Hollow Fiber Liquid-phase Microextraction Research Articles

Determination of phthalic acid esters in water samples by hollow fiber liquid-phase microextraction prior to gas chromatography tandem mass spectrometry

A new hollow fiber liquid-phase microextraction (HF-LPME) method has been developed for the extraction of a group of phthalic acid esters (PAEs) of interest from different water samples prior to gas chromatography tandem mass spectrometry analysis. HF-LPME was carried out using 1-octanol as extraction solvent followed by a back extraction step with cyclohexane. The different parameters that affect HF-LPME such as sample pH, ionic strength, extraction time, stirring rate, extraction temperature and back extraction conditions were investigated. The optimized conditions involved the extraction of 10 mL of sample without pH adjustment or addition of salt during 75 min under a stirring of 850 rpm at 60 °C and subsequent desorption with 200 μL of cyclohexane for 10 min in an ultrasonic bath. The method was validated in terms of calibration and recovery studies using dibutyl phthalate-d4 as internal standard. The developed procedure gave satisfactory recovery (74–120%) and relative standard deviation values (<20%) for the studied PAEs in mineral, tap, pond and waste water samples.

Multi-elemental ionic liquid-based solvent bar micro-extraction of priority and emerging trace metallic pollutants (Cd, Ag, Pd) in natural waters.

Transition metals Cd, Pd and Ag are toxic even at very low concentration. Cd is considered a priority substance; while, Pd and Ag are emerging pollutants. Membrane technologies have been applied for their extraction; however, they require important amounts of reagents, time and energy. Additionally, effective reagents for metal extraction in saline natural waters are limited. In this case, hollow fiber liquid phase micro-extraction with a configuration of solvent bar (SBME) using the ionic liquid Cyphos® 101 as extractant is proposed. Optimized conditions for SBME of Cd, Ag and Pd were 50% Cyphos® 101 in the organic solution, extraction time 30 min and 800 rpm stirring rate. Leaching was in all cases lower than 0.1%. Metallic concentrations were measured by flame atomic absorption spectroscopy. The method was applied to the extraction of Ag, Cd and Pd in natural water samples. Except for waste water, Pd extraction was higher than 90% in all cases. Cd (≈100%) and Ag (93-95%) offered their best results for saline samples. Concluding, the proposed system is a low cost and green methodology that allows a simple and fast extraction of trace pollutants such as Ag, Cd and Pd in different natural waters, including highly saline samples.

In situ derivatization and hollow-fiber liquid-phase microextraction to determine sulfonamides in water using UHPLC with fluorescence detection.

A sensitive method for determining sulfonamides in water was developed and validated through in situ derivatization and hollow-fiber liquid-phase microextraction with ultra-high performance liquid chromatography and fluorescence detection. The target sulfonamides were sulfadiazine, sulfacetamide, sulfamerazine, sulfamethazine, sulfamethoxypyridazine, sulfachloropyridazine, sulfamethoxazole, and sulfisoxazole. Following in situ derivatization with fluorescamine, three-phase hollow-fiber liquid-phase microextraction with an S 6/2 polypropylene hollow-fiber membrane was applied automatically using a multipurpose autosampler. Experimental parameters including derivatization time, choice of organic phase, pH of donor and acceptor phase, stirring rate, extraction temperature and time were optimized. Under optimized conditions, the target sulfonamides achieved excellent linearity with correlation coefficients of 0.9924-0.9994 within the concentration range of 0.05-5μg/L. The limits of detection of the eight sulfonamides were 3.1-11.2ng/L, and the limits of quantification were 10.3-37.3ng/L. Enrichment factors of 0.1 and 5μg/L sulfonamides spiked in lake water were 14-60, and recoveries were 56-113% with relative standard derivations of 3-19%. Applied with the developed method, sulfamerazine and sulfamethoxazole were measurable in both influent and effluent water of the three sewage treatment plants in Guangzhou, China. The developed method was sensitive and provided an alternative method for simultaneously enriching and quantifying multiple sulfonamides in environmental water.

