Separation of perillyl alcohol from the peel of citrus unshiu by supercritical CO2 and preparative high-performance liquid chromatography

To separate perillyl alcohol (POH), a potential anti-cancer agent, the peel of citrus unshiu was extracted by supercritical CO₂ extraction (SCE) system at 50 ‡C, 200 bar and 6 kg CO₂/hr/kg sample. The extracts were partitioned by acetonitrile/hexane (90/10, vol%). POH was eluted in the acetonitrile phase. An open-tubular chromatography with silica gel (40–63 Μm) was used to purify POH from the acetonitrile phase. Mobile phase was hexane/ethyl acetate (90/10, vol%). To obtain POH in a pure form, finally preparative high-performance liquid chromatography was applied. The collection of POH from citrus unshiu peel was achieved on a laboratory-prepared Chromatographic column (300x3.9 mm) packed with 15 Μm C₁₈ preparative packings. The composition of mobile phase was water/acetonitrile (50/50, vol%). The flow rate of the mobile phase was 1 ml/min and UV wavelength was fixed at 205 nm. It was found that the total yield of POH was 1.6xl0^-3 (wt%) as the dry powder of citrus unshiu peel.     

Atrazine Molecular Imprinted Polymers: Comparative Analysis by Far-Infrared and Ultraviolet Induced Polymerization

Atrazine molecular imprinted polymers (MIPs) were comparatively synthesized using identical polymer formulation by far-infrared (FIR) radiation and ultraviolet (UV)-induced polymerization, respectively. Equilibrium binding experiments were carried out with the prepared MIPs; the results showed that MIP_uv possessed specific binding to atrazine compared with their MIP_FIR radiation counterparts. Scatchard plot’s of both MIPs indicated that the affinities of the binding sites in MIPs are heterogeneous and can be approximated by two dissociation-constants corresponding to the high-and low-affinity binding sites. Moreover, several common pesticides including atrazine, cyromazine, metamitron, simazine, ametryn, terbutryn were tested to determine their specificity, similar imprinting factor (IF) and different selectivity index (SI) for both MIPs. Physical characterization of the polymers revealed that the different polymerization methods led to slight differences in polymer structures and performance by scanning electron microscope (SEM), Fourier transform infrared absorption (FT-IR), and mercury analyzer (MA). Finally, both MIPs were used as selective sorbents for solid phase extraction (SPE) of atrazine from lake water, followed by high performance liquid chromatography (HPLC) analysis. Compared with commercial C₁₈ SPE sorbent (86.4%–94.8%), higher recoveries of atrazine in spiked lake water were obtained in the range of 90.1%–97.1% and 94.4%–101.9%, for both MIPs, respectively.     

Microwave-Assisted Extraction and Solid-Phase Separation of Quercetin from Solid Onion (Allium cepa L.)

The challenge of extraction of natural product in the twenty-first century is to achieve 100% selectivity of the desired product and develop renewable energy based processes. An object of the present work is to provide a method for producing specific bioactive compounds from agricultural products. A simple protocol was used to obtain the conditions of microwave-assisted extraction (MWAE) and ultrasound-assisted extraction (USAE). Total quercetin content under microwave irradiation for 150 sec at pH 6.25 (209 mg/ 100 gm F. wt). The effects of operating conditions, such as extraction time and pH on the extraction yield of quercetin were studied. Microwave-assisted ionic liquid-based silica sorbent (ILSis) was developed by a process involving surface chemical modification of commercial silica using a synthesized ionic liquid and characterized by FTIR. The obtained particles were successfully used as a special sorbent in a solid-phase separation process to isolate quercetin and its glycosides from solid onion. Different washing and elution solvents, such as water, water/methanol (v/v), and pure methanol were evaluated. Ionic liquid-based silica sorbent was compared with traditional C18 sorbent and it exhibited higher selectivity. The target compounds in solid onion containing quercetin and its glycosides were determined.     

