Hollow Fiber Solid Phase Microextraction Research Articles

Polyoxometalate @ carbon spheres composite reinforced hollow fiber for solid phase microextraction of some pyrethroids and their determination

A novel H3PW12O40@CS composite was prepared for the first time and utilized as a sorbent in the hollow fiber-solid phase microextraction (HF-SPME) method for the extraction of deltamethrin and cypermethrin (as a class of synthetic insecticides) from real samples using HPLC-UV. The presence of oxygen functional groups on the H3PW12O40, enhanced the interactions with selected analytes. The synergistic effect between H3PW12O40 as a sorbent and CS as a substrate with high-surface area significantly increased the extraction efficiency. The proposed method, can offer simultaneous extraction, purification and preconcentration in one step. Regarding, the clean-up ability of HF, only initial dilution with water is required before the extraction process. Also, the figures of merit were calculated at optimal conditions. Based on the results, linear dynamic range was 5 × 10−4– 0.5 µg mL−1 while, the R2 exceeded 0.9927. Also, limits of detection (LODs) and limits of quantification (LOQs) were 1.9 × 10−4–2.1 × 10−4 µg mL−1, and 5.7 × 10−4– 6.3 × 10−4 µg mL−1, respectively. The inter-day and intra-day relative standard deviation (RSD%) were calculated in the concentration of 5 × 10−4, 5 × 10−3 and 5 × 10−2 µg mL−1, which ranged in 3.40 % − 5.80 %. Finally, HF-SPME method was used for determination of target analytes in celery, cabbage and zucchini juices. Therefore, prepared method has advantages such as an inexpensive, simple and environmentally friendly synthesis, fast operation, low LOD and wide linear dynamic range.

Hollow fiber-solid phase microextraction of fatty acid methyl esters from wastewater coupled with micro sample collector assisted injection technique

Hollow fiber-solid phase microextraction combined with micro sample collector assisted injection technique was developed for the detection of trace fatty acid methyl esters in biodiesel wastewater. Polypropylene hollow fiber was employed as extraction material to absorb fatty acid methyl esters in biodiesel wastewater. After the adsorption, hollow fiber was sleeved on the needle core of a micro sample collector and introduced directly into a GC injector for thermal desorption of the analytes. The selectivity of polypropylene hollow fiber on fatty acid methyl esters was investigated by extracting common pollutants in wastewater. Under the optimal conditions, the enrichment factors of polypropylene hollow fiber for methyl palmitate, methyl linoleate, methyl oleate, and methyl stearate were tested as high as 471, 287, 527, and 801, respectively. The quantitative method was validated and the linearity was satisfactory over a concentration range of 10–2000 µg/L with the correlation coefficients more than 0.9990 for 4 fatty acid methyl esters. The limits of detection and quantification were 0.04–0.40 µg/L and 10.0 µg/L, respectively. The recoveries were in the range of 92.0–116.7% by analyzing actual spiked samples. The results showed that the established method was suitable for the analysis of trace fatty acid methyl esters in water samples, with simple operation, low cost and environmental friendliness.

ZIF-8-90 @ graphene oxide reinforced porous hollow fiber coupled with deep eutectic solvent for hollow fiber solid-phase microextraction of selected phthalate esters followed by quantification through high-performance liquid chromatography-ultraviolet detection

The present study was conducted to synthesize hybrid MOFs with a high effective surface area consisting of ZIF-8 and ZIF-90 on the surface of Graphene Oxide (GO). The hybrid ZIF-8-90@GO was finally placed inside the Hollow Fiber (HF) pores to use the substrate filtration properties. Then, the extraction device was used to extract three selected phthalate esters including DiMethyl Phthalate (DMP), DiEthyl Phthalate (DEP) and DiButyl Phthalate (DBP) (as the model analytes) followed by back extraction using Deep Eutectic Solvent (DES). Herein, the DES was utilized as a suitable and effective alternative to common toxic desorption solvents, and it led to the greening of the method. In order to achieve maximum efficiency and sensitivity, the parameters influencing on extraction and desorption processes were optimized. In the obtained optimum situation, the method linearity, Limits Of Detection (LODs), Limits Of Quantification (LOQs), Relative Standard Deviations (RSDs%), Enrichment Factors (EFs) were equal to 0.1–500 µg/L, 0.026–0.058 µg/L, 0.089–0.194 µg/L, 1.8 to 4.7% and 45.4–47.1, respectively. The obtained coefficients of determination (r2) were also higher than 0.9990. The Extraction Recovery (%ER) values were also 90, 87 and 91%, respectively for DMP, DEP and DBP. The above-mentioned method was used for the analysis of water and juice samples and acceptable results were obtained. The obtained relative recoveries in the real samples were in the range of 90–103%. Moreover, due to the presence of aldehyde and methyl groups with hydrophilic and hydrophobic properties in the structure of the synthesized hybrid sorbent, the possibility of interaction increased between sorbent and the studied species, and it per se, led to the increase of extraction efficiency.

