating on the top of the aqueous column. The effects of electrolytes (e.g., NaCl), nonhydrophobic organics (e.g., ethanol), and pH of the solution upon the process were studied. Under the optimized condition, the treatment performance was found to be very efficient, reaching almost 100%, indicating that solvent sublation can serve as a possible alternative technology for the removal of humic acids. The solvent sublation process follows first-order kinetics. A characteristic parameter, apparent activation energy of attachment of the sublate to bubbles, was estimated at a value of 9.48 kJ/mol. Furthermore, the simulation of a mathematical model with the experiments on the solvent sublation of humic acid-HPC was described here.     

Removal of Nitrobenzene,Isophorone, 2,6-Dinitrotoluene and 2,4-Dinitrotoluene from Aqueous Solution by Solvent Sublation

Nitrobenzene, isophorone, 2,6-dinitrotoluene and 2,4-dinitrotoluene were removed from aqueous solution by solvent sublation. The separation efficiencies of three solvents (4-methyl-2-pentanone, 1-octanol and paraffin oil) as the overlaying layer were compared. The rate of separation of these organic pollutants by solvent sublation depends strongly on the size of air bubbles, which is affected by the overlaying solvent, and concentrations of sodium dodecyl sulfate (NDS), inorganic and polar organic solute.     

溶剂气浮法分离水中的Zn离子的研究

以双硫腙为配体,溴化十六烷基三甲基铵（CTAB）为表面活性剂。对Zn离子在无机相中形成的Zn-双硫腙-CTAB体系的溶剂气浮进行了研究。研究表明表面活性剂与Zn离子的物质的量之比为5：1,约1h水中的锌离子去除率可达98％。0．5mol／L NaCl大大提高体系的溶剂气浮的去除率,溶剂气浮的速率随着气流速率的增加而增加,共存溶质乙醇存在会使去除率降低,有机溶剂的量对溶剂气浮影响较小,溶剂气浮过程遵从假一级动力学。考察了不同温度下溶剂气浮的回收速率,计算了该过程中的气浮表观活化能为9．037kJ／mol。     

Solvent sublation and spectrometric determination of iron(II) and total iron using 3-(2-pyridyl)-5,6-bis(4-phenylsulfonic acid)-1,2,4-triazine and tetrabutylammonium bromide.

Solvent sublation has been studied for the separation and determination of trace iron(II) in various kinds of water samples. A strongly magenta-colored anionic [Fe(FZ)3](4-) complex was formed at pH 5.0 upon adding 3-(2-pyridyl)-5,6-bis(4-phenylsulfonic acid)-1,2,4-triazine (ferrozine, FZ) to the sample solution. Tetrabutylammonium bromide (TBAB) was added in the solution to form the (TBA)4[Fe(FZ)3)] ion pair, and an oleic acid (HOL) surfactant was added. Then, the (TBA)4[Fe(FZ)3] ion pairs were floated by vigorous shaking in the flotation cell and extracted into methyl isobutyl ketone (MIBK) on the surface of the aqueous solution. The iron collected in the MIBK layer was measured directly by spectrophotometry and/or flame atomic-absorption spectrophotometry. Different experimental variables that may affect the sublation efficiency were thoroughly investigated. The molar absorptivity of the (TBA)4[Fe(FZ)3] ion pair was 2.8 x 10(4) l mol(-1) cm(-1) in the aqueous layer. Beer's law held up to 1.0 mg L(-1) Fe(II) in the aqueous as well as in the organic layers. The adopted solvent sublation method was successfully applied for the determination of Fe(II) in natural water samples with a preconcentration factor of 200. The application was extended to determine iron in pharmaceutical samples.     

Optimization of partitioning process parameters of chloramphenicol in ionic liquid aqueous two-phase flotation using response surface methodology

Ionic liquid aqueous two-phase flotation (ILATPF) is a green and effective separation and purification method, which combines solvent sublation and ionic liquid aqueous two-phase extraction system. This investigation attempts to study and optimize the partitioning conditions of chloramphenicol (CAP) in ILATPF. An experimental design of response surface methodology (RSM) was used to evaluate the influence of the variables, including the type of ionic liquid (IL), K₂HPO₄ concentration, flotation time and gas flow rate on CAP flotation. Quadratic polynomial models were adjusted to the data to predict the behavior of two responses, namely the partition coefficient (K) and sublation efficiency (E) of CAP. The optimal flotation conditions were found using [C₆mim]Cl, 0.74 g/mL K₂HPO₄, 50 min flotation time and 50 mL/min gas flow rate, which ensured K = 405.71 and E = 93.16 %. It was observed that the effect of the four factors on K and E of CAP was flotation time > gas flow rate > the type of IL > K₂HPO₄ concentration. The ILATPF was proved effective for CAP separation in aqueous phase, and RSM was revealed to be an appropriate and powerful tool for experimental design of CAP separation by ILATPF.     