茶叶中咖啡碱的微波辅助萃取研究

研究了茶叶中料液质量比、浸提温度、浸提时间、提取液pH值、微波功率、微波作用时间等因素对咖啡碱溶出效果的影响,通过正交实验,对微波辅助萃取茶叶中咖啡碱的工艺条件进行了研究。结果表明：料液质量比1：30,浸提温度90℃,浸提时间30min,提取液pH值为6,微波功率350W,微波作用20s,茶叶中咖啡碱的浸出率可达3．90％以上。     

The determination of optical brighteners in laundry detergents by reverse phase and ion pair high performance liquid chromatography

Eleven optical brighteners have been qualitatively and quantitatively determined using C₁₈, C₈, or C₂ reverse phase high performance liquid chromatography (HPLC) columns. Comparable results also were obtained using radially compressed reverse phase HPLC cartridges. Mobile phases consist of acetonitrile and methanol in water with 0.05 M phosphate buffer. Quaternary ammonium salts also are added to the mobile phase for ion pair formation. Ultraviolet (UV) detection at 340 nm gives more than adequate sensitivity for brighteners formulated between 0.05 and 2.0%. Sample preparation is simple and all components can be eluted within 15 min. Powdered and liquid detergents, fabric softeners, and bleach boosters have been routinely analyzed and results closely agree with those obtained using thin layer chromatography and densitometry.     

Synthesis and application of a molecularly imprinted polymer as a filter to reduce polycyclic aromatic hydrocarbon levels in mainstream cigarette smoke

The design and fabrication of novel filter is a promising approach to realize the reduction of harmful substance in mainstream cigarette smoke. In our work, a kind of pyrene (PYR) imprinted polymer as a part of improved filter has been successfully synthesized for the determination of polycyclic aromatic hydrocarbons (PAHs) in mainstream cigarette smoke. The molecularly imprinted polymers (MIPs) showed an good affinity towards PYR with binding capacity (Q_max) of 18.33 mg/g. Accordingly, the MIPs were used as a solid phase extraction (SPE) sorbent for the extraction and enrichment of PAHs in mixed samples to evaluate the selectivity about the MIPs. When the cellulose acetate (CA)-filter was replaced by a MIPs-filter, the amount of PAHs in the mainstream smoke was reduced by 63.6%. The application will provide technical support for the design of functional filters to reduce the harms brought by cigarette suction.     

水在超临界CO2脱除绿茶中咖啡因的作用研究

采用不同的茶叶预处理方式,并在不同的萃取条件下,用超临界CO2对茶叶进行脱除咖啡因试验,以考察茶叶含水量与咖啡因萃取率的关系。指出了水对咖啡因萃取的3方面影响,即脱附茶叶基质上的咖啡因、使茶叶膨胀而改善咖啡因的传质状况及抑制咖啡因从水相进入超临界流体相。同时说明了此3者对萃取过程的影响机理。     

Separation of perillyl alcohol from Korean orange peel by solvent extraction and chromatography

Perillyl alcohol, abundant mainly in oranges, has chemotherapeutic activity against carcinogenesis. The peel of Korean oranges was extracted by methanol, and the extract was partitioned by methanol-extract/water/chloroform, (20/5/30 vol%). To concentrate perillyl alcohol of the water-phase in the previous partition step, a glass column (2.5 i.d. x 15 cm) with reversed-phase C₁₈ packings (40–63 μm) was used. Finally, to obtain perillyl alcohol in a pure form, reversed-phase high-performance liquid chromatography (RP-HPLC) was applied. Mobile phases used were water, methanol, and acetonitrile. The flow rate of the mobile phase was 1 ml/min and UV wavelength was fixed at 205 nm. The resolution of perillyl alcohol from Korean orange peel was achieved on a μ-Bondapak C₁₈ column (3.9x300 mm, 10 μm) and in-house Chromatographic column packed with 15 μm C₁₈ preparative packings. From the experimental results, the mobile phase composition was water/acetonitrile, (65/35 vol%) and the retention time of perillyl alcohol was 20.5 min in the analytical μ-Bondapak column. The effect of injection volumes was investigated in the preparative column.     

