Fiber Liquid Phase Microextraction Method Research Articles

Combination of online hollow fiber liquid phase microextraction with smartphone-based sensing for in situ formaldehyde assay in fabric and wastewater samples.

A miniaturized analytical methodology was introduced based on the combination of a direct and online hollow fiber microextraction method with smartphone color detection. The method was used for the determination of formaldehyde (target analyte) in fabric and wastewater samples. In this regard, two reagents including ammonium acetate buffer and acetylacetone were added to the formaldehyde samples to create a colored compound. The colored compound was extracted from the sample by using the hollow fiber liquid-phase microextraction method, the extracted phase was not taken out of the extraction box and was directly transferred into a specially designed detection cell, and a smartphone was applied forin-situ color sensing and data readout. This combination gathered the advantages of both state-of-the-art microextraction techniques and smartphone sensing. Formaldehyde, as a carcinogenic compound widely used in paint and clothing industries, was selected as a model test. Factors affecting extraction efficiency were investigated and optimized, including the type of organic solvents, reagent concentration, salt, pH, stirring speed, reaction temperature, and extraction time. The linear region of the method under optimal conditions was 40-1500µg L-1 for wastewater samples and 0.3-11.2mg kg-1 for fabrics. The limit of detection and limit of qualification were 13 and 40µg L-1, respectively. The relative standard deviations for concentrations of 100 and 1000µg L-1 were 6% and 4%, respectively. To evaluate the application of the method for real samples, types of fabric and two samples of oil refinery wastewater were selected. The relative recovery in real samples was 84-98%. The results of the analytical parameters of the method show that the developed method can be used as an efficient method to determine formaldehyde in real samples.

Development of a hollow fiber–liquid phase microextraction method using tissue culture oil for the extraction of free metoprolol from plasma samples

In this research, a method known as a hollow fiber-liquid-phase microextraction was employed to extract and concentrate free metoprolol from plasma samples. The extracted analyte was subsequently determined using high-performance liquid chromatography coupled with a diode-array detector. Several parameters, including hollow fiber length, sonication time, extraction temperature, and salt addition, were investigated and optimized to enhance extraction efficiency. After extracting the analyte under optimum conditions from plasma samples, the enrichment factor and extraction recovery were 50 and 86 %, respectively. Moreover, the method exhibited detection and quantification limits of 0.41 and 1.30 ng mL−1, respectively. The analysis of real samples demonstrated satisfactory relative recoveries in the range of 91–99 %.

Application of an improved hollow fiber liquid phase microextraction technique coupled to LC-MS/MS to studying migration of fluorescent whitening agents from plastic food contact materials

In this paper, a new hollow fiber liquid-phase microextraction method was developed to improve the extraction of five fluorescent whitening agents that migrated from plastics food contact materials. Influencing factors, such as the types of membrane, the extraction solvent, the stirring speed, the addition of salt ion, and extraction time, were investigated in detail. Under the optimal conditions, high enrichment factors (71–205) can be obtained with 15 μL extraction solvent. The new method is advantageous; the polypropylene hollow fiber membrane modified by sepiolite nanoparticles had excellent solvent binding force and mass transfer effect compared with the conventional extraction technique. The extracts were analyzed by high performance liquid chromatography–tandem mass spectrometry, the limits of detection were 0.3 or 0.9 ng kg−1 with good correlation coefficients (r 2 ≥ 0.9940) for the five fluorescent whitening agents. The intra-day and inter-day recoveries ranged between 82.6% and 112%, with a relative standard deviation of less than 12%. The established method was successfully applied to the analysis of fluorescent whitening agent migration from four types of plastic food contact materials immersed in three food simulants.

Development of Hollow Fiber Liquid Phase Microextraction Method for Determination of Diazinon Residues in Vegetable Samples

