Zhifeng Guo - Cochemist

Extraction matrine from Radix Sopheorae Tonkinensis by non-supported liquid membrane extraction technology

Co-reporter:Zhifeng Guo, Caiyu Song, Lixia Zhang, Shuo Tian

Arabian Journal of Chemistry 2016 Volume 9(Supplement 1) pp:S144-S149

Publication Date(Web):September 2016

DOI:10.1016/j.arabjc.2011.02.028

Abstract

Non-Supported Liquid Membrane Extraction (NSLME) is a new development extraction technology based on Supported Liquid Membrane Extraction (SLME). Sample extraction assembly is composed of three phases: an acceptor phase: phosphate–sodium dihydrogen phosphate buffer solution at the bottom; an organic phase: chloroform applied as the non-supported liquid membrane in the middle layer; and a donor phase: aqueous solution samples containing alkaloids in the upper layer. The whole system is maintained stable by density difference among the three layers that avoided the mutual interferences. The alkaloid in the donor phase can spread to the underlying acidic acceptor phase, where it is able to form water soluble salt in the acid environment, and thus cannot return to the middle organic phase. Therefore, the transmission of alkaloid is a one-way path, and the extraction of alkaloids can be achieved and enriched. In this study, the extraction of alkaloid was carried out by using matrine aqueous solution as the donor phase, and the extraction quantity and efficiency were investigated by GC/MS. This study evaluated the relationship between extracted quantity and extraction time. The effects of extraction temperature, membrane thickness, pH value of acceptor phase on extraction quantity and efficiency were also studied, and the optimal extraction condition was found. The extracted quantity achieved the largest amount at 45 °C when pure phosphoric acid was applied as the acceptor phase; the organic solvent volume was 0.2 mL. The extraction of alkaloid from Radix Sophorae Tonkinensis was performed under the optimized condition. The extraction rate of matrine was up to 54% after a four-hour extraction. A huge advantage of NSLME technology is that the extracted alkaloid enjoyed high purity compared with that extracted by the traditional Liquid–Liquid Extraction (LLE).

Stability and performance study of newly developed emulsion prepared with polymeric rubber emulsifier and using the emulsion for nicotine extraction

Co-reporter:Zhifeng Guo, Jingjing Dong, Huidan Su, Ru Cai, Xiaoli Ma

Separation and Purification Technology 2015 Volume 156(Part 2) pp:617-624

Publication Date(Web):17 December 2015

DOI:10.1016/j.seppur.2015.10.057

•Using rubber as a new emulsifier for preparation of a new emulsion.•Study of factors of influence on the new emulsion stability.•The new emulsion rheological behavior.•The application of the new emulsion in extraction of nicotine.•Establishment of the optimal conditions on the membrane mass transfer rate.A stable water-in-oil (W/O) emulsion was prepared using polymeric additive as emulsifier instead of surfactant Span 80 (sorbitan monooleate) and kerosene as the organic membrane phase. The rubber emulsifiers were prepared using polybutadiene–styrene rubber (PBSR) or polybutadiene rubber (PBR) as the polymeric additive in this work. It was found that the rubber emulsifier acted like a surfactant in the emulsification process. The factors of influence of the W/O emulsion stability were investigated. The emulsion stability and mass transfer efficiency were assessed by measuring the concentration of nicotine in the internal strip and the external feed phase, respectively. The rheological behavior of W/O emulsion prepared with the rubber emulsifiers was also compared with that of W/O emulsion prepared with Span 80. It showed that the W/O emulsions prepared with the rubber emulsifiers were non-Newtonian when it dispersed in a continuous aqueous solution at low stirring speed. Applying the W/O emulsion for extraction of nicotine from real tobacco samples was carried out through dispersing it in the tobacco nicotine extractant aqueous solution. The results showed that nicotine was almost transferred from the feed to strip phase in 2 min and the efficiency of nicotine mass transfer was exceeded 99%.

Extraction of DL-anabasine from Alangium platanifolium root using an emulsion liquid membrane