Application of membrane technology in the treatment and analysis of triazine pesticides in water

The quality of consumable water is decreasing due to increasing water pollution caused by the production and use of human-made chemicals. A significant part of these chemicals are pesticides from the class of triazines since they are widely used in agriculture as herbicides. Water treatment techniques mainly rely on separation science, where the membrane technology has been identified as the most useful. Membrane processes used in water treatment are microfiltration, ultrafiltration, nanofiltration and reverse osmosis. In general, the pollutant retention/rejection by membranes depends on the physicochemical properties of the membrane i.e. membrane material, porosity, pore size and on the properties of the pollutant molecule i.e. size, length, width, molecular weight, hydrophobicity or dipole moment. The pollutant retention also depends on the feed-water composition (organic matter and salt presence, solute concentration, water pH). Thus, effective water treatment depends on the selection of an appropriate type of membrane for a particular type of pollutants. Membrane technology is also significant because it is used in polluted water analysis, more precise as a part of a liquid-phase or solid-phase microextraction. Among several developed membrane-based microextraction methods, in triazine polluted water analysis common are membrane-protected solid-phase microextraction and hollow-fiber liquid-phase microextraction. In this field, researchers tend to achieve membrane-pollutant compatibility through the synthesis of polymeric materials with molecular recognition properties i.e. through a technology called molecular imprinting.

Determination of blood concentrations of main active compounds in Zi-Cao-Cheng-Qi decoction and their total plasma protein binding rates based on hollow fiber liquid phase microextraction coupled with high performance liquid chromatography.

Oil-in-salt hollow fiber liquid phase microextraction coupled with high performance liquid chromatography ultraviolet detection (HPLC-UV) was developed for determination of the blood concentrations of the main active compounds, hesperidin, honokiol, shikonin, magnolol, emodin and β,β'-dimethylacrylshikonin, after oral administration of Zi-Cao-Cheng-Qi decoction (ZCCQD) and their total plasma protein binding rates. In the procedure, a hollow fiber segment was immersed in organic solvent to fill the solvent in the fiber lumen and wall pore, and then the fiber was immersed into sodium chloride solution to cover a thin salt membrane on the fiber wall pore filling organic solvent. Various factors affecting the procedure, such as extraction solvent, sample phase pH, stirring rate, extraction time, NaCl concentration and fiber immersion time in the NaCl solution, were optimized. Under the optimum conditions, good linearities (r2≥0.9905), low limits of detection (0.7-2.5ng/mL) or quantitation (1.2-12ng/mL), satisfactory precision (2.6%-12.8%) and accuracy (81.0%-114.2%) of this method, were observed. The results showed that, after oral administration of a 25g/kg dose, (1) the blood concentrations (at 0.5h) of hesperidin, honokiol, shikonin, magnolol, emodin and β,β'-dimethylacrylshikonin were 0.45, 0.40, 0.48, 0.74, 0.11 and 1.11μg/mL, respectively; (2) the total plasma protein binding rates of the six active compounds were 42.0% (hesperidin), 71.8% (honokiol), 64.6% (shikonin), 77.7% (magnolol), 75.3% (emodin) and 75.7% (β,β'-dimethylacrylshikonin), respectively. The proposed procedure coupled with HPLC shows obvious advantages, such as low solvent consumption, simple operation, high sensitivity and strong purifying and can be used for the determination of both the blood concentrations and total plasma protein binding rates of active compounds in traditional Chinese medicine.

Ion‐pair‐based hollow‐fiber liquid‐phase microextraction combined with high‐performance liquid chromatography for the simultaneous determination of urinary benzene, toluene, and styrene metabolites