Keggin type phosphotungstic acid intercalated copper-chromium-layered double hydroxide reinforced porous hollow fiber as a sorbent for hollow fiber solid phase microextraction of selected chlorophenols besides their quantification via high performance liquid chromatography

Herein, a copper-chromium-layered double hydroxide (Cu/Cr-LDH) was synthesized by the co-precipitation method. The Cu/Cr-LDH was intercalated to the Keggin-type polyoxometalate (H3PW12O40). The modified LDH accommodated in the pores of hollow fiber (HF), to prepare the extracting device for the HF-solid phase microextraction method (HF-SPME). The method was used for the extraction of 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6- trichlorophenol from tap water, river water, and tea sample. The extracted target analytes were quantified via high-performance liquid chromatography-UV detection. The figures of merit of the method such as, linear dynamic ranges (LDRs), limit of detections (LODs) and, limit of quantifications (LOQs), were determined based on the obtained optimum condition. Based on the results, the LDR was between 1 and 500 μg L − 1 and r2 higher than 0.9960. The LODs and LOQs were obtained in the ranges of 0.28–0.36 µg L − 1 and 0.92–1.1 µg L − 1, respectively. The relative standard deviations ((RSDs% for inter-and intra-day) of the method for the extraction of target analytes were calculated in two different concentrations of (2 and 10 μg L − 1) and (5 and 10 μg L − 1) between 3.70% - 5.30% and 3.50% - 5.70%-respectively. The enrichment factors were obtained between 57 and 61. In order to investigate the accuracy of the method, also the relative recovery was obtained, between 93 and 105%. Finally, the proposed method was used for the extraction of the selected analytes in different water and tea samples.

Hollow Fiber-Solid Phase Microextraction of Polycyclic Aromatic Hydrocarbons from Environment Water Followed by Flash Evaporation GC/MS

Hollow Fiber-Solid Phase Microextraction of Polycyclic Aromatic Hydrocarbons from Environment Water Followed by Flash Evaporation GC/MS

Preyssler heteropolyacid supported on magnetic silica for hollow fiber solid-phase microextraction of anti-hypertensive drugs in human hair

Preyssler heteropolyacid supported on magnetic silica for hollow fiber solid-phase microextraction of anti-hypertensive drugs in human hair

In-situ synthesis of nanocubic cobalt oxide @ graphene oxide nanocomposite reinforced hollow fiber-solid phase microextraction for enrichment of non-steroidal anti-inflammatory drugs from human urine prior to their quantification via high-performance liquid chromatography-ultraviolet detection

The in-situ synthesis and application of nanocubic Co3O4-coated graphene oxide (Co3O4@ GO) was introduced for the first time to present a cost-effective, stable and convenient operation and a simple device for hollow fiber solid-phase microextraction (HF-SPME) of four selected nonsteroidal anti-inflammatory drugs (NSAIDs) including diclofenac, mefenamic acid, ibuprofen and indomethacin. The extracted analytes were desorbed by an appropriate organic solvent and analyzed via high-performance liquid chromatography-ultraviolet detection (HPLC-UV). The prepared sorbent was approved using different characterization methods such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The variables effective on the Co3O4@GO-HF-SPME method including extraction time, desorption time, desorption solvent volume, sample pH, stirring rate and ionic strength were screened via Plackett–Burman design and then optimized by Box–Behnken design. Under optimal condition, the calibration curves were linear within the range of 1.0–200.0 µg L−1 of analyte concentration with detection limits of 0.18–1.1 µg L−1 and the relative standard deviations less than 10.1%. The limits of quantification (LOQs) were in the range of 0.60–3.67 µg L−1. Matrix effect was not observed with this method; therefore, standard addition is not necessary for quantification of target compounds. The enrichment factors were obtained in the range of 49–68. The relative recoveries of the urine sample analysis were calculated in the range of 93–102%. Finally, the presented method exhibited good sensitivity, excellent repeatability, high reusability and acceptable precision, which will be a promising method to analyze various nonsteroidal anti-inflammatory drugs in urine samples.