Co-reporter:Zhifeng Guo, Huidan Su, Ru Cai and Xiaoli Ma

Analytical Methods 2015 vol. 7(Issue 5) pp:1860-1865

Publication Date(Web):07 Jan 2015

DOI:10.1039/C4AY02779E

An experimental study on the extraction of DL-anabasine from Alangium platanifolium root (APR) using an emulsion liquid membranes system (ELMs) has been reported. The ELMs was assembled using a butadiene styrene rubber emulsifier to prepare the emulsion, instead of surfactant Span 80, and acetic acid and kerosene as the carrier and diluent solution, respectively. The extraction time, pH, and volume ratio of the styrene rubber emulsifier in the membrane phase were examined, and the optimum reaction condition was determined. Under such a condition, an appropriate pH gradient in the feed and in the strip aqueous phase was set up. The selective separation of DL-anabasine from a matrix of raw APR or processed APR demonstrated that facilitated transport was achieved in the ELMs. A dynamic extraction of DL-anabasine provided a reasonable fit for the amount extracted versus time in the ELMs, which is based on mass transfer across the aqueous boundary layer, interfacial chemical reaction, and diffusion in the emulsion globule. Comparisons of the amount of DL-anabasine extracted from raw APR and from processed APR between the liquid–liquid extraction (LLE) and ELM extraction were performed for both qualitative and semi-quantitative analysis using GC/MS. The results showed that the relationship between the extraction amount of DL-anabasine and the extraction time is a bell-shaped curve, as the extraction amount of DL-anabasine reached its maximum at 2 min, and the amount then decreased with either increasing or decreasing extraction time. The amount of DL-anabasine extracted using ELMs is three times greater than that extracted using LLE.

Electrospun nanofibers prepared using polystyrene (PS) with polymeric additives for the determination of nicotine in cigarette mainstream smoke

Co-reporter:Zhifeng Guo, Xiaoyang Wu, Jingjing Dong, Hiudan Su and Ru Cai

Analytical Methods 2014 vol. 6(Issue 14) pp:5120-5126

Publication Date(Web):24 Apr 2014

DOI:10.1039/C4AY00165F

The objective of this paper was to use electrospun nanofibers as the adsorbents in solid phase extraction (SPE) to improve the extraction efficiency. The electrospun nanofibers were prepared in a lab using polystyrene (PS) along with the polymeric additives poly(methyl methacrylate) (PMMA) and co-poly(melamine–urea–formaldehyde) (MUF), and were put into a tip to form a SPE system. The polymeric additives could provide the nanofibers with more adsorption sites due to their chemically reactive hydroxyl groups, leading to a better adsorption rate during extraction. We used the nanofiber SPE system to extract nicotine from cigarette mainstream smoke. Isothermal adsorption and elution experiments showed that nicotine adsorption and organic solvent elution were good, and we achieved a high extraction efficiency. We also used the system to quantify the nicotine content of mainstream smoke. The results showed a correlation between cigarette price and nicotine content: the higher the price of a cigarette, the higher the nicotine content of its mainstream smoke.

Synthesis of molecularly imprinted co-polymers for recognition of ephedrine

Co-reporter:Shuo Tian, Zhifeng Guo, Xiaoxuan Zhang and Xiaoyang Wu

Analytical Methods 2013 vol. 5(Issue 19) pp:5179-5187

Publication Date(Web):19 Jul 2013

DOI:10.1039/C3AY41202D

In the present work, an improved approach for the preparation of molecularly imprinted polymers (MIPs) was proposed. The MIPs were prepared based on terpolymer copolymerization under acidic environmental conditions at room temperature and with a solvent eluting template, using ephedrine as the template, and melamine–urea–formaldehyde (MUF) as the terpolymer and also as a functional monomer. In this preparation protocol, the cross-linker was not added. Gas chromatography and mass spectrometry (GC/MS) were used to evaluate the adsorption properties and recognition mechanism of the ephedrine molecularly imprinted co-polymer (EMIP). The recognition property of EMIPs for ephedrine was investigated in depth with both static and dynamic methods using pseudo-ephedrine, another enantiomer of ephedrine, as the comparison compound. The EMIP's ability to bind ephedrine and pseudo-ephedrine was examined. Results showed that the EMIP had good recognition selectivity and binding affinity towards ephedrine, whereas its ability to bind pseudo-ephedrine was poor. The selectivity coefficient of EMIP for ephedrine with respect to pseudo-ephedrine is over seven. It indicated that it had a separation ability at the molecular configuration level. The solid-phase extraction (SPE) experiment showed that the EMIP was able to rebind and enrich ephedrine from the herb ephedra when used as the solid sorbent. The extraction results were compared with those of the liquid–liquid extraction (LLE), showing that the EMIP had a specific adsorption capacity for ephedrine. The amount of ephedrine extracted using SPE was 1.3 times higher than that using LLE.

Extraction of nicotine from local tobacco using double-supported liquid membranes technique

Co-reporter:Zhifeng Guo, Lei Wang, Caiyu Song, Lixia Zhang

Journal of Membrane Science 2010 Volume 356(1–2) pp:105-109

Publication Date(Web):1 July 2010

DOI:10.1016/j.memsci.2010.03.037

The objective of the study is to modify supported liquid membranes (SLMs) by designing a self-made double-supported liquid membrane (DSLMs). SLMs is a traditional extraction system that adopts organic solvent immersed membrane to separate the donor and acceptor phase. However, the system cannot maintain long extraction time due to the fast evaporation of the organic solvent where the easy volatile organic solvent is selected as organic phase. DSLMs system manages to solve the problem by enclosing the organic solvent between two membranes. This system has been successfully applied to the extraction of nicotine from local tobacco. The optical conditions for extraction nicotine were found and the amount of extracted nicotine were analyzed by GC/MS. Results showed that the extracting time could be held for 24 h and the amount of extracted nicotine got to 43%.