Precipitation polymerization of molecularly imprinted polymers for recognition of melamine molecule

Molecular imprinted polymer microspheres (MIPs) were prepared by precipitation polymerization using melamine as template molecule, methacrylic acid (MAA) as functional monomer, trimethylol‐propane trimethacrylate (TRIM) as crosslinking agent, acetonitrile as solvent and dispersion medium. Release of the template was performed by continuous extraction with methanol containing 10% acetic acid. The microspheres were observed by scanning electron microscopy (SEM). The perfect microspheres were produced when the addition of crosslinker was 7.48 mmol. The binding capacity of MIPs was examined, Q_max = 68.36 μmol g^?1, and the dissociation constant at binding site of MIPs, K_d = 0.761, was estimated. Compared with the performance of conventional imprinted polymer, the imprinted microspheres showed high selectivity in special binding to template molecule. The imprinted microspheres could be used as the stationary phase in HPLC or SPE for selective extraction of melamine in daily products. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Grafting of molecularly imprinted polymers from the surface of Fe3O4 nanoparticles containing double bond via suspension polymerization in aqueous environment: A selective sorbent for theophylline

Molecularly imprinted polymers (MIPs) were grafted from the surface of Fe₃O₄ nanoparticles containing double bond via suspension polymerization in aqueous environment, and the leakage of Fe₃O₄ nanoparticles from MIPs was overcome in this study. The effect of different cross‐linker on adsorption capacity of the resultant magnetic MIPs was investigated using pure trimethylolpropane trimethacrylate (TRIM) or the mixture of TRIM and divinylbenzene (DVB) as cross‐linker. Both magnetic MIPs exhibited higher adsorption capacity for the template theophylline than the corresponding non‐imprinted polymer, and Freundlich model fitted reasonably well for theophylline adsorption on both magnetic MIPs. In addition, both magnetic MIPs exhibited good recognition properties for the template theophylline versus caffeine, and the selectivity of magnetic MIPs using pure TRIM as cross‐linker (mag‐MIP‐TRIM) was much higher than those using the mixture of TRIM and DVB as cross‐linker (mag‐MIP‐TRIM and DVB). The adsorption dynamics of theophylline on both magnetic MIPs fitted well with the first‐order kinetic model, but the adsorption equilibrium on mag‐MIP‐TRIM and DVB reached faster than that on mag‐MIP‐TRIM. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Two-step chromatographic procedure for the preparative separation and purification of epigallocatechin gallate from green tea extracts

The preparative separation and purification of epigallocatechin gallate (EGCG) from green tea extracts was achieved by a two-step chromatographic procedure. In the first step, a preparative β-cyclodextrin (β-CD) bonded silica chromatography operated in the polar organic mode using methanol/acetonitrile/acetic acid as the mobile phase was applied. Due to a high selectivity for EGCG over epicatechin (EC) and caffeine (CA), an efficient separation of EGCG from EC and CA was achieved and the system could be scaled-up with high recovery of EGCG (>90%). The EGCG-rich fraction obtained from the first step was subjected to the second step where a preparative C-18 chromatography operated in the reversed-phase mode using water/methanol/acetic acid as the mobile phase was applied. The resolution of EGCG was significantly enhanced as the sample contained no EC and CA. The system could also be scaled-up and both the purity and recovery of EGCG reached about 90%. In summary, the chromatographic procedure consisting of two such complementary steps gave a satisfactory purification results: the purity and recovery of EGCG were >90% and >80%, respectively. Most significantly, the purification method could be more easily scaled-up, showing good potential for industrial applications.     

HPLC analysis of desmosterol, 7-dehydrocholesterol,and cholesterol

A simple and sensitive method to analyzed mixtures of desmosterol, 7-dehydrocholesterol and cholesterol is described. The method involves the oxidative conversion of the sterols with cholesterol oxidase, followed by high performance liquid chromatographic (HPLC) analysis. A C₁₈ reversed phase column (3 μm, 75×4.6 mm) and a mixture of methanol and acetonitrile (1∶1, v/v) at a rate of 1 ml/min are used to separate the sterols. The eluted sterols are quantified by measuring UV absoprtion at 240 nm. As little as 10 pmoles of sterol can be quantified under these conditions.     

Cloud Point Extraction (CPE) of Parabens using Nonionic Surfactant Phase Separation

A cloud point extraction (CPE) method was developed using silicone-ethylene oxide surfactant, DC193C, to study the equilibrium phase separation of parabens in environmental water samples. The volume of the surfactant rich phase (V_s), aqueous phase (V_w), preconcentration factor (C_F), distribution coefficient (K_d), and percentage of recovery (%R) were evaluated to obtain the optimum condition for phase separation of parabens. Satisfactory results were obtained whereby the preconcentration factor for methylparaben, ethylparaben, propylparaben, and benzylparaben were close to 65, 60, 80, and 45, respectively, at 0.5% weight of surfactant. The presence of DC193C gave a low phase volume ratio but insignificant result was observed with the increased of surfactant concentration. The parabens were well separated on a reverse-phase Chromolith C₁₈ column (100 mm × 4.6 mm) with a gradient elution (acetonitrile: water; 30:70 v/v) and detected at 254 nm. The proposed method was successfully applied to environmental samples such as river water, treated wastewater, sea water, and tap water with satisfactory results. The method detection limit was 0.1–0.2 ppb and the recoveries were 71.2–97.7% with the relative standard deviations of 0.3–2.1%.     