MIL-101 (Cr) @ graphene oxide-reinforced hollow fiber solid-phase microextraction coupled with high-performance liquid chromatography to determine diazinon and chlorpyrifos in tomato, cucumber and agricultural water

An effective, sensitive, relatively-fast and cost-effective method was developed to determine two types of selected organophosphorus pesticides (OPPs) including diazinon and chlorpyrifos in tomato, cucumber and agricultural water samples through applying MIL-101@ graphene oxide-reinforced hollow fiber solid-phase microextraction (MIL-101@GO–HF–SPME). The extracted analytes were desorbed via organic solvent and analyzed through high-performance liquid chromatography-ultraviolet detection (HPLC-UV) after extraction. MIL-101@ GO sorbent which was previously prepared and characterized was first dispersed in methanol by ultrasonication and then immobilized into the pores of a hollow fiber (HF). Several factors involved in MIL-101@GO–HF–SPME experiment such as desorption volume, ionic strength, desorption time, sample pH, extraction time and stirring rate were screened via Plackett–Burman design and then optimized through Box–Behnken design with the purpose of reaching the highest extraction efficiency. The above method showed a good linear range (1–500 μg L−1) with coefficient of determination higher than 0.9948, low limits of determination (LODs, 0.21 and 0.27 μg L−1), acceptable limits of quantifications (LOQs, 0.72 and 0.91 μg L−1), good enrichment factors (EFs, 49 and 41), acceptable absolute recoveries (AR%, 49 and 41%) and good spiking recoveries (88–104%) under the optimized condition at three different spiked levels for chlorpyrifos and diazinon, respectively. It is worth mentioning that due to the clean-up function of HF, there is no time-consuming sample pretreatment procedure (e.g. filtration or centrifugation) prior to the microextraction. Therefore, the presented method took advantage of both excellent adsorption performance of MIL-101@GO and the clean-up function of HF. The results confirmed that the presented method would be promising for the analysis of various types of these pesticides in environmental and vegetable samples.

Malathion determination in Rice samples with Graphene oxide reinforced hollow fiber-solid phase microextraction by GC-MASS

A method for applicability of the solid phase microextraction (SPME) procedure for determination of trace amounts of the organophosphorus pesticide malathion by gas chromatography - mass spectrometry (GC-MS) was developed. Graphene oxide reinforced sol–gel which was placed in hollow fiber (HF-SPME) was used for pre-concentration of malathion. In the present study the Plackett-Burman (PB) factorial design was used as a method for first monitoring of Eight factors that have a significant impact and optimized them in next stage, optimization process of significant factor was carried out using a five-level CCD after screening by PBD. the following conditions were selected for the analytical method of Malathion in real sample: amount of GO (0.01gr), pH of aqueous solution (pH: 3), volume of aqueous solution (10000 µl), volume of organic solvent (250 µl), adsorption time (35 min), desorption time (30 min), stirring rate of solution (1000 rpm) and amount of salt (4%). Calibration curves were plotted using three spiking levels of malathion in the concentration ranges of 0.2–0.4-0.5 ng/mL with correlation coefficients (r 2 ) 0.9914 for analytes. Under the optimized extraction conditions, the method showed good linearity (0.05–0.5 ng/mL), repeatability, low limits of detections (3.9×10 -3 ng/mL) and excellent pre-concentration factors (4000). The optimum conditions which were evaluated then applied for the analysis of malathion in the rice as a real sample

Hollow fiber-solid phase microextraction of phthalate esters from bottled water followed by flash evaporation gas chromatography-flame ionization detection

A solid phase microextraction coupled with flash evaporation gas chromatography method was applied to the determination of phthalate esters (PAEs). Polysulfone (PSF) hollow fiber at 1 cm length was employed as extraction element to adsorb PAEs directly. Predominant parameters including stirring velocity, salt concentration, extraction time and extraction temperature were optimized. PSF fiber with absorbed PAEs was put into a small sample cup. The extracted analytes were thermally desorbed at 300 °C in a pyrolyzer, and then entered into a column for separation. The linearity of the method was satisfactory over a concentration range of 2–1000 µg/L with the correlation coefficients r>0.99 for all analytes except dimethoxyethyl phthalate. The relative standard deviations for peak areas were below 9.5% (n = 6). The developed technique achieved high enrichment factors (280–9930 times) and low limits of detection (0.001–0.130 µg/L). The recoveries over the range of 87.0–117.7% were obtained by analyzing real spiked samples. The results demonstrated that this was a simple, environmentally friendly and accurate method for the determination of PAEs in bottled water samples.

