Search

Adenine nucleotides (ANs)—adenosine 5′-triphosphate (ATP), adenosine 5′-diphosphate (ADP), and adenosine 5′-monophosphate (AMP)—are essential for energy transfer and the supply of countless processes within cellular metabolism. Their concentrations can be expressed as adenylate energy charge (AEC), a measure of cellular metabolic energy that directly correlates with the homeostasis of the organism. AEC index has broad diagnostic potential, as reduced ATP levels are associated to various conditions, such as inflammatory diseases, metabolic disorders, and cancer. We introduce a novel methodology for rapid isolation, purification, and quantification of ANs from a single drop of capillary blood. Of all the stationary phases tested, activated carbon proved to be the most efficient for the purification of adenine nucleotides, using an automated micro-solid phase extraction (µ-SPE) platform. An optimized µ-SPE method, coupled with RP-HPLC and a run time of 30 min, provides a reliable analytical framework for adenine nucleotide analysis of diverse biological samples. AN concentrations measured in capillary blood samples were 1393.1 µM, 254.8 µM, and 76.9 µM for ATP, ADP, and AMP molecules aligning with values reported in the literature. Overall, this study presents a streamlined and precise approach for analyzing ANs from microliters of blood, offering promising applications in clinical diagnostics. [ABSTRACT FROM AUTHOR]

A new analytical method combining magnetic micro‐solid phase extraction (μ‐SPE) in tandem with high‐performance liquid chromatography‐ultraviolet (HPLC‐UV) analysis was developed and used for the simultaneous extraction/preconcentration of tetracycline (TC) and oxytetracycline (OTC) residues in drug manufacturing effluents. The μ‐SPE conducted by the introduction of iron oxide reduced‐graphene oxide (MrGO) doped tin‐lanthanium intercalated with thiosulfate ions to produce magnetic LDH (MrGO/Sn‐La‐S). The adsorbent was synthesized and characterized using x‐ray diffraction, Fourier transform infrared, scanning electron microscopy, energy‐dispersive x‐ray, elemental mapping, transmission electron microscopy, x‐ray photoelectron spectroscopy, and value stream mapping techniques. The effective parameters, including the extraction and desorption steps, were investigated and optimized. Under optimized conditions, the limits of detection (LOD) for TC and OTC were obtained as 5.42 and 3.31 μg.L−1, respectively, while the linearity was in the range of 10.0–500.0 μg.L−1 for both antibiotics with satisfactory determination coefficients (R2) of 0.9811 and 0.9846 for TC and OTC, respectively. The recovery percentages for the analytes in real samples were achieved in the ranges of 89.2%–101.6% and 91.0%–101.3% for TC and OTC antibiotics, respectively. All these features proved the potential of the developed method and adsorbent for real world applications. [ABSTRACT FROM AUTHOR]

A polypyrrole (PPy)-cotton pad sorbent enclosed in tea bag envelope was developed and used in micro-solid phase extraction (µ-SPE) for the determination of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). After extraction, the extract was qualified and quantified by a gas chromatograph equipped with a flame ionization detector (GC-FID). Parameters influencing this developed method and the efficiency of µ-SPE were studied and optimized. Under the optimal conditions, the developed method provided good linearity in a concentration range of 0.100–100 µg L−1 for BHA and 0.050–50 µg L−1 for BHT, respectively. The limits of detection were 39.27 ± 0.52 ng L−1 for BHA and 16.96 ± 0.17 ng L−1 for BHT. Satisfactory relative recoveries of BHA and BHT were achieved in the range from 86.8 ± 1.9 to 117.1 ± 2.3% with acceptable relative standard deviation (RSD) below 8.1%. Good reproducibility was obtained with RSDs < 3.1%, for n = 6. The developed adsorbent is easy to operate, low cost, eco-friendly, reusable, with high extraction efficiency, and was successfully applied in the simultaneous synthetic antioxidant determination of non-alcoholic beverage samples. [ABSTRACT FROM AUTHOR]

Hydrophilic molecularly imprinted chitosan microspheres (HMICS) were synthesized using deep eutectic solvents (DESs)-(3-aminopropyl) triethoxysilane (APTES) as co-functional monomer for the extraction of catechin from green tea with micro-solid phase extraction (micro-SPE). Various factors were studied to optimize the extraction condition during extraction process. The actual extraction amount under the optimal conditions (amount of adsorbent (20 mg), type and volume of washing (acetone, 1.2 mL) and eluting solvent (acetone/acetic acid, 1.0 mL), extraction time (30 min), extraction temperature (40 °C), and sample pH (4)) were obtained at 97.06 mg·g−1. The catechin recovery ranged with ranged with limit of detection (LOD) within 0.09–0.24 µg·mL−1, and limit of quantification (LOQ) within 0.18–0.28 µg·mL−1. From the experimental results in this system, the HMICS was proved to have higher extraction capacity, improving as a promising adsorbent for the extraction of catechin. [ABSTRACT FROM AUTHOR]

Melamine-modified MIL-88 was synthesized through the solvothermal method and utilized as the extracting device for the µ-solid phase extraction (µ-SPE) of selected volatile organic compounds (VOCs) including benzene, toluene, ethylbenzene, and isomers of xylene (BTEXs) from different environmental water samples. The prepared melamine-MIL-88 (Fe) was enclosed inside the porous hydrophilic tea bag filter membrane. The sealed membrane containing the sorbent (15 mg) was used as the µ-SPE device. The quantification of the extracted BTEXs was done by gas chromatography-mass spectrometry (GC-MS) instrument. The prepared sorbent was confirmed by different characterizations including powdered X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transformed infrared (FT-IR) spectroscopy. The method provided linearity range of 0.5–500.0 µg L−1 (depending on target analytes) and coefficients of determination (R2) with the range of 0.9891–0.9981 under the optimum condition. The enrichment factors (EFs) were found to be between 39.0 and 48.0. The limits of detection (LODs) were also calculated to be between 0.08 and 0.42 µg L−1, while the range of corresponding absolute recoveries was in the range of 78–96%. The method relative standard deviations (RSDs) ranged from 5.5 to 11.8% (at 5.0 µg L−1). Moreover, the prepared melamine-MIL-88 (Fe) showed high adsorption capacity (130 mg g−1). The method is cost-effective, user-friendly, and with minimal consumption of organic solvent. In addition, melamine-MIL-88 has not yet been synthesized and investigated in the microextraction of the pollutants. [ABSTRACT FROM AUTHOR]

In the present study, electrospun zeolitic imidazolate framework-8/poly(lactic acid) nanofibers were successfully synthesized and characterized as a potential nanosorbent for the pipette-tip micro-solid phase extraction of chlorpropham, pirimicarb, carbaryl, and methiocarb carbamate insecticides from environmental water samples. The extraction procedure was followed by gas chromatography/mass spectrometry separation and determination of the target analytes. All the effective parameters of the extraction procedure were optimized through the one variable at-a-time method. Thanks to the very simple extraction procedure as well as the application of electrospun nanofibers with high surface area, the four analytes were efficiently extracted with as lowest extraction times as practicable. Under the optimal conditions, the calibration plots of the analytes were obtained within broad linear dynamic ranges of 0.5 – 150 ng mL−1 for chlorpropham and pirimicarb plus 1.0 – 175 ng mL−1 for carbaryl and methiocarb, respectively. Besides, limits of detection as low as 0.2 and 0.15 ng mL−1 for chlorpropham and pirimicarb, respectively, as well as 0.5 ng mL−1 for carbaryl and methiocarb indicate the favorable sensitivity of the analytical procedure. The applicability of the developed method was evaluated by quantitative determination of the target analytes in four different environmental water samples. Relative recoveries higher than 88.0% shows the acceptable accuracy of the method in the quantitative determination of the four carbamate insecticides.