Molecularly imprinted monolithic material for the extraction of three organic acids from Salicornia herbacea L

A molecularly imprinted monolithic material was designed and prepared by in situ thermally initiated copolymerization for the extraction of protocatechuic acid, caffeic acid, and ferulic acid from Salicornia herbacea L. Field emission scanning electron microscopy and offline solid‐phase extraction (SPE) were investigated for the characterization of this material. The extract samples were loaded onto and passed through the monolithic material; the target compounds were selectively retained on the material, whereas other interfering substances were quickly washed out. Chromatographic analysis was conducted on a C₁₈ column with ultraviolet detection at 270 nm, and an eluting solution consisting of acetonitrile, water, and acetic acid (14/86/0.5 v/v/v, pH 5.0) was used as the mobile phase at a flow rate of 0.8 mL/min. The linearity was confirmed in the concentration ranges of 0.10–200.00, 0.20–400.00, and 0.30–600.00 μg/mL for protocatechuic acid, caffeic acid, and ferulic acid, respectively, with r² greater than 0.9997. The SPE recoveries of the three organic acids ranged from 71.08 to 81.02%, and the coefficient of variation (precision) was 3.08–5.70%. This method is simple, economical, and specific and has been used successfully in the extraction of three organic acids from S. herbacea L. This cartridge can be used as a potential tool for the extraction of drugs from natural plants. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Selective solid‐phase extraction of naphazoline using imprinted polymers as matrix prepared by precipitation polymerization

The molecularly imprinted polymers (MIP) for drug naphazoline (NAZ) have been synthesized by precipitation polymerization. The effect of the dispersive solvents dichloromethane (DCM), acetonitrile (ACN), and Methanol (MeOH) on particle size and morphology of MIP (P1, P2, and P3) was investigated by scanning electron microscopy (SEM). The selectivity of P1, compared with nonimprinted polymer (NIP), C₈ and C₁₈ were evaluated via static adsorption using UV spectrophotometer. The result showed that the bond amount of P1 for NAZ was significantly higher than other sorbents. The P1 were applied as a solid‐phase extraction (SPE) stationary phase to extract the NAZ from nasal drops and recoveries of more than 89% (relative standard deviations, RSD <5%) were obtained by high performance liquid chromatograph (HPLC) analyses. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation of (S)‐ibuprofen‐imprinted polymer and its molecular recognition study

Two molecularly imprinted polymers (MIPs) were prepared using (S)‐ibuprofen as the template molecule as well as methacrylic acid (MAA) or 4‐vinylpyridine and ethylene glycol dimethacrylate (EGDMA) as the functional monomer and crosslinker, respectively. Free radical polymerization was carried out at 4°C under ultraviolet (UV) radiation. The MIPs thus obtained were ground into 25–44 μm, which were slurry packed into analytical columns. The template molecules were removed by acetic acid/methanol solution (1:9, v/v). high‐performance liquid chromatography (HPLC), with UV detection, was used to evaluate the binding performance of the MIP for the template. The selectivity of (S)‐ibuprofen and naproxen on the host–guest system were assessed using acetonitrile‐based mobile phases. The limits of detection of ibuprofen and naproxen were found to be 0.1844 mmol/L and 0.3264 mmol/L, while the limits of quantitation were 0.6262 mmol/L and 1.0909 mmol/L, respectively. The stationary phase was applied successfully to the commercial tablet analysis. Ibuprofen and naproxen were extracted from tablets with acetonitrile; analysis results showed a good relative standard deviation (RSD) of 0.81–1.24% and accuracy from ?4.01 to +2.98% for ibuprofen as well as an RSD of 0.59–0.86% and accuracy from ?4.01 to ?2.01% for naproxen. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2972–2979, 2006     