Aflatoxins’ Clean-Up in Food Samples by Graphene Oxide–Polyvinyl Poly Pyrrolidone—Hollow Fiber Solid-Phase Microextraction

The present investigation reports the synthesis of graphene oxide–polyvinyl poly pyrrolidone composite and its application in the extraction of aflatoxins in food samples. This composite was successfully synthesized and characterized with analytical instruments such as UV–Vis, FITR, XRD, and SEM techniques. The extraction was carried out by reinforced hollow fiber liquid-phase microextraction coupled with high-performance liquid chromatography (HPLC). Various parameters that affect the productivity of the present technique were exhaustively explored, and the quantifications were carried out under the optimized states. The limits of detection (LODs) were found to be 0.33, 0.10, 0.37, and 0.10 ng g−1, and limits of quantification (LOQs) were 1.10, 0.33, 1.24, and 0.33 ng g−1, respectively, for aflatoxins B1, B2, G1, and G2. The accuracy of the present method was determined based on the relative recovery (RR%) of the aflatoxins and the RR% of aflatoxins B1, B2, G1, and G2 which were found to be quite good (between 60.20 and 108.20 for 1 ng g−1 and between 62.02 and 95.39 for 5 ng g−1) in food samples. Applicability of the sorbent for the separation and quantification of the above-mentioned aflatoxins from food samples were examined. The developed method is straightforward, reliable, and effective, and has been successfully applied in determination of aflatoxins from food samples.

β-cyclodextrin coated graphene oxide nanoadsorbents on the hollow fiber-solid phase microextraction and electrochemical monitoring of acetaminophen

β-cyclodextrin coated graphene oxide nanoadsorbents on the hollow fiber-solid phase microextraction and electrochemical monitoring of acetaminophen

Preconcentration and Determination Of Fluoxetine and Norfluoxetine in Biological and Water Samples with β-cyclodextrin Multi-walled Carbon Nanotubes as a Suitable Hollow Fiber Solid phase Microextraction Sorbent and High Performance Liquid Chromatography

‒A simple, selective and sensitive hollow fiber solid phase microextraction (SPME) combined with HPLC for the determination of fluoxetine (FLX) and norfluoxetine (NFLX) in human urine and real water samples has been developed and fully validated. Two solid phase microextraction sorbents, β-cyclodextrin functionalized multi-walled carbon nanotubes (βCD-MWCNTs) and acyl chloride functionalized MWCNTs, were synthesized and placed in the surface and pores of polypropylene hollow fiber by sol‒gel technique. In order to compare the analytical performance of βCD-MWCNTs as a new SPME sorbent with acyl chloride functionalized MWCNTs and MWCNTs, the hollow fiber device was directly immersed into the sample solution under a magnetic stirring. The βCD-MWCNTs are quite effective for extraction of fluoxetine and norfluoxetine. The extraction parameters such as pH of donor phase, donor phase volume, stirring rate, extraction time, type and volume of desorption solvent, and desorption time were thoroughly optimized. Under optimal conditions, the proposed method shows good linearity in the range of 1‒340 and 0.9‒360 ng/mL with a correlation coefficients of 0.9952 and 0.9967, low limits of detection of 0.4 and 0.3 ng/mL, and the high pre-concentration factors of 144 and 151 for determination of FLX and NFLX, respectively. Usage of proposed method for determination of FLX and NFLX in human urine and real water samples demonstrated a promising, simple, selective and sensitive sample preparation and determination method that can be applied in routine analysis.

Fabrication of polypyrrole-silver nanocomposite for hollow fiber solid phase microextraction followed by HPLC/UV analysis for determination of parabens in water and beverages samples

In the present study, a nanocomposite of polypyrrole-silver nanoparticles was made as a new sorbent of hollow fiber solid-phase microextraction method and it was utilized for the preconcentration and determination of trace amounts of parabens in water, fruit juice, and beer samples. Polypyrrole was synthesized by chemical oxidative polymerization on the wall surface of a hollow fiber. Then a green method was employed for the synthesis of silver nanoparticles on the polypyrrole. This coating showed impressive mechanical and chemical stability. Hollow fiber as solid phase microextraction fiber is conformable with complex matrices and exhibits high clean up and selectivity without memory effect due to its porosity. A number of significant factors were optimized. The limit of detection, under the optimal conditions, for all of the parabens was in 0.01 μg L−1. The method exhibited good linearity in the range of 0.05–200 μg L−1, with limit of quantification of 0.05 μg L−1, coefficients of determination better than 0.9990 and extraction recoveries of 25.0–28.0%. The intra- and inter-assay precisions (RSD%, n = 3) were in the range of 2.4–3.1 % and 3.4–4.2%, respectively. The relative recovery values for the spiked samples were in the acceptable range of 90.4–104.0%.