Abstract This work developed a fast and simple method for the quantification of two important β-agonists, ractopamine (RAC) and clenbuterol (CLEN) in animal urines. The method was based on micro-extraction by a mixed mode monolithic material and analysis by HPLC-UV and UHPLC-Q ExactiveTM Plus Orbitrap mass spectrometer. A mixed functional monolith with nonpolar ester-based structure containing polar carboxylic groups was thermally synthesized in situ in the pipette tips. The material combines both hydrophobic and ionic interactions. Parameters including conditions and composition of reagents for the in-pipette tip monolith synthesis, as well as the extraction process, were investigated and optimized. The procedure for extraction is 800 μL washing solvent of 10:90 (v/v) ACN:water and 150 μL eluting solvent of 30:70 (v/v) ACN:200 mM acetate buffer pH 4.0. Extraction efficiencies of 92% and 100% for RAC and CLEN, respectively, were achieved within 5 min with total organic solvent consumption of 395 μL. The extracts of spiked cattle and swine urines were analyzed by HPLC-UV and UHPLC-Q ExactiveTM Plus Orbitrap mass spectrometer. Good recovery with acceptable precision was observed. The mass spectrometry data confirmed efficient matrix removal by the synthesized extraction sorbent allowing routine analysis by the HPLC-UV method.

[Display omitted] • Melamine sponge anchoring with Ni/Al-LDH was selected as adsorbent. • A facile and green sorbent for micro-SPE was investigated. • Eco-friendliness was confirmed by Analytical Eco-scale and Analytical GREEnness metric (AGREE). • An effective sorbent was successfully applied for extraction of triazoles in surface water, soymilk, honey and egg yolk matrices. In this work, a facile and green alternative method for preconcentration of triazole fungicides (TFs) using melamine sponge anchoring with nickel/aluminium layered double hydroxide (Ni/Al-LDH-MS) as adsorbent for micro-solid phase extraction (micro-SPE). LDHs was prepared by nickel (II) nitrate hexahydrate and aluminium nitrate nonahydrate. The adsorbent was simply synthesized under facile condition via anchoring of Ni/Al-LDH on the pore of melamine sponge (MS). The material was applied for extraction of triazole fungicides prior to HPLC analysis. Under the chosen conditions, the proposed method provides wide linearity between 0.09 –1.00 µg L-1 with coefficients for determination (R2) of greater than 0.99. Low detection limits of 0.03 µg L-1 for all analytes were achieved. The satisfactory recoveries of the real samples at three different concentration levels were obtained in the range of 64.5 % to 105.6 % with RSDs lower than 7.5 %. The findings highlight the importance of developing efficient adsorbents for the enrichment of trace triazoles in surface water, soymilk, honey and egg yolk matrices. Eco-friendliness was confirmed by Analytical Eco-scale and Analytical GREEnness metric (AGREE) which shown that the recommended analytical procedure is more green than previous methods. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks with tunable porous crystallinity and outstanding stability have exhibited fascinating pretreatment performance as ideal extraction media. Herein, the β‐ketoenamine‐linked TpPa‐1 synthesized by 1,3,5‐triformylphloroglucinol and paraphenylenediamine was employed as the absorbent for online micro‐solid phase extraction of trace bisphenols combined with high‐performance liquid chromatography detection. A series of characterizations indicated that the TpPa‐1 possessed large surface areas, high stability, and hydrophobicity. The main experimental parameters affecting the extraction efficiency were optimized in detail. Compared with four commercial sorbents, the TpPa‐1 exhibited superior enrichment capacity for extracting bisphenols. Under the optimum conditions, the established method demonstrated a wide linear range and high sensitivity with the limit of detection ranging from 0.05–0.06 μg/L. Furthermore, the developed method was successfully applied to determine bisphenols in plastic samples. Bisphenol A was actually detected in a transparent box with a concentration of 0.31 μg/g, and the recoveries of the four bisphenols in the plastic samples were 80.5–116% with the relative standard deviation less than 9.2%. Such performance was attributed to recognition affinity, including the π‐π affinity, hydrophobic effect, and hydrogen bond. These results demonstrated that TpPa‐1 possessed great potential to be an excellent pretreatment medium for online separation and analysis of trace analytes in complex samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new nanocomposite (functionalized nanodiamonds@CuAl 2 O 4 @HKUST-1) was synthesized. • Characterization results showed a rough surface with a porous and huge area. • Nanocomposite was used for Cd and Pb extraction from food and water samples. • Low LOD and LOQ were obtained by using the developed method. • Cd and Pb were analyzed via FAAS, without interference from other ions. This study focuses on the development and application of a novel nanocomposite (functionalized nanodiamonds@CuAl 2 O 4 @HKUST-1)-based µ-SPE method for the sensitive and selective extraction of Pb and Cd from food and water samples. The technique offers high sensitivity and selectivity, allowing accurate measurement of these metals at trace levels. The detection limit is 0.031 µg kg−1 for Cd and 0.052 µg kg−1 for Pb, with a relative standard deviation of 1.7 % for Cd and 4.8 % for Pb. The method was successfully applied to real samples and efficiently quantified Pb and Cd in food and natural water samples. The highest concentrations were found in red lentils (0.274 µg kg−1 Pb) and fresh mint (0.197 µg kg −1Cd), but still below recommended limits set by FAO/WHO (300 µg kg−1 for Pb and 200 µg kg−1 for Cd). It promises to ensure food safety, monitor environmental contamination, and informs regulatory decisions to protect public health. [ABSTRACT FROM AUTHOR]

Sepabeads SP70 resin was impregnated with ionic liquid (BMIMPF 6) was used for micro-solid phase extraction of lead(II) prior to its microsampling flame atomic absorption spectrometric determination. The optimum values of experimental parameters such as adsorbent amount, ligand amount, pH, eluent type and concentration, eluent volume, sample volume on recovery of lead were optimized as 5.0 mg, 0.15 mg, 7, HCl, 2 M, 0.4 mL, 50 mL, respectively. The analytical data of the method under optimal condition are as follows; limit of detection (LOD) (3 s/m, N: 10): 0.21 μg L−1, limit of quantification (LOQ) (10 s/m, N: 10): 0.69 μg L−1, preconcentration factor (PF): 125, and relative standard deviation (RSD%): 1.43%. The accuracy of the developed method was checked by addition-recovery tests to real samples and analysis of certified reference materials (Environment Canada TMDA-53.3 (fortified water) and 1570a trace elements in spinach leaves). The recovery values of these analyses are in the range of 90–98%. The method was successfully applied to determination of lead level of food and water samples. [Display omitted] • Sepabeads SP70 was impregnated with ionic liquid for micro-solid phase extraction of lead(II). • Microsampling flame atomic absorption spectrometry was used for lead determination. • Low RSD, LOD and LOQ, high enrichment factor were found. • The method was successfully applied to determination of lead level of food and water sample. [ABSTRACT FROM AUTHOR]