Studies on the mechanism of Indigo Carmine removal by solvent sublation

Indigo Carmine (C16H8N2Na2O8S2), an anionic dye, was removed from aqueous solution by solvent sublation of Indigo Carmine-cetyltrimethylammonium bromide (CTAB) complex (sublate) into 2-octanol. A stoichiometric amount of surfactant (surfactant:dye=2:1) was demonstrated to be able to remove over 93% IC from the aqueous solution in 5 min. The apparent activation energy of attachment of the sublate to bubbles was calculated as 1.3 kJ/mol. Parameters were considered. At the same time, on the base of the complete transport mechanism, a mathematical model for the dye-surfactant complexation was obtained. Furthermore, the simulation of the mathematical and experimental data was made with good results.     

The kinetics and thermodynamics of surfactants in solvent sublation

Solvent sublation has been performed on very dilute solutions of one cationic surfactant, hexadecylpyridinium chloride (HPC), and one anionic surfactant, dodecylbenzenesulfonic acid (LBS). Some thermodynamic values were obtained, e.g. molecular areas, A₀, which are 50.0 and 47.7 Ų/molecule, respectively, for HPC and LBS, and free adsorption energies, ΔG°_ads, which are –33.17 and –43.58 kJ mol^–1, respectively, for HPC and LBS. The kinetics were determined for a range of temperatures and gas flow-rates. Although the processes of solvent sublation of the two surfactants obey first-order kinetics, the respective adsorption mechanisms of HPC and LBS in the solvent sublation process were different. The pH and the presence of KCl and ethanol had no effect on the solvent sublation of LBS. The apparent active energy was calculated as 8.11 kJ mol^–1.     

Study of a mathematical model of metal ion complexes in solvent sublation

Separation of metal ion complex, [(C(12)H(8)N(2))(3)Fe(2+)], with surfactant sodium dodecylphrate (DLS) complex from aqueous phase was carried out by solvent sublation, which obeys first-order kinetics. On the base of the complete transport mechanisms, the Langmuir adsorption, and the ion complex equilibrium in the aqueous phase, a mathematical model for the [(C(12)H(8)N(2))(3)Fe(2+)]-surfactant ion complex is obtained with the aid of the Mathematic 4.0 program, 4th Runge-Kutta method, and the Matlab programs. The effects of many parameters, such as K(a), K(l), K(ow), d(i), V(o), V(w), and Q(a), on solvent sublation are investigated. Furthermore, the simulation showed that the model is substantiated for experiments on the solvent sublation of the complex.     

Transport extraction for trace element separation and preconcentration

Summary A new method of sorbent supported transport extraction based on the use of open-cell polyurethane foam sorbents in solvent sublation separation has been developed. The method has been shown to be effective for the separation and preconcentration of radioiodine and/or stable iodine from 41 of deionized, drinking (tap) and surface (river) waters using N-cetylpyridinium chloride as the cationic surfactant and N₂ carrier gas as the bubbling medium. A transport extraction efficiency of about 94% was obtained in 60 to 90 min; a 300-fold preconcentration was found for radioiodine as measured by direct radioactivity counting. Both radioiodine and stable iodine can be back-extracted from the polyurethane foam support (e.g. into acetone with an efficiency of almost 95%).Part II: This journal (1993) 346:905On leave from the Institute of Radioecology and Applied Nuclear Techniques, P.O. Box A-41, 04061 Koice, Slovakia     

Separation of four flavonol glycosides from Solanum rostratum Dunal using aqueous two‐phase flotation followed by preparative high‐performance liquid chromatography

Aqueous two‐phase flotation followed by preparative high‐performance liquid chromatography was used to separate four flavonol glycosides from Solanum rostratum Dunal. In the aqueous two‐phase flotation section, the effects of sublation solvent, solution pH, (NH₄)₂SO₄ concentration in aqueous solution, cosolvent, N₂ flow rate, flotation time, and volumes of the polyethylene glycol phase on the recovery were investigated in detail, and the optimal conditions were selected: 50 wt% polyethylene glycol 1000 ethanol solvent as the flotation solvent, pH 4, 350 g/L of (NH₄)₂SO₄ concentration in aqueous phase, 40 mL/min of N₂ flow rate, 30 min of flotation time, 10.0 mL of flotation solvent volume, and two times. After aqueous two‐phase flotation concentration, the flotation products were purified by preparative high‐performance liquid chromatography. The purities of the final products A and B were 98.1 and 99.0%. Product B was the mixture of three compounds based on the analysis of high‐performance liquid chromatography at the temperature of 10°C, while product A was hyperoside after the identification by nuclear magnetic resonance. Astragalin, 3’‐O‐methylquercetin 3‐O‐β‐d ‐galactopyranoside, and 3’‐O‐methylquercetin 3‐O‐β‐d ‐glucopyranoside were obtained with the purity of 93.8, 97.1, and 99.2%, respectively, after the further separation of product B using preparative high‐performance liquid chromatography.     