Multiwall carbon nanotube- zirconium oxide nanocomposite hollow fiber solid phase microextraction for determination of polyaromatic hydrocarbons in water, coffee and tea samples

The purpose of this study was to evaluate the application of hollow fiber solid-phase microextraction (HF-SPME) followed by HPLC-UV to determine the ultra-trace amounts of polycyclic aromatic hydrocarbons (PAHs) as model analytes in complex coffee and tea samples. HF-SPME can be effectively used as an alternative to the direct immersion SPME (DI-SPME) method in complex matrices. The DI-SPME method suffers from serious limitation in dirty and complicated matrices with low sample clean-up, while the HF-SPME method has high clean-up and selectivity due to the high porosity of hollow fiber that can pick out analyte from complicated matrices. As a hollow fiber sorbent, a novel multiwall carbon nanotube/zirconium oxide nanocomposite (MWCNT/ZrO2) was fabricated. The excellent adsorption of PAHs on the sorbent was attributed to the dominant roles of π–π stacking interaction and hydrophobic interaction. Under the optimized extraction conditions, the wide linear range of 0.1–200 μg L−1 with coefficients of determination better than 0.998 and low detection limits of 0.033–0.16 μg L−1 with satisfactory precision (RSD < 6.6%) were obtained. The relative recoveries obtained by spiking the PAHs in water, coffee and tea samples were in the range of 92.0–106.0%. Compared to other methods, MWCNT/ZrO2 hollow fiber solid phase microextraction demonstrated a good capability for determination of PAHs in complex coffee and tea samples.

N-doped carbon nanotubes-reinforced hollow fiber solid-phase microextraction coupled with high performance liquid chromatography for the determination of phytohormones in tomatoes

A N-doped carbon nanotubes-reinforced hollow fiber solid-phase microextraction (N-doped CNTs-HF-SPME) method was developed for determination of two naphthalene-derived phytohormones, 1-naphthalene acetic acid (NAA) and 2-naphthoxyacetic acid (2-NOA), at trace levels in tomatoes. N-doped CNTs were dispersed in ultrapure water with the assistance of surfactant, and then immobilized into the pores of hollow fiber by capillary forces and sonification. The resultant N-doped CNTs-HF was wetted with 1-octanol, subsequently immersed into the tomato samples to extract the target analytes under a magnetic stirring, and then desorbed with methanol by sonication prior to chromatographic analysis. Compared with CNTs, the surface hydrophilicity of N-doped CNTs was improved owing to the doping of nitrogen atoms, and a uniform dispersion was formed, thus greatly simplifying the preparation process and reducing waste of materials. In addition, N-doped CNTs-HF exhibits a more effective extraction performance for NAA and 2-NOA on account of the introduction of Lewis-basic nitrogen. It is worth to mention that owing to the clean-up function of HF, there are not any complicated sample pretreatment procedures prior to the microextraction. To achieve the highest extraction efficiency, important microextraction parameters including the length and the concentration level of N-doped CNTs in surfactant solution, extraction time, desorption conditions such as the type and volume of solvents, pH value, stirring rate and volume of the donor phase were thoroughly investigated and optimized. Under the optimal conditions, the method showed 165- and 123-fold enrichment factors of NAA and 2-NOA, good inter-fiber repeatability and batch-to-batch reproducibility, good linearity with correlation coefficients higher than 0.9990, low limits of detection and quantification (at ng g−1 levels), and satisfactory recoveries in the range of 83.10–108.32% at three spiked levels. The proposed method taking advantages of both excellent adsorption performance of N-doped CNTs and the clean-up function of HF, was a simple, green, efficient and cost-effective enrichment procedure for the determination of trace NAA and 2-NOA in tomatoes.

Bis(trifluoromethylsulfonyl)imide-based frozen ionic liquid for the hollow-fiber solid-phase microextraction of dichlorodiphenyltrichloroethane and its main metabolites.