In this work, a bio-composite sorbent, alginate incorporated graphene oxide (Alg/GO) is prepared for the micro solid phase extraction of non-steroidal anti-inflammatory drugs (NSAIDs) from water samples. The sorbent was prepared in a suspended solution form at a ratio of 0.3:1 (w/v %) of graphene oxide (GO) and alginate (Alg). The chemical structure, morphology and surface area of the composite beads were characterized using Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and Brunauer–Emmett–Teller (BET). GO showed good miscibility and well dispersion through intermolecular hydrogen bonds and electrostatic interactions within the Alg matrix. The synthesized sorbent was applied for the determination of the selected drugs in a tap water sample using micro-solid phase extraction technique and was analyzed by high-performance liquid chromatography-ultraviolet detector (HPLC-UV). The results showed good linearity in the range of 10–1000 µg L–1 with correlation coefficients (r ≥ 0.9979), low detection limits (LOD) between 3.1–4.6 µg L–1, excellent relative recoveries in the range of 99.6–102.1% and good reproducibility (RSD ≤ 3.9%). Thus, these validated results showed that Alg/GO could be potential and useful as a bio-composite sorbent for micro-solid phase extraction for the analysis of targeted drugs from aqueous matrices.

This work developed a fast and simple method for the quantification of two important β-agonists, ractopamine (RAC) and clenbuterol (CLEN) in animal urines. The method was based on micro-extraction by a mixed mode monolithic material and analysis by HPLC-UV and UHPLC-Q ExactiveTM Plus Orbitrap mass spectrometer. A mixed functional monolith with nonpolar ester-based structure containing polar carboxylic groups was thermally synthesized in situ in the pipette tips. The material combines both hydrophobic and ionic interactions. Parameters including conditions and composition of reagents for the in-pipette tip monolith synthesis, as well as the extraction process, were investigated and optimized. The procedure for extraction is 800 μL washing solvent of 10:90 (v/v) ACN:water and 150 μL eluting solvent of 30:70 (v/v) ACN:200 mM acetate buffer pH 4.0. Extraction efficiencies of 92% and 100% for RAC and CLEN, respectively, were achieved within 5 min with total organic solvent consumption of 395 μL. The extracts of spiked cattle and swine urines were analyzed by HPLC-UV and UHPLC-Q ExactiveTM Plus Orbitrap mass spectrometer. Good recovery with acceptable precision was observed. The mass spectrometry data confirmed efficient matrix removal by the synthesized extraction sorbent allowing routine analysis by the HPLC-UV method. [ABSTRACT FROM AUTHOR]

A visual, rapid, and sensitive micro‐solid phase extraction method was developed for the detection of p‐hydroxybenzoic acid using molecularly imprinted chitosan microspheres based on deep eutectic solvents, both as a functional monomer and template. The parameters were optimized by using the response surface methodology strategy. The extraction capacity of p‐hydroxybenzoic acid from pear rind under the optimized conditions using response surface methodology was 46.32 mg/g, when the pH of the extract solution (2), extraction time (35 min), extraction temperature (30°C), and adsorbent dosage (2 mg). The molecularly imprinted chitosan microspheres produced higher selectivity and extraction capacity than the traditional materials. [ABSTRACT FROM AUTHOR]

Glucocorticoids have a certain whitening effect on the skin. However, frequent and long‐term use of cosmetics including glucocorticoids is harmful to health. Herein, we proposed a novel micro‐solid phase extraction method for the detection of prednisolone acetate, prednisone, and prednisolone in cosmetics coupled with high‐performance liquid chromatography. In this method, porous monolithic polymer micro‐extraction bars were prepared by "one‐step, one‐pot" in situ photopolymerization combined with sacrificial support in hollow fiber under water atmosphere. The crucial factors such as pH of sample solution, extraction, and elution times that influence micro‐extraction were optimized and found to be 9.0, 2 h, and 32 min, respectively. Under the optimum experimental conditions, the linear range of the calibration curves were from 5.0 to 2000 µg/L with correlation coefficients (R2) between 0.9922 and 0.9996. The limit of detection and limit of quantification were 1.5 µg/L and 5.0 µg/L, respectively, and the recoveries were found to be in range of 69.0–113.3%. The analysis of precision for intraday and interday were less than 10.40 and 10.59%. The device has been successfully achieved photopolymerization under water atmosphere. The results indicated that this method is simple, accurate, and satisfactory for the pretreatment and determination of glucocorticoids in complex cosmetics samples. [ABSTRACT FROM AUTHOR]

Analysis of illegal drugs in biofluids typically requires the incorporation of an adequate sample treatment step together with high performance instrumentation to meet the high demands of the modern Analytical Chemistry in terms of sensitivity and selectivity. Regarding the main objective, sample treatment can be addressed to: i) the extraction of a large number of different compounds; or ii) the selective extraction of one or a reduced group of compounds of similar nature. Traditionally, sample treatment step has been considered the main bottleneck of analytical procedures, consuming most of the required energy, time and resources of the total analysis. The recent advances in the area of materials science and the development of miniaturized sample handling techniques have generated new opportunities hitherto inconceivable. This review article summarizes new developments in sorbent-based techniques for the analysis of illegal drugs in biofluids, providing a critical comparison not only of traditional generic sorbents versus engineered materials, but also the preferred extractive formats for this purpose. [Display omitted] • Generic commercial sorbents are the preferred phases for drug extraction. • Mixed mode interactions are the most employed generic phases. • Molecularly imprinted polymers and aptamers provides excellent selectivity. • The use of miniaturized techniques as μSPE, MEPS and PT-SPE is increasing. [ABSTRACT FROM AUTHOR]