In the current study, a novel technique for extraction and determination of trans,trans-muconic acid, hippuric acid, and mandelic acid was developed by means of ion-pair-based hollow fiber liquid-phase microextraction in the three-phase mode. Important factors affecting the extraction efficiency of the method were investigated and optimized. These metabolites were extracted from 10mL of the source phase into a supported liquid membrane containing 1-octanol and 10%w/v of Aliquat 336 as the ionic carrier followed by high-performance liquid chromatography analysis. The organic phase immobilized in the pores of a hollow fiber was back-extracted into 24μL of a solution containing 3.0mol/L sodium chloride placed inside the lumen of the fiber. A very high preconcentration of 212- to 440-fold, limit of detection of 0.1-7μg/L, and relative recovery of 87-95% were obtained under the optimized conditions of this method. Therelative standard deviation values for within-day and between-day precisions were calculated at 2.9-8.5 and 4.3-11.2%, respectively. The method was successfully applied to urine samples from volunteers at different work environments. The results demonstrated that the method can be used as a sensitive and effective technique for the determination of the metabolites in urine.

Effects of barley variety, dietary fiber and β-glucan content on bile acid composition in cecum of rats fed low- and high-fat diets

Diet-induced obesity and insulin resistance have been linked to changes in bile acid (BA) profiles, which in turn are highly dependent on the dietary composition and activity of the gut microbiota. The objective of the present study was to investigate whether the type and level of fiber had an effect on cecal BA composition when included in low- and high-fat diets. Groups of rats were fed two barley varieties, which resulted in three test diets containing three levels of β-glucans and two levels of dietary fiber. BAs were preconcentrated using hollow fiber liquid-phase microextraction and quantified by gas chromatography. The amount of the secondary BAs, lithocholic-, deoxycholic- and hyodexycholic acids was generally higher in groups fed high-fat diets compared with corresponding acids in groups fed low-fat diets (P<.05). In contrast, most of the primary and the secondary BAs, ursodeoxycholic acid and β- and ω-muricholic acids, were two to five times higher (P<.05) in groups fed low-fat diets than in groups fed high-fat diets. This was particularly true for groups fed the highest level of β-glucans and in some cases also the medium level. The BA profile in the gut was strongly dependent on the amount and type of dietary fiber in the diet, which may be useful in the prevention/treatment of diseases associated with changes in BA profiles.

Novel generation of deep eutectic solvent as an acceptor phase in three-phase hollow fiber liquid phase microextraction for extraction and preconcentration of steroidal hormones from biological fluids

In this study, a novel generation of deep eutectic solvents (DESs) was used as an acceptor phase in three-phase hollow fiber liquid phase microextraction (HF-LPME) based on two immiscible organic phases. It was compared with other common DESs for extraction and preconcentration of dydrogesterone (DYD) and cyproterone acetate (CPA) from urine and plasma samples. The extracted analytes were analyzed by high performance liquid chromatography with UV–vis detector (HPLC-UV). This phosphonium based DES due to low volatility, low price and multifunctionality introduced itself as worthy next generation of acceptor phase in HF-LPME. The factors affected on extraction efficiency of the analytes were investigated and optimized. The performance of the proposed method was studied in terms of linear ranges (LRs from 1 to 500µgL−1 with R2 ≥ 0.9946), precision (RSD% ≤ 6.3) and limits of detection (LODs in the range of 0.5–2µgL−1). Under the optimized conditions, preconcentration factors in the range of 187–428 were obtained. Finally, the method was applied to the analysis of DYD and CPA in human urine and plasma samples and desirable results were obtained.

Optimization of multiwalled carbon nanotubes reinforced hollow-fiber solid-liquid-phase microextraction for the determination of polycyclic aromatic hydrocarbons in environmental water samples using experimental design.

A novel design of hollow-fiber liquid-phase microextraction containing multiwalled carbon nanotubes as a solid sorbent, which is immobilized in the pore and lumen of hollow fiber by the sol-gel technique, was developed for the pre-concentration and determination of polycyclic aromatic hydrocarbons in environmental water samples. The proposed method utilized both solid- and liquid-phase microextraction media. Parameters that affect the extraction of polycyclic aromatic hydrocarbons were optimized in two successive steps as follows. Firstly, a methodology based on a quarter factorial design was used to choose the significant variables. Then, these significant factors were optimized utilizing central composite design. Under the optimized condition (extraction time=25min, amount of multiwalled carbon nanotubes=78mg, sample volume=8mL, and desorption time=5min), the calibration curves showed high linearity (R2 =0.99) in the range of 0.01-500ng/mL and the limits of detection were in the range of 0.007-1.47ng/mL. The obtained extraction recoveries for 10ng/mL of polycyclic aromatic hydrocarbons standard solution were in the range of 85-92%. Replicating the experiment under these conditions five times gave relative standard deviations lower than 6%. Finally, the method was successfully applied for pre-concentration and determination of polycyclic aromatic hydrocarbons in environmental water samples.