Preparation of molecularly imprinted adsorptive resin for trapping of ligustrazine from the traditional Chinese herb Ligusticum chuanxiong Hort.

Co-reporter:Zhi-Feng Guo, Ting-Ting Guo, Mufan Guo

Analytica Chimica Acta 2008 Volume 612(Issue 2) pp:136-143

Publication Date(Web):7 April 2008

DOI:10.1016/j.aca.2008.02.039

A highly selective molecularly imprinted adsorptive resin for ligustrazine was prepared by melamine–urea–formaldehyde (MUF) gel. In the experiments, two pieces of MUF gel were synthesized firstly; one was added ligustrazine hydrochloride as the template molecule in it to prepare the imprinted adsorptive resin, and the other was not. Scanning electron microscopy (SEM) revealed that both resins were the porous with a network structure whether or not it was added template molecule. The imprinted adsorptive resin had an absorbability of 85.22% measured by a 200 mg L−1 solution of ligustrazine hydrochloride at room temperature. The resin of MUF without template, on the other hand, displayed an adsorption capacity of almost zero. It illuminated the imprinted adsorptive resin formed ligustrazine recognition sites when the template molecule had been eluted. In the present paper, ligustrazine was effectively separated and enriched from herbs by using a solid-phase adsorptive column filled with the imprinted adsorptive resin. Its eluate, obtained from three kinds of solvents, was analyzed by GC–MS, and the results indicated that the imprinted adsorptive resin showed a high selectivity for ligustrazine. This is believed to be beneficial for extracting natural and highly purified ligustrazine.

Electrospun nanofibers prepared using polystyrene (PS) with polymeric additives for the determination of nicotine in cigarette mainstream smoke

Co-reporter:

Analytical Methods (2009-Present) 2014 - vol. 6(Issue 14) pp:

Publication Date(Web):

DOI:10.1039/C4AY00165F

The objective of this paper was to use electrospun nanofibers as the adsorbents in solid phase extraction (SPE) to improve the extraction efficiency. The electrospun nanofibers were prepared in a lab using polystyrene (PS) along with the polymeric additives poly(methyl methacrylate) (PMMA) and co-poly(melamine–urea–formaldehyde) (MUF), and were put into a tip to form a SPE system. The polymeric additives could provide the nanofibers with more adsorption sites due to their chemically reactive hydroxyl groups, leading to a better adsorption rate during extraction. We used the nanofiber SPE system to extract nicotine from cigarette mainstream smoke. Isothermal adsorption and elution experiments showed that nicotine adsorption and organic solvent elution were good, and we achieved a high extraction efficiency. We also used the system to quantify the nicotine content of mainstream smoke. The results showed a correlation between cigarette price and nicotine content: the higher the price of a cigarette, the higher the nicotine content of its mainstream smoke.

Synthesis of molecularly imprinted co-polymers for recognition of ephedrine

Co-reporter:

Analytical Methods (2009-Present) 2013 - vol. 5(Issue 19) pp:

Publication Date(Web):

DOI:10.1039/C3AY41202D

In the present work, an improved approach for the preparation of molecularly imprinted polymers (MIPs) was proposed. The MIPs were prepared based on terpolymer copolymerization under acidic environmental conditions at room temperature and with a solvent eluting template, using ephedrine as the template, and melamine–urea–formaldehyde (MUF) as the terpolymer and also as a functional monomer. In this preparation protocol, the cross-linker was not added. Gas chromatography and mass spectrometry (GC/MS) were used to evaluate the adsorption properties and recognition mechanism of the ephedrine molecularly imprinted co-polymer (EMIP). The recognition property of EMIPs for ephedrine was investigated in depth with both static and dynamic methods using pseudo-ephedrine, another enantiomer of ephedrine, as the comparison compound. The EMIP's ability to bind ephedrine and pseudo-ephedrine was examined. Results showed that the EMIP had good recognition selectivity and binding affinity towards ephedrine, whereas its ability to bind pseudo-ephedrine was poor. The selectivity coefficient of EMIP for ephedrine with respect to pseudo-ephedrine is over seven. It indicated that it had a separation ability at the molecular configuration level. The solid-phase extraction (SPE) experiment showed that the EMIP was able to rebind and enrich ephedrine from the herb ephedra when used as the solid sorbent. The extraction results were compared with those of the liquid–liquid extraction (LLE), showing that the EMIP had a specific adsorption capacity for ephedrine. The amount of ephedrine extracted using SPE was 1.3 times higher than that using LLE.