Sulfonamides (SAs) are a class of synthetic antibacterial agents that are diffusely used in the medical industry and animal husbandry. Their prevalence in the influents and effluents of water treatment plants, as well as in rivers and groundwater, has provoked worldwide concern. Monitoring SAs in environmental water is of great significance for public health. However, most of the available detection techniques for SAs are cumbersome and time-consuming. With the increasing number of actual samples, simple, fast and environmentally friendly analytical methods are always in demand. Herein, we describe a highly efficient micro-solid phase extraction (μ-SPE) sample preparation technique based on a novel thiol and ionic liquid bi-functional nanofibers membrane (IL-SH-PAN NFsM) for multi-residue detection of sulfonamides (SAs) in water samples. By the synergistic effect of -SH and -IL, the as-prepared IL-SH-PAN NFsM demonstrated high adsorption capacity and excellent selectivity for SAs. The water samples can be directly used for μ-SPE without pH and ionic strength adjustment, and the eluent can be directly collected for HPLC-MS/MS analysis. Compared with other methods reported in the literature, this method required much shorter extraction time (2 min for a batch), much less amount of adsorbent (4.0 mg) and organic solvent (0.5 mL), while providing much higher sensitivity (1.4–3.9 ng L−1), and fine recoveries (88.8%–117.7%) with relative standard deviations less than 4.26%. A bi-functional nanofibers membrane was prepared for efficient extraction of SAs. The adsorbent exhibited superior adsorption performance and excellent selectivity. The underlying interaction mechanisms derived from -SH and -IL were proposed, which provide a new idea for preparing versatile adsorbents. Rapid, efficient and sensitive detection of SAs in water was achieved. The novel sample preparation technique can be expected as an efficient method for routine trace SAs residue monitoring in various water samples. [Display omitted] • Bi-functional nanofibers membrane was prepared for efficient extraction of SAs. • The adsorbent exhibited superior adsorption performance and excellent selectivity. • Multiple interaction mechanisms derived from SH and IL were proposed. • Rapid, efficient and sensitive detection for SAs in water was achieved. [ABSTRACT FROM AUTHOR]

An environment-friendly and efficient method for simultaneous determination of five alkaloids (nunciferine, O-nornuciferin, liriodenine, armepavine, and pronuciferine) in rat plasma was established by HPLC-MS/MS associated with micro-solid phase extraction (micro-SPE). The plasma sample was pretreated by using micro-SPE columns filled with polymer materials PEP-2 and eluted by little organic solvent (400 µl acetonitrile). The five alkaloids were separated with acetonitrile and 0.1% formic acid aqueous solution on Eclipse plus C18 column. The mode of positive electrospray ionization was used to measure the analytes in multiple-reaction monitoring (MRM). The determination coefficients (R2) of the five alkaloids were greater than 0.99. The lower limit of quantification (LLOQ) of O-nornuciferin, liriodenine, and armepavine was 0.5 ng·ml−1, and that of nunciferine and pronuciferine was 1 ng·ml−1. The validated method was effectively used for the pharmacokinetics of the five orally administrated alkaloids of lotus leaf extract in rat plasma.

The development of sample preparation procedures is still a dynamic process despite a number of already proposed techniques. The main challenge in this research field is to fully replace classical procedures like liquid‐liquid extraction and solid‐phase extraction in gas chromatographic analysis. Some progress has been already achieved for the last 20 years when miniaturized techniques were incorporated in ISO standards. The current review is focused on novel approaches in sample treatment that appeared since 2010. It includes research studies describing non‐conventional instrumental design available to inspire future progress in the field. A combination of a few extraction principles and supporting with additional treatment are the main core suggested for improvement of sample preparation efficiency. This requires good compatibility of extraction media, assessment of multiple experimental parameters, and potential automatization possibilities. [ABSTRACT FROM AUTHOR]

An on-line lab-on-valve system for renewable micro-solid phase extraction coupled with high performance liquid chromatography with photodiode array detection was developed for the determination of hesperidin and diosmin in natural and commercial citrus samples. The method is based on the automatic loading of 8 mL of sample into the C 18 resin, followed by matrix clean-up and elution of the analytes with 0.27 mL of acetonitrile. Next, 0.02 mL of the extract were injected into the chromatographic system. Separation was performed by using a Symmetry® C 18 column (250 × 3.0 mm x 5.0 μm) with a mobile phase consisting in a mixture of methanol, acetonitrile and acidic water (pH = 2.5) in gradient mode at 0.58 mL min−1. The detection wavelength was chosen as 285 nm. Limits of detection, quantification and relative standard deviations were lower than 0.1 μg mL−1, 0.3 μg mL−1 and 4.1%, respectively. Image 1 • Fully automated in-syringe LOV-μSPE procedure for citrus sample pretreatment. • On-line coupling of LOV-μSPE with HPLC-DAD for separation and determination of flavonoids. • Reduced solvent and sample consumptions, time and cost of analysis. • Flavonoids successfully determined in 14 juices from four different citrus fruits. [ABSTRACT FROM AUTHOR]

In this work, magnetic molecularly imprinted polymers (MMIPs) were prepared by the method of co-precipitation polymerization on the surface of vinyl-modified silica magnetic particles. Here, 4-nitrophenol (4-NP) was used as a template and vinylimidazole as a functional monomer. The structural features and morphology of MMIPs were characterized by SEM, FT-IR, TEM and XRD techniques. The results showed that the structures of MMIPs have a layer of silica and MIPs on the surface of the Fe3O4 particles, and they could be rapidly separated from the solution using a magnet. MMIPs possess higher adsorption capacity and excellent selectivity towards template (4-NP) than other structural analogues. And it is found to have good imprinting effect. MMIPs were used as micro-solid phase extraction sorbent for selective separation of 4-NP in lake water sample with high recoveries (90.63–95.63%) and low relative standard deviation values (RSD ≤ 3.2%, n = 3). [ABSTRACT FROM AUTHOR]

An environment-friendly and efficient method for simultaneous determination of five alkaloids (nunciferine, O-nornuciferin, liriodenine, armepavine, and pronuciferine) in rat plasma was established by HPLC-MS/MS associated with micro-solid phase extraction (micro-SPE). The plasma sample was pretreated by using micro-SPE columns filled with polymer materials PEP-2 and eluted by little organic solvent (400 µl acetonitrile). The five alkaloids were separated with acetonitrile and 0.1% formic acid aqueous solution on Eclipse plus C18 column. The mode of positive electrospray ionization was used to measure the analytes in multiple-reaction monitoring (MRM). The determination coefficients (R2) of the five alkaloids were greater than 0.99. The lower limit of quantification (LLOQ) of O-nornuciferin, liriodenine, and armepavine was 0.5 ng·ml−1, and that of nunciferine and pronuciferine was 1 ng·ml−1. The validated method was effectively used for the pharmacokinetics of the five orally administrated alkaloids of lotus leaf extract in rat plasma. [ABSTRACT FROM AUTHOR]

• Synthesized MAGS sorbent and employed for SB-µ-SPE for the first time. • Demonstrated the µ-SPE device is a successful extracting tool for CHCs. • Achieved reproducible results with low detection limits 0.2–2.8 ng mL−1. • SB-µ-SPE-GCMS method was effectively tested for recoveries from milk matrix. In this work, sol-gel reaction chemistry was utilized to create 3-(trimethoxysilyl)propyl methacrylate-poly (propylene glycol) polymer coating on amorphous silica. The synthesized sorbent was characterized using energy dispersive X-ray spectrometry, field emission scanning electron microscopy, and thermogravimetric analysis. The sorbent was then used for membrane protected stir-bar supported micro-solid-phase extraction (SB-µ-SPE) of chlorinated hydrocarbons (CHCs) in milk samples and analyzed using gas chromatography mass spectrometry. Sorbent suitability, sorbent quantity, solvent for desorption, solvent volume, time for extraction, time for desorption, and ionic strength were all optimized for extraction. This method resulted in a wide linear range for all tested CHCs with an r2 up to 0.9992. The lower limits of detection ranged between 0.2 and 2.8 ng mL−1. Reproducibility of the method was also determined at three different concentrations ranging between 3.8 and 7.3%. The relative recoveries in milk samples were found to be between 85.1 and 104.3%. [ABSTRACT FROM AUTHOR]