Methods of liquid phase microextraction for the determination of cadmium in environmental samples

Liquid phase microextraction (LPME) has been widely used in extraction and preconcentration systems as an excellent alternative to conventional liquid phase extraction. In this work, a critical review is presented on liquid phase microextraction techniques used in the determination of cadmium in environmental samples. LPME techniques are classified into three main groups: single-drop liquid phase microextraction (SDME), hollow fiber liquid phase microextraction (HF-LPME), and dispersive liquid-liquid microextraction (DLLME). Methods involving these liquid phase microextraction techniques are described, addressing advantages and disadvantages, samples, figures of merit, and trends.

Development of an on-line microextraction method for use in fiber-spray/mass spectrometry

A novel fiber-spray/mass spectrometry method using a piece of a porous hollow fiber is described. An adapter, fabricated by a 3D-printer, was designed to connect the fiber and a standard ESI (electrospray ionization) needle, in which a Taylor cone was formed and the resulting ions were detected by a mass spectrometer. Since a porous hollow fiber is usually used for microextraction, the so-called hollow fiber liquid-phase microextraction (HF-LPME) method, a new methodology that involves coupling HF-LPME and fiber-spray, was developed for the first time. We report herein on the design and testing of a microextraction kit. The kit consists of a centrifuge tube (reservoir for the sample solution) and a piece of a porous hollow fiber (for sample extraction). The kit was placed between the mass inlet and the ESI needle. Using the kit, analytes can be extracted from a very dilute solution and then evaporate and escape from the fiber surface. When they make contact with the ESI plume, which arises from the ESI needle tip, the molecules are ionized and then detected by a mass spectrometer. Using the setup, it was possible to improve the limit of detection after microextraction by ∼360-fold when 3,4-MDMA (3,4-methylenedioxymethamphetamine) was analyzed, and the limit of detection achieved was 2ng/mL.

Study of Anti-Renal Cancer Ingredients in Scutellaria barbata on Hollow Fibre Cell Fishing and Hollow Fibre Liquid Phase Microextraction

Study of Anti-Renal Cancer Ingredients in Scutellaria barbata on Hollow Fibre Cell Fishing and Hollow Fibre Liquid Phase Microextraction

Two-phase hollow fiber-liquid microextraction based on reverse micelle for the determination of quercetin in human plasma and vegetables samples

A new two-phase hollow fiber-liquid microextraction based on reverse micelle as sensitive and efficient method for the extraction of quercetin in human plasma, onion and tomato samples was developed for the first time. The extraction is based on the solubilization of analyte in the aqueous core of the reverse micelle of cationic cethyltrimethyl ammonium bromide surfactant, CTAB, which are present in the organic phase and are used as acceptor phase in hollow fiber-liquid phase microextraction. Experimental results show that the electrostatic interaction between the oppositely charged surfactant head group present in the reverse micelles and the analyte molecule has a key role in the extraction. Extraction parameters including the organic phase, pH, surfactant concentrations, stirring rate, extraction time, temperature and ionic strength were optimized. The optimum condition is obtained when the variables are set to: pH= 7.5, organic solvent= 1-octanol, CTAB concentration= 7mmolL−1, stirring rate= 900rpm at room temperature and extraction time= 30min. Under the mentioned condition, the calibration range was found to be linear over 0.5–1000ngmL−1 with the limit of detection of 0.1ngmL−1. The extraction recovery of 97.4%, with relative standard deviation of 3.5%, was obtained via tree replicated measurements on a 15ngL−1 quercetin standard solution. Finally, the newly developed method was successfully used for the preconcentration and determination of quercetin in plasma, onion and tomato samples.