3,3′‐Diindolylmethane imprinted polymers: synthesis,characterization and analytical procedure for template isolation from biological matrix

A novel sorbent for the separation of 3,3′‐diindolylmethane (DIM) has been developed. DIM was used as a template molecule to prepare twelve imprinted polymers from seven different functional monomers in six various porogens in the presence of ethylene glycol dimethacrylate as a crosslinker. The binding capacity showed that the highest binding specificity was achieved when allylamine as the monomer and carbon tetrachloride as the porogen were used to form bulk polymers. Binding capacities were 130.4 ± 2.8 µg g^?1 for imprinted MIP7_a polymer versus 49.03 ± 0.44 µg g^?1 for non‐imprinted NIP7_a polymer. An imprinting factor of 3.12 reflected the high specificity of MIP7_a. A solid‐phase extraction protocol was fully optimized. Two methanol–water systems were selected as the most effective for loading and washing steps, while acetonitrile was chosen as the most efficient eluent suitable for recovery of 91.7 ± 3.8% of DIM. Optimal concentration of DIM and volume of loaded sample were also examined. A loaded volume of 2.5 mL was the most appropriate for 0.625 and 1.25 mg L^?1. The use of MIP7_a for the separations of DIM from spiked bovine serum albumin was evaluated, showing a total recovery of 87.7 ± 3.5%. The commercial sorbent C18 was not suitable for such an application. © 2013 Society of Chemical Industry     

Effect of Mobile Phase Additives on the Resolution of Four Bioactive Compounds by RP-HPLC

The use of mobile phase additives enhances the separation and resolution of the bioactive compounds on the C₁₈ column. Chlorogenic acid, caffeic acid, rutin, and scoparone from Herba Artemisiae Scopariae were investigated as the target compounds. Acetic acid, triethylamine, inorganic salts, and several ionic liquids were added as mobile phase additives into methanol/water (40:60, v/v). The result revealed that a mobile phase with 0.01 mol/L of ionic liquid [BMIM][BF₄] enabled the optimum separation of the four target compounds.     

Molecularly imprinted polymers for the selective recognition of l‐phenylalanine based on 1‐buty‐3‐methylimidazolium ionic liquid

To enhance the affinity of 4‐vinyl pyridine to l ‐phenylalanine (l ‐Phe) and convert the imprinting process from the aqueous phase to the organic phase, an oil‐soluble amino acid ionic liquid was introduced as a template. In this study, 1‐butyl‐3‐methylimidazolium α‐aminohydrocinnamic acid salt was first applied to prepared surface molecularly imprinted polymers (MIPs) in acetonitrile for the selective recognition of l ‐Phe. Fluorescence quenching analysis of the functional monomer on the template was investigated under different conditions to study the imprinting mechanism. Several binding studies, such as the sorption kinetics, sorption thermodynamics, and solid‐phase extraction application, and the chiral resolution of racemic phenylalanine were investigated. The binding isotherms were fitted by nonlinear regression to the Freundlich model to investigate the recognition mechanism. The affinity distribution analysis revealed that polymers imprinted by ionic liquid showed higher homogeneous binding sites than those imprinted by l ‐Phe. The competition tests were conducted by a molecularly imprinting solid‐phase extraction procedure to estimate the selective separation properties of the MIPs for l ‐Phe. The target MIP was shown to be successfully for the separation of l ‐Phe from an amino acid mixture. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42485.     

Separation and quantitative determination of monoacylglycerol mixtures by reversed phase HPLC

The separation and quantitative determination of underivatized saturated and unsaturated monoacylglycerol were examined by reversed phase high performance liquid chromatography using acetonitrile/water as the mobile phase. Monoacylglycerol (MG) mixtures containing saturated MG (C₆-MG-C₁₈-MG), monooleoylglycerol and monolinoleoylglycerol were sufficiently resolved, but mixtures of 1-MG and 2-MG with the same acyl group could not be separated under the conditions given below: column, C-8 chemical bonded column (4.6 × 250 mm); sample solvent, diethyl ether (UV detector at 210–215 nm) or chloroform; mobile phase, acetonitrile/water (7:3, v/v). Quantitative determinations were made for mixtures of three components (representative standard MGs) on a reversed phase column (Unisil Q, C-8) using a UV detector and the internal standard method. Standard deviation and coefficient of variation gave accurate, reproducible results.