Highlights • Micro-solid phase extraction is used for detection of antibiotics in milk samples. • Extraction is carried out using graphene oxide–starch–based nanocomposite. • The extracted antibiotics are analyzed by HPLC-UV. • The graphene oxide–starch–based nanocomposite shows high efficiency. • The extractive phase extracts antibiotics without protein precipitation from milk. Abstract In this study, a method was described for the extraction of three antibiotic residues from cow milk samples using a graphene oxide–starch–based nanocomposite. The prepared nanocomposites were employed as an extractive phase for micro-solid phase extraction of antibiotics from cow milk samples. The extracted antibiotics, i.e. amoxicillin, ampicillin and cloxacillin, were subsequently analyzed by high-performance liquid chromatography–ultraviolet detection (HPLC–UV). Important variables associated with the extraction and desorption efficiency were optimized. High extraction efficiencies for the selected antibiotics were conveniently achieved using the starch–based nanocomposite as the extractive phase. The developed method was validated according to the European Commission Decision 2002/657/EC by spiking the selected antibiotics to the blank milk samples. The limits of quantitation (2.7–5.0 μg kg−1) were calculated for the selected penicillin group in milk samples and their quantities are lower than the maximum residue limits (MRLs). The obtained results indicate the remarkable efficiency of the graphene oxide–starch–based nanocomposite performance toward the selected antibiotics. The relative standard deviations of intra and inter–day analysis are less than 3.3 and 6.1%, respectively. Moreover, trueness of method was successfully accomplished via the recovery assays (88–102%) in the fortified blank milk samples with three different concentration levels (MRL, 1.5 MRL and 3 MRL μg kg-1). In overall, the proposed method was a promising alternative for analysis of selected three antibiotics in variety milk samples, due to the effective and easy-to-perform method and acceptable relative recovery in the range 83–105%. [ABSTRACT FROM AUTHOR]

Highlights • LC–MS3 coupled with μ-SPE for the quantitation of triptorelin in rat plasma. • Using MS3 detection to reduce the background noises and matrix interferences to obtain a better S/N ratio at pg/mL level. • The method was successfully applied to pharmacokinetic study of triptorelin in rats. Abstract Triptorelin is a synthetic decapeptide used for the treatment of prostate cancer. Attempts to determine triptorelin in clinical use by liquid chromatography-tandem mass spectrometry with multiple reaction monitoring have encountered problems due to its low concentration in plasma (pg/mL) and interference from endogenous peptides. We have overcome these issues using micro-solid phase extraction (μ-SPE) on Oasis® HLB 96-well μElution plates followed by LC–MS3. Sample preparation by μ-SPE achieved sample concentration without the need for evaporation and reconstitution steps. Detection by LC–MS3 showed no significant matrix interference at the retention time of analyte and achieved high sensitivity (lower limit of quantitation 10 pg/mL) and good linearity in the range 10–3000 pg/mL. The method was successfully applied to a pharmacokinetic study in rat involving a single intramuscular injection of a formulation of triptorelin acetate biodegradable microspheres. [ABSTRACT FROM AUTHOR]

A new, sensitive and fast dispersive liquid-liquid microextraction (DLLME) coupled with micro-solid phase extraction (μ-SPE) was developed for determination of zearalenone (ZEN) in wheat samples. The DLLME was performed using acetonitrile/water (80:20 v/v) as the disperser solvent and 1-octanol as the extracting solvent. The acetonitrile/water (80:20 v/v) solvent was also used to extract ZEN from solid wheat matrix, and was directly applied as the disperser solvent for DLLME process. Additionally, hydrophobic oleic-acid-modified magnetic nanoparticles were used in μ-SPE approach to retrieve the analyte from the DLLME step. So, the method uses high surface area and strong magnetism properties of these nanoparticles to avoid time-consuming column-passing processes in traditional SPE. Main parameters affecting the extraction efficiency and signal enhancement were investigated and optimized. Under the optimum conditions, the calibration curve showed a good linearity in the range of 0.1-500 μg kg−1 (R2=0.9996) with low detection limit of 83 ng g−1. The intra-day and inter-day precisions (as RSD %) in the range of 2.6-4.3 % and high recoveries ranging from 91.6 to 99.1 % were obtained. The pre-concentration factor was 3. The method is simple, inexpensive, accurate and remarkably free from interference effects.

Dispersive microextraction techniques are key in the analytical sample treatment context as they combine a favored thermodynamics and kinetics isolation of the target analytes from the sample matrix. The dispersion of the extractant in the form of tiny particles or drops, depending on the technique, into the sample enlarges the contact surface area between phases, thus enhancing the mass transference. This dispersion can be achieved by applying external energy sources, the use of chemicals, or the combination of both strategies. Effervescence-assisted microextraction emerged in 2011 as a new alternative in this context. The technique uses in situ-generated carbon dioxide as the disperser, and it has been successfully applied in the solid-phase and liquid-phase microextraction fields. This minireview explains the main fundamentals of the technique, its potential and the main developments reported.

This article reviews the synthesis and uses of nanoparticle-based hybrid monoliths in microextraction techniques. Synthesizing monolithic solids containing nanoparticles allows the advantages of the two sorbent phases to be synergistically combined. The resulting hybrid material exhibits outstanding capabilities for isolating the target compounds from the samples. In addition to conventional in-cartridge solid-phase extraction, the monoliths can be easily adapted for use in most of the usual formats of micro-solid phase extraction including capillaries, pipette tips, spin columns, microfluidic chips and stirred units. The most salient uses devised so far are described and critically discussed in this article, which deals with both silica and organic monolithic solids modified with nanostructured materials including carbonaceous and metal or metal oxide nanoparticles. [ABSTRACT FROM AUTHOR]

Highlights • Glyoxal and methylglyoxal in atmospheric fine particulate matter were determined. • VA-μ-SPE using C18 sorbent followed by LC-DAD was carried out. • On-sorbent derivatization by 2,4-DNPH and extraction was performed in one step. • The procedure showed good extraction efficiency for these two analytes. Abstract Determination of α-dicarbonyl compounds, glyoxal (Gly) and methyl glyoxal (Mgly), in atmospheric fine particulate matter PM 2.5 (particulate matter with an aerodynamic diameter of less than 2.5 μm) which play vital roles in generating secondary organic aerosols in the ambient air, was carried out by vortex-assisted micro-solid phase extraction (VA-μ-SPE)˗liquid chromatography-diode array detection (LC-DAD), with on-sorbent derivatization by 2,4-dinitrophenylhydrazine (DNPH). This is the first time such an approach of combining on-sorbent derivatization and extraction in one step together with LC analysis has been applied to PM 2.5. Extraction parameters such as selection of sorbent, extraction time, desorption time and sample volume were optimized using water samples spiked with Gly and Mgly. Under the most favourable conditions, good intra- (1.39%–2.78%) and inter-day (2.29%–6.56%) precision and linearity (ranging between 0.5 and 100 ng mL−1) along with coefficients of determination 0.998 and 0.997, were determined. The limits of detection were determined to be 0.14 ng mL−1 (derivatized Gly) and 0.15 ng mL−1 (derivatized Mgly) whereas the limits of quantification were 0.47 ng mL−1 and 0.50 ng mL−1, respectively. The developed method was successfully employed to the determination of Gly and Mgly associated with PM 2.5. The latter was collected on glass fiber filters which were immersed in methanol: water (1:1 v/v) for μ-SPE, which was conducted using a sorbent pre-coated with DNPH. The concentrations of the Gly and Mgly were determined to be 0.38 ng m−3 and 0.41 ng m−3 in the sampled ambient air, with relative recoveries of between 69–97%. [ABSTRACT FROM AUTHOR]