Salicylic acid determination in estuarine and riverine waters using hollow fiber liquid-phase microextraction and capillary zone electrophoresis.

A low-cost methodology using hollow fiber liquid-phase microextraction (HF-LPME) and capillary zone electrophoresis (CZE) with UV-Vis detector was developed to analyze the salicylic acid (SA) in estuarine and riverine waters. The technique is easy-to-use and rapid, and demands little volume of organic solvent. The extraction was carried out using a polypropylene membrane supporting into octan-1-ol. HF-LPME under optimized conditions (donor solution sample pH 2, acceptor solution pH 14, sample volume 25mL, fiber length 10cm, acceptor volume 25μL, extraction time 3h and stirring speed 350rpm) presented high enrichment factor (407 times) and good recovery in real water samples (from 88 to 110%). A limit of detection of 2.6μgL-1 was achieved using CZE with UV-Vis detector as quantification method. The method was applied to direct quantification of SA in environmental complex estuarine and riverine water matrices.

Speciation of Arsenic(III) and Arsenic(V) based on Triton X-100 hollow fiber liquid phase microextraction coupled with flame atomic absorption spectrometry

ABSTRACTA novel method based on Triton X-100 of hollow fiber liquid phase microextraction coupled with flame atomic absorption spectrometry has been developed for the speciation of Arsenic(III) and Arsenic(V). Triton X-100 was used as an extractant and an acceptor solution. Under optimized conditions, a detection limit of 0.08 ng mL−1 for Arsenic(III) and an enrichment factor of 280 were achieved. The relative standard deviation for five replicate determinations of 10 ng mL−1 Arsenic(III) was 5.2%. The proposed method was successfully applied to the speciation of Arsenic(III) and Arsenic(V) in environmental and biological samples with satisfactory results.

Solvent bar micro-extraction (SBME) based determination of PAHs in seawater samples

Measuring the impact of PAHs in seawater samples is often difficult due to the low concentrations in which they appear and the complexity of the sample matrix. Traditional methods for sample preparation such as liquid-liquid extraction and solid phase extraction require the use of excessive amounts of solvents and reagents, and sample handling. In this work, hollow fiber liquid phase micro-extraction (HFLPME), in the configuration of solvent bar micro-extraction (SBME), was proposed as an environmentally friendly and more effective tool, for the extraction of the 16 priority PAHs from seawater samples. Extraction was conducted using hexane as a solvent. Enrichment factors from 45 to 163 were obtained after 60min at a stirring rate of 500rpm in the sample. Moreover, a negative linear relationship was observed between the enrichment factor and the molecular weight of the PAHs. Under optimized conditions, the limits of detection were in the range from 0.21 to 0.82ngL−1, the method showed a linear response up to 500μgL−1, and the average relative standard deviation for seawater samples spiked with 5ngL−1 was 11.6%. After calibration, the SBME was applied to extract PAHs in seawater samples from the Bay of Cadiz (SW Spain), showing an average recovery of 99%. In conclusion, the SBME is an environmentally friendly, one-step alternative for sample preparation in the determination of PAHs in seawater samples.

Hollow fiber based liquidp hase microextraction combined with high-performance liquid chromatography for study of the pharmacokineticsof berberine in rat plasma

Objective A new hollow fiber liquid phase microextraction combined with high-performance liquid chromatography was developed to determine the concentration of berberine in rat plasma. Methods Parameters that affect the hollow fiber liquid phase microextraction processes were investigated and optimized. The optimized conditions were pH of donor and acceptor phases 12 and 2.0, respectively; extraction time 20 min; stirring speed 800 rpm; and addition of 10 % (w/v) salt. Under the optimized conditions, the preconcentration factor for berberine was 347. Moreover, a rapid and sensitive method was developed to determine berberine in rat plasma by HPLC. Results The calibration curve for berberine was linear in the range of 10-1000 ng/ml (r2≥0.9992). The limit of quantitation for the analyte was 10 ng/ml (S/N=10). The limit of detection for the analyte was 3.3 ng/ml (S/N=3). The intra-day and inter-day precision, and stability (RSD) were less than 6.3%. The average recovery was 96.7% ± 3.82%, and RSD was 4.82%. Conclusions The method is efficient, green, accurate and repeatable. It can be applied in determination of berberine in rat plasma. Key words: Berberine; Hollowfiber liquid phase microextraction; Chromatography, high pressure liquid