An extraction method based on a combination of hollow fiber liquid-phase microextraction with high-performance liquid chromatography diode array detector (HF-LPME HPLC-DAD) has been developed and demonstrated to analyze pesticide residues in vegetables. This study aims to determine the optimum extraction conditions and validation performance of this method. Diazinon pesticide was selected as the target model analyte. HF-LPME is performed by stacking microliter organic solvent droplets through an HPLC syringe coated with polypropylene hollow fiber by directly dipping it into the sample solution and stirring it during the extraction process. Finally, the organic solvent was put into an HPLC syringe at the end of the extraction. Then, it was injected into the HPLC-DAD at the wavelength of 247 nm. Several important extraction parameters have been optimized. The optimization results showed the type of organic solvent of n-hexane, the length of the hollow fiber of 1.5 cm, the volume of the sample solution of 20 mL, and the stirring speed of 600 rpm. The validation performance obtained a limit of detection (LoD) of 0.10 mgL-1, limit of quantification (LoQ) of 0.33 mgL-1, percent recoveries of 99.88%, a coefficient of variation of 3% (n=15), and the enrichment factor of 19,982 times. Under optimal conditions, the developed method was applied to extract diazinon in vegetable matrix samples using the spiking method. Mustard green was selected as a model matrix sample. From the research, the percentage recoveries of diazinon obtained in the mustard green matrix sample are 98.80% - 100.41%.

Hollow fiber–liquid phase microextraction method based on a new deep eutectic solvent for extraction and derivatization of some phenolic compounds in beverage samples packed in plastics

The present study describes a sensitive, efficient, and easy approach for isolation, enrichment, and derivatization some phenolic compounds in the beverage samples packed in plastic bottles. The sample preparation method is based on a hollow fiber–liquid phase microextraction technique using a deep eutectic solvent. The enriched analytes are determined by gas chromatography–mass spectrometry. For this purpose, a new deep eutectic solvent composed of 8–hydroxyquinoline and pivalic acid is synthesized and used as an extraction solvent. The solvent is mixed with chloroacetyl chloride as a derivatization agent and filled into a hollow fiber segment containing an iron wire within the lumen. The prepared stir bar (hollow fiber) is stirred into the sample solution in which sodium chloride is dissolved to increase ionic strength of the solution. Temperature of the solution is adjusted at 50 °C to improve efficiency of the extraction/derivatization procedure. Under optimum conditions, the introduced method indicated high enhancement (1652–3265) and enrichment (1085–1256) factors, low limits of detection (9–22 ng L−1) and quantification (29–76 ng L−1), good linearity (r2 ≥ 0.9950), and satisfactory repeatabilities. Finally, the proposed method was applied in analysis of the analytes in the various beverage samples packed in plastic packages.

Inorganic selenium speciation in water and biological samples by three phase hollow fiber-based liquid phase microextraction coupled with HPLC-UV

A rapid, sensitive, high clean-up and economic three phase hollow fiber liquid phase microextraction method followed by HPLC-UV was applied for speciation of inorganic selenium in water and biological samples.

Determination of Carotenoids in Egg Yolk by High Performance Liquid Chromatography with Vortex-Assisted Hollow Fiber Liquid-Phase Microextraction using Mixed Extraction Solvent.

A vortex-assisted hollow fiber liquid-phase microextraction method using a mixed solvent as the extraction solvent followed by high performance liquid chromatography diode-array detection was developed for the extraction and determination of two carotenoids including lutein and β-carotene from egg yolk. The method is based on the microextraction of carotenoids from sample solution into extracting agent (20 μL), which is located in the lumen of hollow fiber followed by vortex-mixing. The mixed solvent (1-octanol+1-undecanol, 6:4, v:v) was employed as extracting agent for it has suitable viscosity and compatible with carotenoids via hollow fiber. Vortex-mixing was utilized to provide effective and mild mixing of sample solution and increase the contact between analytes and boundary layers of the hollow fiber. Parameters influencing recoveries were investigated and optimized. Under the optimum conditions, the linear range of lutein and β-carotene were from 50 to 1,000 ng mL-1 The correlation coefficients of the calibration curves were >0.9982, relative standard deviations (n =5) were between 2.23% and 3.51% and the limits of detection were 0.038 and 0.045 μg mL-1 for lutein and β-carotene, respectively. The proposed method was successfully applied to the extraction and determination of caroteonids in egg yolk with the satisfactory relative recoveries (90.2-101.8%).