In the present study, electrospun polyethylene terephthalate nanofibers doped with graphene oxide nanoparticles (GO-PET) was fabricated and used as an effective adsorbent in micro-solid phase extraction (μ-SPE) of tetracycline (TC) and cefotaxime (CF) from honey samples prior to HPLC. The UV–vis spectrophotometer was utilized in the optimization step. The adsorbent was fully characterized using SEM, FT-IR, BET, and BJH methods. The specific surface area and average pore size of the adsorbent were 79.5 m 2  g −1 and 4.83 nm, respectively. The honey samples were dissolved in water (5% w / v ) at 50 °C for 10 min, centrifuged at 4000 rpm for 15 min and finally filtered using a filter paper before performing the extraction. The important factors of the method were studied to obtain the optimal conditions. Under the optimum conditions (sample solution, 100 mL; adsorbent, 40 mg; pH 5; extraction time, 10 min; desorption solvent; MeOH, 200 μL), the limits of detection for TC and CF were 15.3 and 3.0 μg kg −1 . The linear dynamic range (LDR) was obtained as 10–5000 μg kg −1 with the determination coefficients (R 2 ) of 0.9939 and 0.9959, respectively. The real sample extraction recoveries were 89–94% and 95–98% for TC and CF, respectively. The intra-day and inter-day precisions were 5.6 and 4.9% (n = 3) for TC, and 3.6 and 4.5% (n = 9) for CF. [ABSTRACT FROM AUTHOR]

Sorbents were prepared by cross-linking β-cyclodextrin (β-CD) using two different types of cross-linker units at variable reactant mole ratios. The resulting polymers containing β-CD were evaluated as sorbents in micro-solid phase extraction (μ-SPE) format for the extraction of the endogenous steroids testosterone (T), epitestosterone (E), androsterone (A), etiocholanolone (Etio), 5α-androstane-3α,17β-diol (5αAdiol) and 5β-androstane-3α,17β-diol (5βAdiol). The best sorbent (C1; cyclodextrin polymer) showed superior extraction characteristics compared with commercial sorbents (C18 and Bond Elut Plexa). Parameters influencing the extraction efficiency of the C1 sorbent such as extraction and desorption times, desorption solvent and volume of sample were investigated. The extracts were separated using a Hypersil Gold column (50 × 2.1 mm, 1.9 μm) under gradient elution coupled to a LC–MS/MS. The compounds were successfully separated within 8 min. The method offers good repeatability (RSD < 10%) and linearity (r 2  > 0.995) were within the range of 1–200 ng mL −1 for T and E, 250–4000 ng mL −1 for A and Etio and 25–500 ng mL −1 for 5αAdiol and 5βAdiol, respectively. The method was applied for the determination of steroid profile of urine from volunteers. [ABSTRACT FROM AUTHOR]

• (Semi) automated solid-based extraction methods have been described. • On-line coupling of packed sorbent SPME methods to analytical instruments were reviewed. • Automated and semi-automated analytical methods concerning SPME have been reviewed. • Combination of 3D printing and robotic platforms with (semi)automated methods has been investigated as the future trend. • Automated packed sorbent extractions and their applications for pollutants extraction have been reviewed. In this study, the packed sorbent solid phase (micro) extraction methods from manual to automated modes are reviewed. The automatic methods have several remarkable advantages such as high sample throughput, reproducibility, sensitivity, and extraction efficiency. These methods include solid-phase extraction, pipette tip micro-solid phase extraction, microextraction by packed sorbent, in-tip solid phase microextraction, in-tube solid phase microextraction, lab-on-a-chip, and lab-on-a-valve. The recent application of these methods for the extraction of organic and inorganic compounds are discussed. Also, the combination of novel technologies (3D printing and robotic platforms) with the (semi)automated methods are investigated as the future trend. [ABSTRACT FROM AUTHOR]

In the present work, molecularly imprinted polymer (MIP) microspheres were packed in polypropylene hollow fiber (HF) segments for the micro solid-phase extraction and clean-up of thiabendazole (TBZ) in citrus samples. Experimental parameters affecting TBZ extraction were carefully optimized. Hollow fiber membrane was able to protect MIP beads from solid matrix allowing the extraction and clean-up without the inclusion of further filtration and/or centrifugation steps. Under optimum experimental conditions, recoveries for TBZ at 0.83 mg kg −1 concentration level ranged from 5.1 to 6.1%, depending upon the sample analyzed (orange or lemon peel samples), with relative standard deviations (RSDs) lower than 4%. The limits of detection were 0.004 mg kg −1 in orange and 0.009 mg kg −1 in lemon, low enough for the determination of TBZ according to European Union legislation. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs), composed of metal ions and organic connector, are a new group of novel porous materials. In light of their advantageous features (e.g., high porosity, uniform cavities, good thermal stability, and high surface area), this class of materials has recently attracted a great amount of attention in analytical chemistry. This review mainly focuses on the up-to-date information on the analytical applications of MOFs as novel adsorbent materials. To this end, we compiled and reviewed all available data for the extraction and separation of diverse organic and inorganic pollutants from a variety of samples representing environmental, food, and biological media. [ABSTRACT FROM AUTHOR]

Water-insoluble β-cyclodextrin polymer was synthesized by chemical cross-linking using epichlorohydrin (EPI) as a cross-linker agent. The produced water-insoluble polymer was used as a sorbent for the micro-solid phase extraction (μ-SPE) of benzene, toluene, ethylbenzene and xylenes (BTEX) from water samples. The μ-SPE device consisted of a sealed tea bag envelope containing 15 mg of sorbent. For the evaluation of the extraction efficiency, parameters such as extraction and desorption time, desorption solvent and salt concentration were investigated. At an extraction time of 30 min in the course of the extraction process, analytes were extracted from a 10 mL aqueous sample solution. The analytes were desorbed by ultrasonication in 200 μL of acetonitrile for 20 min. Analysis of the analytes was done by a gas chromatography-flame ionization detector (GC–FID) system. The enrichment factor (EF) was found to be in the range 23.0–45.4 (EF max = 50.0). The method provided linearity ranges of between 0.5 and 500.0 ng/mL (depending on the analytes), with good coefficients of determination (r 2 ) ranging between 0.997 and 0.999 under optimized conditions. Detection limits for BTEX were in the range of between 0.15 and 0.60 ng/mL, while corresponding recoveries were in the range of 46.0–90.0%. The relative standard deviation of the method for the analytes at 100.0 ng/mL concentration level ranged from 5.5 to 11.2% (n = 5). The proposed method was concluded to be a cost effective and environmentally-friendly extraction technique with ease of operation and minimal usage of organic solvent. [ABSTRACT FROM AUTHOR]