Hollow-fiber liquid-phase microextraction based on carrier-mediated transport for determination of urinary methyl hippuric acids

ABSTRACTHollow-fiber liquid-phase microextraction based on carrier-mediated transport for analysis of methyl hippuric acids in aqueous samples is described. Under optimized conditions, relative recoveries of 83%–98% and limits of detection of 2–3 µg L−1 were obtained, with linear calibration curves for the three isomers in the range of 10–50,000 µg L−1. The method was applied for the determination of urine samples of volunteers at various working environments.

Hollow Fiber Supported Liquid Membrane Extraction Combined with HPLC-UV for Simultaneous Preconcentration and Determination of Urinary Hippuric Acid and Mandelic Acid

This work describes a new extraction method with hollow-fiber liquid-phase microextraction based on facilitated pH gradient transport for analyzing hippuric acid and mandelic acid in aqueous samples. The factors affecting the metabolites extraction were optimized as follows: the volume of sample solution was 10 mL with pH 2 containing 0.5 mol·L−1 sodium chloride, liquid membrane containing 1-octanol with 20% (w/v) tributyl phosphate as the carrier, the time of extraction was 150 min, and stirring rate was 500 rpm. The organic phase immobilized in the pores of a hollow fiber was back-extracted into 24 µL of a solution containing sodium carbonate with pH 11, which was placed inside the lumen of the fiber. Under optimized conditions, the high enrichment factors of 172 and 195 folds, detection limit of 0.007 and 0.009 µg·mL−1 were obtained. The relative standard deviation (RSD) (%) values for intra- and inter-day precisions were calculated at 2.5%–8.2% and 4.1%–10.7%, respectively. The proposed method was successfully applied to the analysis of these metabolites in real urine samples. The results indicated that hollow-fiber liquid-phase microextraction (HF-LPME) based on facilitated pH gradient transport can be used as a sensitive and effective method for the determination of mandelic acid and hippuric acid in urine specimens.

Study on Antitumour Activity of Scutellarin and Its Metabolite Scutellarein by Combining Activity Screening, Target Tissue Distribution and Pharmacokinetics

Ingredients in traditional Chinese medicine (TCM) can be absorbed into blood and reach and maintain effective concentrations in the target organ, which is the premise of the ingredients taking effect in vivo. Hollow fibre cell fishing (HFCF) based on ACHN human renal tubular cells or HepG2 hepatoma cells using high-performance liquid chromatography with ultraviolet detection (HPLC/UV), coupled with hollow fibre liquid-phase microextraction (HF-LPME) with HPLC/UV, was developed and employed for the first time to study the antitumour activity of scutellarin, a main ingredient in breviscapine, and its metabolite scutellarein after intraperitoneal injection of breviscapine. The antitumour activity of these ingredients was evaluated by combining their activity screening, target tissue distribution and pharmacokinetics (PK). Before application, the cell growth state, survival rate, binding between fibre active centre or nutrient solution and ingredients, positive and negative control and repeatability for HFCF were investigated; validations of the HF-LPME methodology were optimized and evaluated. The study found that scutellarin can be rapidly absorbed into blood and metabolize partly into scutellarein, and both can reach liver or kidney, combine with ACHN or HepG2 cells and maintain effective concentrations. Thus, scutellarin and scutellarein have potential as lead ingredients for treatment of liver or kidney tumours, and breviscapine injection may have potential properties for use in treatment or prevention of liver and kidney tumours, at least. HFCF and HF-LPME coupled with HPLC can contribute to simultaneous investigation of the antitumour activity of multiple ingredients in TCMs by combining activity screening, tissue distribution and PK studies.