Hollow Fiber Liquid Phase Microextraction Method Combined with High-Performance Liquid Chromatography for Simultaneous Separation and Determination of Ultra-Trace Amounts of Naproxen and Nabumetone in Cow Milk, Water, and Biological Samples

A simple and highly sensitive method based on hollow fiber liquid phase microextraction combined with high-performance liquid chromatography and fluorescence detection has been developed for simultaneous separation, preconcentration, and determination of naproxen and nabumetone from water, wastewater, milk, and biological samples. Parameters affecting the microextraction efficiency were evaluated and optimized. Under optimum conditions (extractant (14 μL of 1-undecanol), sample pH (3.0), extraction time (20 min), stirring rate (600 rpm), temperature (45 °C), potassium chloride concentration (4.0 %) and sample volume (9 mL)), the limits of detection based on (S/N = 3) were 1.3 ng L−1 for naproxen and 2.9 ng L−1 for nabumetone. The intra- and inter-assay relative standard deviations for naproxen and nabumetone were in the ranges of 3.2–6.1 % and 6.5–9.5 %, respectively. The calibration curves were linear in concentration ranges of 4.0–300.0 ng L−1 and 9.0–300.0 ng L−1 for naproxen and nabumetone, respectively, with good coefficient of determination (r 2 > 0.999). The method was successfully applied to the determination of naproxen and nabumetone in cow milk, water, wastewater, human plasma, and urine samples.

Application of hollow fiber liquid phase microextraction for simultaneous determination of regulated and emerging iodinated trihalomethanes in drinking water

Trihalomethanes (THMs) are regulated disinfection by-products (DBPs) most commonly analyzed in quality control water supply due to their harmful effects on health. However, few data exist about the content of emerging iodo-trihalomethanes (I-THMs) which are present in drinking water at very low concentrations (in the order of ngL−1). For this reason a two-phase hollow fiber liquid phase microextraction method for the simultaneous determination of four regulated trihalomethanes and six emerging iodo-trihalomethanes using GC-μECD and GC–MS with detection limits in the range of few ngL−1 has been developed. A central composite design was used to optimize conditions for simultaneous extraction. The best extraction recovery was obtained with 19.2min at 27.1°C and 900rpm, without salt addition, using a supported hollow fiber membrane of 10.5cm (0.6mm id) and 1-octanol as acceptor phase. The limits of detection for the regulated THMs and I-THMs were 3–44ngL−1 and 1–3ngL−1, respectively. The calibration curves showed good linearity (R2>0.995) and good repeatibility (3–22%). The relative recoveries in water were between 96.5% and 105.2%. The method was applied for the simultaneous determination of trihalomethanes in supply water samples from seven water distribution systems (WDS) in the Huelva area, located at the southwest Spain, which use different water-treatment processes. The highest concentrations of I-THMs, particularly CHBrClI and CHCl2I, were detected in water treated with advanced treatment process using pre-ozonation, however these compounds were not detected or decreased along distribution system. In the samples of treated water with conventional treatment, using pre-oxidation by permanganate and distribution network, CHCl2I, CHBrClI, CHClI2, CHBrI2 and CHI3 were detected at very low concentrations (1–18ngL−1). Finally, in water samples from underground origin without oxidation treatment, in which only disinfection with sodium hypochlorite was applied, I-THMs were not detected.

Mesoporous carbon reinforced hollow fiber liquid-phase microextraction for the enrichment of phenylurea herbicides followed by their determination with high performance liquid chromatography

A mesoporous carbon reinforced hollow fiber liquid phase microextraction method was developed for the enrichment of phenylurea herbicides from water and soil samples.

Determination of 4′-isobutylacetophenone and other transformation products of anti-inflammatory drugs in water and sludge from five wastewater treatment plants in Sweden by hollow fiber liquid phase microextraction and gas chromatography–mass spectrometry

This work describes the development of a two-phase hollow fiber liquid phase microextraction method for the determination of three hydrophobic transformation products of the nonsteroidal anti-inflammatory drugs ketoprofen, ibuprofen and diclofenac: 3-acetobenzophenone, 4´-isobutylacetophenone and diclofenac amide. The optimized method involved extraction for 180min at a stirring speed of 440rpm. Hollow fibers (0.6mm i.d.) of 6cm length were employed and the acceptor phase consisted of 1-octanol. 5% Sodium chloride was added to samples to prevent loss of the solvent during extraction. Extracts were analyzed by GC–MS and method detection limits were in the range of 1.6–5.6ngL−1. The method was applied for the determination of target analytes in influent samples from five Swedish wastewater treatment plants (WWTPs). All three analytes were found in very low or non-detectable concentrations. The most abundant compound was 3-acetobenzophenone found at four of the investigated WWTPs at an average concentration of 62ngL−1. Diclofenac amide and 4′-isobutylacetophenone were only detected above LOD at one WWTP each at a concentration of 55 and 197ngL−1, respectively. Samples of water entering and exiting the activated sludge treatment as well as digested sludge were also collected from one of the WWTPs. Only diclofenac amide was detected in these samples. A higher concentration was detected in the effluent from the activated sludge treatment than the influent, thus indicating the formation of this compound during treatment. In the sludge, diclofenac amide was detected at 183ngg−1wet weight. Based on these results it can be concluded that the amounts of these compounds reaching WWTPs are very small, suggesting negligible risks to the aquatic environment. However, they also indicate the potential formation during the activated sludge process and accumulation into sludge for at least one of the compounds which is why further studies of these processes are needed.