Amphetamine selective molecularly imprinted sol-gel polymer tablets, MIP-tablets, for solid-phase microextraction of biofluid samples were prepared. An acetonitrile solution of deuterated amphetamine template and silane precursor, 3-(propylmethacrylate) trimethoxysilane, was soaked into the pores of polyethylene tablet substrates and polymerized by an acid-catalysed sol-gel process. Application of the resultant MIP-tablets to extract amphetamine from human urine samples followed by LC–MS/MS analysis was investigated. The extraction protocol was optimised with respect to pH of sample, addition of sodium chloride, extraction time, desorption solvent and desorption time. The final analysis method determined amphetamine in human urine with a limit of detection (LOD) of 1.0 ng/mL and a lower limit of quantification (LLOQ) of 5 ng/mL. Validation demonstrated accuracy of the method was 91.0–104.0% and inter-assay precision was 4.8–8.5% (RSD). Extraction recovery was 80%. The MIP-tablets could be re-used and the same tablet could be employed for more than twenty extractions. [ABSTRACT FROM AUTHOR]

Agarose-chitosan-immobilized octadecylsilyl-silica (C 18 ) film micro-solid phase extraction (μSPE) was developed and applied for the determination of phenanthrene (PHE) and pyrene (PYR) in chrysanthemum tea samples using high performance liquid chromatography-ultraviolet detection (HPLC-UV). The film of blended agarose and chitosan allows good dispersion of C 18 , prevents the leaching of C 18 during application and enhances the film mechanical stability. Important μSPE parameters were optimized including amount of sorbent loading, extraction time, desorption solvent and desorption time. The matrix match calibration curves showed good linearity ( r ⩾ 0.994) over a concentration range of 1–500 ppb. Under the optimized conditions, the proposed method showed good limits of detection (0.549–0.673 ppb), good analyte recoveries (100.8–105.99%) and good reproducibilities (RSDs ⩽ 13.53%, n = 3) with preconcentration factors of 4 and 72 for PHE and PYR, respectively. [ABSTRACT FROM AUTHOR]

In the present work molecularly imprinted sol-gel tablet (MIP-Tablet) was prepared. The MIP-sol-gel was prepared as a thin layer on polyethylene material in a tablet form. Methadone-d 9 was selected as the template and 3-(propylmethacrylate)-trimethoxysilane was used as precursor. MIP-Tablet was applied for micro-solid phase extraction (μ-SPE). The MIP-Tablet was used for the determination of methadone in human plasma samples utilizing liquid chromatography-tandem mass spectrometry; and each tablet could be used twenty times. The extraction time was 10 min while desorption time was 6 min. Factors affecting the extraction efficiency such as desorption solvents, sample pH, salt addition, extraction time, desorption time and adsorption capacity were investigated. The calibration curves were obtained within the range of 5–5000 ng/mL using methadone in human plasma samples. The coefficients of determination (r 2 ) values were ≥0.999 for all runs and the extraction recovery was >80%. The accuracy values for quality control samples varied from +3.6 to +9.7% and the inter-day precision (RSD %) values were ranged from 5.0 to 8.0%. The limit of detection was 1.0 ng/mL and the lower limit of quantification was 5 ng/mL utilizing methadone in human plasma samples. [ABSTRACT FROM AUTHOR]

A method of analyzing environmental contaminants in water based on micro-solid phase extraction (μ-SPE) followed by thermal extraction (TE) and a cold-trapping step, coupled with gas chromatography-mass selective detection (GC–MSD) was developed and validated. μ-SPE–TE– GC–MSD was employed in the determination of five polybrominated diphenyl ethers. The μ-SPE sorbent was chitosan-graphene oxide (CS-GO) composite, which was prepared by mixing CS and GO by means of ultrasonication. The CS in the composite was cross-linked with glutaraldehyde. After μ-SPE, the analytes in the extract were extracted thermally in a thermal desorption unit tube combined with a cooled injection system, coupled to GC–MSD. The extraction conditions were optimized for the detection of the target compounds in water. This method provided linearity ranges of between 0.1 and 20 μg L −1 (depending on the analytes), with coefficients of determination, r 2 , ≥0.9982. The calculated relative recoveries were between 71.52 and 96.15% whereas precision (based on % relative standard deviations) was between 3.54 and 11.36%. The method showed limit of detection and limit of quantification ranges of between 0.007 and 0.016 μg L −1 , and between 0.023 and 0.054 μg L −1 , for the two groups of analytes, respectively. The method was applied to the determination of the target analytes in water. [ABSTRACT FROM AUTHOR]

Chitosan (CS) microspheres were synthesized by the precipitation method and cross-linked with glutaraldehyde. The cross-linked CS microspheres (20 mg) were used as sorbents for the micro-solid phase extraction (µ-SPE) of benzene, toluene, ethylbenzene, xylenes and styrene (BTEX-S) from water. The µ-SPE device consisted of a sealed polypropylene envelope housing the microspheres for the evaluation of the extraction efficiency. Analysis was by gas chromatography-mass spectrometry (GC-MS). Under the optimized conditions, the method provided linearity range of between 0.5 and 50 μg L-1 with good correlation coefficients of between 0.985 and 0.998. The relative standard deviations of μ-SPE coupled with GC-MS were found to be between 2 and 3%. Method detection limits for BTEX-S were in the range of between 0.01 and 0.04 μg L-1 while the relative recoveries were in the range of between 59 and 97%. The proposed method is a cost effective, fast and environmentally friendly extraction technique with ease of operation and minimal usage of organic solvent. [ABSTRACT FROM AUTHOR]

In this work, novel molecularly imprinted polymer-coated hollow fibers (MIP-HFs) have been prepared and evaluated for the development of a micro-solid phase extraction method for the analysis of triazines in aqueous samples using high performance liquid chromatography and UV detection. The proposed extraction method combines liquid-liquid microextraction and molecular imprinting technology. In brief, a thin film of toluene is immobilised in the pores of the obtained MIP-HF. Afterwards, the conditioned MIP-HF is immersed in the water sample. Under stirring for a certain time, the target analytes are liquid-liquid extracted from the sample to the immobilised toluene and then these diffuse to the specific binding sites of the MIP. The effect of various experimental parameters as time and stirring-rate and salting-out effect among others, were studied for the establishment of optimum rebinding conditions. Recoveries for seven triazines tested in 100 mL pure water samples spiked with 15 μg L −1 of each triazine were within 0.8–6.9%, with a relative standard deviation (RSD) < 10% (n = 3). The detection limits (LODs) were within 0.05–0.1 μg L −1 , depending upon the triazine. The proposed methodology was successfully applied to extract the triazines from spiked tap and river water samples at μg L −1 concentration level. The mircroextraction procedure with the developed MIP-HFs overcomes the typical low performance and lack of selective recognition of MIPs in aqueous media, allowing the determination of triazines in environmental waters at expected real concentration levels. [ABSTRACT FROM AUTHOR]