溶剂浮选-HPLC法测定茵陈中滨蒿内酯的研究

摘要：建立茵陈中滨蒿内酯的溶剂浮选分离富集方法。方法 考察了浮选溶剂、氮气流速、试液 pH、浮选时间及电解质 NaCl 等因素对浮选效果的影响,优选出最佳浮选条件,并由高效液相色谱测定其含量。结果 对最佳条件下的浮选效果进行了评价。结论 加标回收率92.31 ~ 99.97 %; RSD = 3.20 %.溶剂浮选分离富集方法可行。     

The separation of rhodium and iridium by ion flotation

Mixtures of iridium(IV) and rhodium(III) as IrCl^2-₆ and RhCl^3-₆ are separated by ion flotation. The iridium(IV) is selectively floated from aqueous solutions of pH 2 and 0.05% Ce(IV) with either hexadecyltripropylammonium bromide (HTPAB) or hexadecyltributylammonium bromide (HTBAB). The rhodium(III) does not float under the same conditions. The floated iridium sublate is collected in n-butyl acetate without contamination by the unfloated rhodium. Data are presented also for the separation and recovery of the Ir(IV) and Rh(III) with the above surfactants, hexadecyltrimethyl-ammonium bromide (HTMAB) and hexadecyltriethylammonium bromide (HTEAB) from solutions of various sodium chloride and hydrochloric acid concentrations. The use of solvent sublation for recovering the floated iridium is examined. The separation is fast, practical, simple and does not require expensive reagents or apparatus. For these reasons, the separation of iridium and rhodium by ion flotation offers advantages over previous methods.     

Enantioseparation of α-cyclohexylmandelic acid by solvent sublation

Herein we focused on using a novel separation technology, solvent sublation, for the enantioseparation of α-cyclohexylmandelic acid (CHMA). The experiment was carried out in a conventional bubble column using d-iso-butyl tartrate (d-IBTA) and sodium dodecyl sulfate (SDS) as a chiral selector and surfactant, respectively (Fig. 7). Several important parameters influencing the separation performance, such as the type of organic phase, the pH in the aqueous phase, and the concentrations of CHMA, d-IBTA, and SDS were investigated. Under the optimal operating conditions, the enantiomeric excess and separation factor were 54.85% and 4.5, respectively. The yields of d-enantiomer and l-enantiomer were 82.20% and 38.94%, respectively. Finally, the thermodynamic properties of the separation were investigated, which indicated an enthalpy-controlled process. This technique is an efficient chiral separation method, with many advantages, such as low amounts of organic solvent and chiral selector required and easier realization of the multi-stage operation.     

溶剂浮选法分离富集污水中痕量羧酸类和胺类有机污染物的研究

本文报道了溶剂浮选法分离富集污水中痕量羧酸类有机污染物和胺类有机污染物的新方法。考察了溶液的pH值、通气速度、离子强度、浮选时间、相比以及不同溶剂对浮选效果的影响。在优化了浮选条件下溶剂浮选效率达到95％以上。采用本法对石化工业污水中的痕量羧酸类和胺类物质进行分离富集和鉴定,证明了该法的可行性。     

Micellar enhanced ultrafiltration of cadmium

The preconcentration of cadmium from aqueous colloid solution containing 8-hydroxyquinoline as extractant, laurylsulphate natrium as surfactant,n-butanol as co-surfactant was performed using micellar ultrafiltration technique. Filters with different pore size and materials were used to achieve a separation from liquid solutions. The cadmium recoveries depending on different conditions (pH, concentration of surfactant) were determined and the results are explained in the terms of colloidal parameters in the compare with the classical solvent extraction.     

Application of solvent sublation for the determination of organophosphorous pesticides in vegetables by gas chromatography with a flame photometric detector.

An effective method for separating and enriching organophosphorous pesticides (OPPs) from vegetables by solvent sublation and the OPPs determination by gas chromatography with flame photometric detector (GC-FPD) has been developed. The effects of organic solvent, nitrogen flow rate, pH of the solution, sublation time etc. on the sublation efficiency of OPPs were investigated in detail, and the optimal conditions of solvent sublation were selected. The floated product of vegetables in the optimal conditions was determined by GC-FPD. The limits of detection (LODs) ranged from 1.2 microg kg-1 (for dimethoate) to 3.5 microg kg-1 (for chlorpyrifos). The recoveries of spiked vegetable samples were from 81.3 to 98.9%, and RSD values were from 0.46 to 4.83%. The results show that this method is simple, sensitive and rapid.     

离子液体双水相溶剂浮选法分离/富集桑黄黄酮类成分

将亲水性离子液体氯化-1-丁基-3-甲基咪唑([C4mim]Cl)和K2HPO4形成的双水相体系与溶剂浮选结合,建立了分离/富集桑黄中总黄酮类成分的方法。考察了分相盐的种类和用量、样品量、溶液pH值、浮选时间和氮气流速对浮选效果的影响,并与双水相萃取进行比较。当浮选分相盐K2HPO4的质量浓度为50%、溶液pH=9.53、离子液体的用量为3 mL、浮选时间为50 min、氮气流速为30 mL/min时,浮选效率最佳,达到85.31%,富集倍数为8.59。离子液体双水相溶剂浮选法浮选效率高,富集倍数大,为中草药有效成分分离/富集提供了新方法。