Development of hollow fiber‐supported liquid‐phase microextraction and HPLC‐DAD method for the determination of pyrethroid metabolites in human and rat urine

A simple hollow fiber liquid-phase microextraction method for the determination of synthetic pyrethroid metabolites, 3-phenoxybenzoic acid and 4-hydroxy-3-phenoxybenzoic acid, in human and rat urine was developed and validated. A polypropylene hollow fiber tightly fitted onto a Nylon rod and impregnated with organic solvent served as a disposable extraction device. Desorption of analytes was carried out in NaOH solution, analyzed further by gradient HPLC and diode array detection method. Important factors were identified using Taguchi OA16 (4(5) ) orthogonal array design and further optimized using univariate approach. The optimum method performance was observed when 1 mL of urine hydrolyzed with 0.2 mL of concentrated HCl was further supplemented with 100 mg of NaCl and extracted for 120 min into dihexyl ether immobilized in the pores of the hollow fiber. Metabolites were desorbed into 0.1 mL of 0.1 M NaOH for another 120 min. Limits of detection and quantitation of 15 and 50 ng/mL were obtained for both analytes. Relative standard deviations of 1.6-12.6% over the linear range (50-10,000 ng/mL, r > 0.9906) were observed. Intra- and inter-day accuracies of the method ranged from 98.3 to 109.5% and from 93.3 to 110.9%, respectively. The optimized method was applied to the analysis of real urine samples collected from rats exposed orally to cypermethrin.

Analysis of ketoprofen enantiomers in human and rat plasma by hollow-fiber-based liquid-phase microextraction and chiral mobile-phase additive HPLC

A simple, inexpensive, and efficient preconcentration and cleanup three-phase hollow fiber liquid-phase microextraction method (HF-LPME) was developed for the extraction of the anti-inflammatory ketoprofen (KTP) from human and rat plasma and HPLC enantioseparation of its enantiomers using vancomycin as a chiral mobile-phase additive with an achiral C8 column. The effects of different parameters influencing the efficiency of extraction were optimized for aqueous samples. Under optimized conditions, KTP enantiomers were extracted from 0.5 mL of plasma diluted to 5 mL with salinated and acidified deionized water (pH = 2) with 25 μL of alkalinized acceptor phase (pH = 11) during 30 min at room temperature. The mean recoveries of (−)-(R)- and (+)-(S)-KTP were 72.8% and 70.9%, respectively. The quantification limit was 20 ng/mL with linear response over the 20–2000 ng/mL concentration range for both enantiomers. Assay precision was studied within-day and between-day using 100 ng/mL KTP solutions. For both KTP enantiomers, relative standard deviations were lower than 12%. The proposed microextraction method was applied for the extraction of KTP enantiomers from human and rat plasma samples after oral administration of pure (±)-KTP in 4 mg/kg dosage for rats and 50 mg dosage for humans to assess the enantiospecific bioavailability of KTP enantiomers in their plasma. In vivo inversion studies revealed that the bioavailability of S-KTP is higher than that of the R enantiomers in rat, but they are similar in human plasma. The developed method showed that HF-LPME is a promising technique for sample preparation for the analyses of chiral drugs in biological samples.

Graphene reinforced hollow fiber liquid-phase microextraction for the determination of phthalates in water, juice and milk samples by HPLC

A novel graphene reinforced hollow fiber liquid phase microextraction method was developed for the extraction of phthalates (PAEs) from water, juice and milk samples prior to their determination by high performance liquid chromatography. The main factors that affect the extraction efficiency, such as fiber length, concentration of graphene, extraction time, the pH and ionic strength of the sample solution, and stirring rate were investigated and optimized. Under the optimum conditions, the concentration factors for the analytes ranged between 59 and 71. The limits of detection (S/N = 3) of the method were between 0.2 and 1.2 ng mL−1 for water and juice samples, and between 2.5 and 5.0 ng mL−1 for milk samples. The recoveries of the method were in the range between 81.0% and 108.0% for water, juice and milk samples. The results indicated that the method was rapid, efficient and environmental friendly for the determination of PAEs in different matrix samples.