Micro-solid phase extraction (μ-SPE), with liquid chromatography-tandem mass spectrometry has been developed for the determination of trace levels of perfluorinated carboxylic acids (PFCAs) in human plasma. The μ-SPE sorbent was surfactant-templated mesoporous silica. Extraction time, desorption time and salt concentration were chosen as the most effective parameters and were optimized simultaneously by use of central composite design. Under the optimized extraction conditions, good linearity in the range of 100 and 5000 ngL −1 was obtained with coefficients of determination of between 0.986 and 0.995. The limits of detection (at a signal to noise ratio of 3) were measured to be in the range of between 21.23 and 65.07 ngL −1 , and limits of quantification (at a signal to noise ratio of 10) were in the range of between 70.77 and 216.92 ngL −1 . The relative recoveries of spiked PFCAs in different samples were in the range of between 87.58 and 102.45%. As expected from the global distribution of PFCs, contaminations at low levels (less than 200 ngL −1 ) were detected (with the highest concentration recorded for perfluorooctanoic acid (PFOA)). Considering the complex nature of biological samples and the issue of matrix effects in the analysis of PFCAs, μ-SPE as an extraction method was shown to be advantageous; it combined extraction and concentration in one single step with no additional sample clean-up, and was able to remove significant matrix interferences. [ABSTRACT FROM AUTHOR]

In this work, a novel methodology based on the combination of MIP technology with micro solid-phase extraction in a hollow fibre device for the trace enrichment and cleanup of triazines in environmental waters is described. All parameters affecting both migration of triazines from samples to the lumen of the fibre and rebinding into MIP sites have been carefully optimized. Final conditions included, addition of 20% NaCl to the sample to produce salting-out effect, extraction of analytes during 45 min with orbital stirring at 750 rpm, and then washing the fibre with toluene during 5 min to allow selective recognition of triazines before elution in HPLC inserts containing 450 μL of a methanol/acetic acid mixture (95/5, v/v). Under optimum conditions, quantitative recoveries for simazine, cyanazine, atrazine, propazine and terbutylazine, were achieved both in surface, ground and tap water samples, with relative standard deviations lower than 10.6%, and limits of detection in the low ng L −1 concentration level. [ABSTRACT FROM AUTHOR]

In this work, a combination of molecularly imprinted polymer (MIP) technology with micro solid-phase extraction in a hollow fibre device is described. MIP microspheres were synthesized and packed into polypropylene hollow fibre (HF) segments. The proposed device was used directly for trace enrichment and clean-up of triazines in soil sample extracts by hollow-fibre membrane-protected molecularly imprinted micro solid-phase extraction (HFM-protected-MI-MSPE). Analytes were extracted from soil by ultrasonic assisted extraction, evaporated to dryness and reconstituted in toluene. The proposed device was immersed in the toluene extracts, and migrations of analytes through the walls of the hollow fibre was achieved with the help of external agitation. Then, selective recognition of the target analytes by MIP-microspheres took place in the inner part of the HF. All parameters affecting the extraction were optimized. Under optimum conditions, quantitative recoveries were obtained for simazine, cyanazine, atrazine, propazine and terbutylazine in soil samples, with relative standard deviations lower than 11%. The detection limits (LODs) were lower than 5 ng g−1 in all cases.

A facile method of extraction using porous membrane protected micro-solid phase extraction (μ-SPE) with a graphene-based sorbent followed by high performance liquid chromatography-ultraviolet detector was developed. The reduced graphene oxide (r-GO) (1 mg), synthesized from graphite oxide, was enclosed in a polypropylene bag representing the μ-SPE device, which was used for the extraction of estrogens such as estrone, 17β-estradiol, 17α-ethynylestradiol and diethylstilbestrol in water. The r-GO obtained was identified and characterized by Fourier transform infrared, transmission electron microscopy, scanning electron microscopy and thermogravimetric analysis. The sorbent was loaded with sodium dodecyl sulfate by sonication to prevent agglomeration in aqueous solution. With this method, low limits of detection of between 0.24 and 0.52 ng L-1 were achieved. For estrogen analysis a linear calibration range of 0.01-100 μg L-1 was obtained, with the coefficients of determination (r2) higher than 0.992. This proposed method was successfully applied to determine estrogens in water. [ABSTRACT FROM AUTHOR]

We describe a novel solid phase sorbent that was synthesized by coupling graphene oxide (GO) to ethylenediamine (EDA). This nanomaterial (referred to as GO-EDA) is capable of adsorbing the ions of iron, cobalt, nickel, copper, zinc and lead. The ethylenediamine-modified graphene oxide was characterized by X-ray photoelectron spectroscopy, scanning electron microscopy and Fourier transform infrared spectroscopy. The analytical procedure relies on (a) sorption of metal ions on GO-EDA dispersed in aqueous samples; (b) filtering, and (c) direct submission of the filter paper to energy-dispersive X-ray fluorescence spectrometry. This kind of dispersive micro-solid phase extraction was optimized with respect to pH values, concentration of GO-EDA, contact time, and the effects of interfering ions and humic acid on recovery of determined elements. Under optimized conditions, the recoveries of spiked samples range from 90 to 98 %. The detection limits are 0.07, 0.10, 0.07, 0.08, 0.06 and 0.10 ng mL for Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Pb(II), respectively. The method has a relative standard deviation of <6 %, and its accuracy was verified by analysis of two standard reference materials [LGC6016 (estuarine water) and BCR-610 (groundwater)]. It was successfully applied to the determination of trace amounts of these metal ions in water samples. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Porous membrane-protected micro-solid phase extraction (μ-SPE) using a molecularly imprinted polymer (MIP) as an adsorbent has been proposed as an integrated extraction-cleanup procedure for isolating cocaine (COC) and its metabolites [benzoylecgonine (BZE), ecgonine methyl ester (EME), and cocaethylene (CE)] from human urine. MIP beads have been synthesized using COC as a template molecule, ethylene dimethacrylate (EDMA) as a functional monomer, divinylbenzene (DVB) as a cross-linker, and 2,2′-azobisisobutyronitrile (AIBN) as an initiator. High performance liquid chromatography – tandem mass spectrometry (HPLC-MS/MS) has been used for quantifying the analytes after MIP-μ-SPE. Variables such as urine pH, adsorption temperature and time, mechanical (orbital-horizontal) stirring; and composition of the eluting solution and eluting time, were evaluated. The proposed method was shown to be precise and accurate [relative standard deviations (RSDs) of intra- and inter-day tests ranging from 3 to 8% and from 2 to 10%, respectively]; and analytical recoveries in the range of 89–100%). In addition, excellent accuracy was also verified after analyzing a FDT +25% control material for BZE. The detection limits were in the range of 0.16–1.7 ng L −1 , low enough for confirmative conclusions regarding cocaine abuse. The method was finally applied for screening/quantifying cocaine and metabolites in urine samples from poly-drug abusers. [ABSTRACT FROM AUTHOR]