1-Hexadecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide is a solid-phase ionic organic material under ambient temperature and is considered as a kind of "frozen" ionic liquid. Because of their solid-state and ultra-hydrophobicity, "frozen" ionic liquids are able to be confined in the pores of hollow fiber, based on which a simple method was developed for the hollow-fiber solid-phase microextraction of dichlorodiphenyltrichloroethane and its main metabolites. Under optimized conditions, the proposed method results in good linearity (R2 > 0.9965) over the range of 0.5-50μg/L, with low limits of detection and quantification in the range of 0.33-0.38 and 1.00-1.25μg/L, respectively. Intra- and interday precisions evaluated by relative standard deviation were 3-6 and 1-6%, respectively. The spiked recoveries of dichlorodiphenyltrichloroethane and its main metabolites from real water samples were in the range of 64-113 and 79-112%, respectively, at two different concentration levels. The results suggest that "frozen" ionic liquids are promising for use as a class of novel sorbents.

Dendrimer-reinforced sol-gel based hollow fiber solid-phase microextraction for citalopram determination using response surface methodology.

The inclusion of a polyamidoamine dendrimer in a silica sol-gel yielded a solid nanosorbent that was used for the preconcentration, extraction, and determination of citalopram in hospital waste water, hemodialysis solution, and some drinking water. The method was developed by applying a novel nanosorbent for the solid-phase microextraction of citalopram, containing a silica sol-gel reinforced by polyamidoamine second-generation dendrimer, which was protected by a polypropylene hollow fiber. Plackett-Burman design and central composite design were utilized to evaluate the significance of several factors on the extraction efficiency. The adsorption mechanism and thermodynamic and kinetic aspects were studied. The adsorption process was exothermic and well fitted to the Bangham equation kinetic model. Under optimal conditions, the presented method was liner in the range of 0.05-100μg/mL. The limits of detection of quantification of citalopram were 0.0095 and 0.031μgm/L, respectively.

Design and application of a novel integrated microsampling system for simultaneous collection of gas- and particle-phase semivolatile organic compounds

An integrated microsampling approach based on active microextraction was developed to study semivolatile organic compounds (SVOCs). This microsampling system included an in-tube hollow-fiber solid-phase microextraction device in combination with a sorbent tube that can be applied in parallel to collect gas- and particle-phase SVOCs. The preparation procedure, theory, and application of two devices were characterized and validated by the single fiber theory and scanning mobility particle sizer experiments. The influence of the optimization parameters (sampling time, flow rate, and breakthrough volume) on the extraction process was studied in detail. The performance of the system was tested via simultaneous collection of a range of gas and particle samples of ethylbenzene, xylenes, n-alkanes, polycyclic aromatic hydrocarbons, and monoterpenes. The collection efficiencies of the two devices were more than 90% for most target compounds. Typically, relative standard deviation values in the range 2–6% were obtained, depending on the compound. The calibration curves for each compound were reproducible and linear over the concentration ranges normally found in atmospheric samples. Both devices were used to collect ambient air samples during a haze period and performed well in the extraction of both gas- and particle-phase SVOCs at the ng m−3 levels. The results from phase studies were used for further evaluation of the gas/particle partitioning of SVOCs. Application of this integrated microsampling system in the field validated its use as a simple, rapid, reusable, and cost-effective screening tool.

Hollow fiber–stir bar sorptive extraction and microwave assisted derivatization of amino acids in biological matrices

A kind of solid phase microextraction configuration combining the principles of hollow fiber solid phase microextraction (HF–SPME) and stir bar sorptive extraction (SBSE) is presented. The main feature of HF–SBSE is the use of microporous hollow fiber acting as the carrier and filter, while a thin stainless steel wire and silica microspheres in the lumen of hollow fiber respectively acting as the magnetic stirrer and the dispersed sorbents for the collection and extraction of the target analytes, thus affording extraction process like SBSE. Moreover, the prepared hollow fiber stir bar was applied to direct microextraction and microwave assisted derivatization with N,O–Bis(trimethylsilyl)trifluroacetamide (BSTFA) of four amino acids in rats’ urine and cerebrospinal fluid followed by gas chromatography mass spectrometric analysis. The limits of detection for four amino acids were found to be in the range of 0.0003–0.017μgmL−1, and all the analytes did not exhibit any lack of fit. The extraction recoveries using HF–SBSE techniques ranged from 71.8% to 102.3%. The results indicated that hollow fiber stir bar sorptive extraction was a promising technique for the enrichment and direct derivatization of analytes extracted from biological matrices without sample clean–up.