Sludge Removal of Nonsteroidal Anti-Inflammatory Drugs during Wastewater Treatment Studied by Direct Hollow Fiber Liquid Phase Microextraction

In this study, the fate of four common anti-inflammatory drugs (ketoprofen, naproxen, diclofenac and ibuprofen) within a wastewater treatment plant was investigated. A previously developed direct hollow fiber liquid phase microextraction method was applied to water as well as sludge samples collected from the primary, secondary and tertiary treatment respectively and the final analysis was performed by liquid chromatography quadropole time of flight tandem mass spectrometry. Enrichment factors ranged from 1400 to 3900 times depending on analyte and matrix. Method detection limits ranged from 0.3 to 14 ng/L for the different analytes and matrices. The overall sludge removal was 9%, 3%, 13% and 1% for ketoprofen, naproxen, diclofenac and ibuprofen respectively, thus indicating that of the studied compounds, ketoprofen and diclofenac to the largest extent partition into the sludge. For both substances, the largest fraction was found in secondary sludge (60% and 80% respectively of the total amount detected in the sludge). For naproxen and ibuprofen, the largest fraction were on the other hand detected in primary and tertiary sludge respectively, indicating that the affinity to the different sludge types might vary among the four drugs. The overall low sludge removal confirms existing theories that partitioning into sludge is only a minor removal mechanism for the investigated compounds. Nevertheless, naproxen and ibuprofen are still efficiently removed from the water during treatment (100% and 97 % total removal respectively) suggesting that these compounds are highly susceptible to biodegradation while ketoprofen and diclofenac (66% and 67% total removal respectively) appear more persistent.

Determination of the concentration of metoprolol tartrate in human plasma by HPLC coupled with hollow fiber liquid phase microextraction method

Objective: To establish a HPLC coupled with hollow fiber liquid phase microextraction(HF-LPME) method for determination of the concentration of metoprolol tartrate in human plasma.Methods: The concentrations of donor phase and receptive phase,time,temperature and rotary speed of extraction,and concentration of NaCl in HF-LPME were optimized.The hollow fiber was placed in plasma sample solution to perform microextraction,and then the extract was analyzed by HPLC method with fluorescence detection on Agilent Zorbax XDB-C18 column.The mobile phase consisted of methanol-0.1% phosphoric acid(40∶60) with a flow rate of 1 ml/min.The excitation wavelength was 227 nm and the emission wavelength was 305 nm.The column temperature was 30 ℃.Results: Metoprolol tartrate was in good linearity within the range of 2-125 ng/ml.The intra-day and inter-day RSD of low,middle and high concentrations(5,20,100 ng/ml) were all less than 10%,and recoveries were(87.1±7.3)%,(92.6±5.8)% and(89.1±2.5)%,respectively.Conclusion:HPLC coupled with HF-LPME method is suitable for analysis of concentration of metoprolol tartrate in human plasma.

Determination of partition coefficient and analysis of nitrophenols by three-phase liquid-phase microextraction coupled with capillary electrophoresis

A three-phase hollow fiber liquid-phase microextraction method coupled with CE was developed and used for the determination of partition coefficients and analysis of selected nitrophenols in water samples. The selected nitrophenols were extracted from 14 mL of aqueous solution (donor solution) with the pH adjusted to pH 3 into an organic phase (1-octanol) immobilized in the pores of the hollow fiber and finally backextracted into 40.0 microL of the acceptor phase (NaOH) at pH 12.0 located inside the lumen of the hollow fiber. The extractions were carried out under the following optimum conditions: donor solution, 0.05 M H(3)PO(4), pH 3.0; organic solvent, 1-octanol; acceptor solution, 40 microL of 0.1 M NaOH, pH 12.0; agitation rate, 1050 rpm; extraction time, 15 min. Under optimized conditions, the calibration curves for the analytes were linear in the range of 0.05-0.30 mg/L with r(2)>0.9900 and LODs were in the range of 0.01-0.04 mg/L with RSDs of 1.25-2.32%. Excellent enrichment factors of up to 398-folds were obtained. It was found that the partition coefficient (K(a/d)) values were high for 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol and 2,6-dinitrophenol and that the individual partition coefficients (K(org/d) and K(a/org)) promoted efficient simultaneous extraction from the donor through the organic phase and further into the acceptor phase. The developed method was successfully applied for the analysis of water samples.