Selective Solid-phase Extraction Research Articles

Selective solid phase extraction of folic acid from tomato as a biological source with a magnetic molecularly imprinted polymer measured by fluorescence spectroscopy

AbstractA novel magnetic molecular-imprinted polymer (MMIP) was used to selectively extract folic acid directly from real samples. Folic acid was used as template molecule, Fe3O4/SiO2-3-triethoxysilyl-propyl-acrylamide as functional monomer, azobisisobutyronitrile as initiation, ethylene glycol dimethacrylate as crosslinker agent, and acrylamide as the secondary monomer in a mixed ethanol-water solvent. The effect of different parameters on the extraction efficiency was studied, and the optimum conditions were established as follows: the concentrations of crosslinking and template were fixed at 0.05 and 0.06 g, absorption percentage was 96.5, pH was adjusted to 8, and extraction time was 8 h with a temperature of 25 °C. By examining the effect of pH, we tried to investigate the effect of the amide groups that present in MMIP and its intermolecular hydrogen interaction with folic acid. After optimising the effective parameters in polymer synthesis and adsorption rate, a magnetic imprinting dispersive solid-phase extraction method combined with fluorescence spectrophotometry at λem = 367 nm (MMIP-DSPE-FL) was constructed for sensitive determination of folic acid in tomato samples. The limit of quantification (LOQ) and limit of detection (LOD) values were 30.00 ± 0.01 μg L−1 and 10.00 ± 0.03 μg L−1, respectively, after the MMIP-DSPE preconcentration. Three tomato samples were analysed to give recoveries in the range of 80.2–81.6%, with relative standard deviation values below 0.6% (n = 3). The prepared MMIP-DSPE showed high selectivity toward folic acid, which could be used six times without changing adsorption capacity. The adsorption isotherm of the folic acid-imprinted polymer pursued the Langmuir model (RL = 0.029), and the kinetics model followed pseudo-first-order (R2 = 0.9974).

Novel phenazine-based microporous organic network for selective and sensitive determination of trace sulfonamides in milk samples

BackgroundSulfonamide (SA) residues in food of animal origin possess a potential threat to human health and environment. However, due to the polar and ionic characteristics and trace level of SAs and the complexity of food matrices, direct measurement of SAs in these samples is still very difficult. Development of efficient sample pretreatment method for sensitive and selective extraction of trace SAs is of great significance and urgently desired. Therefore, rational design and synthesizing advanced and selective extractants is quite important. ResultsIn this work, a novel phenazine-based microporous organic network (MON) named TEPM-DP is reasonably synthesized and employed as a packing material for selective solid phase extraction (SPE) and sensitive determination of four typical SAs in milk samples. Phenazine-based monomer with aromatic and heteroaromatic ring and numerous N atoms is chosen to construct TEPM-DP adsorbent to provide π-π, hydrogen bonding, hydrophobic, and electrostatic extraction sites for SAs. The proposed method owns wide linear ranges, low limits of detection, high enrichment factors, and good precisions and recoveries for SAs in complex milk samples. The recoveries of SAs on TEPM-DP are much higher than those of commercial C18 and activated carbon. The extraction mechanisms are also elucidated via FT-IR, XPS, and comparative experiments. SignificanceThis work reports the first example of design and synthesizing phenazine-based MON in SPE via a simple and rapid solvothermal method. The results reveal the great prospects of TEPM-DP for enriching polar and ionic SAs in complex samples and uncover the potency of phenazine-based MON in sample pretreatment, which will promote the development of MON.

Novel polyvinyl alcohol/gum tragacanth molecularly imprinted-electrospun nanofibers as adsorbent for selective solid phase extraction of bisphenol A

A polyvinyl alcohol/gum tragacanth molecularly imprinted nanofiber fabricated by electrospinning (PVA/GT-MIN) was used as an efficient adsorbent for the solid phase extraction (SPE) of bisphenol A (BPA) in water samples. PVA and GT were functional polymers and BPA was the template for molecular imprinting. BPA was bound to the polymer matrix through hydrogen bonding. The SEM image of PVA/GT-MIN demonstrated a rough morphology with pores and a diameter of 501 nm. The data for the adsorption of BPA on PVA/GT-MIN fitted the Freundlich isotherm and pseudo-second-order kinetics models. The proposed SPE using PVA/GT-MIN coupled with high performance liquid chromatography-diode array detection presented good linearity from 50 μg/L–5 mg/L (R2 = 0.9999) and yielded a limit of detection of 21 μg/L. The PVA/GT-MIN was applied to extract bottled water for BPA analysis and recoveries were 93.1–97.7 % (RSDs ≤ 3.6 %). This study presents a novel, easily prepared PVA/GT-MIN adsorbent for the extraction of BPA in water.

Development of a Molecularly Imprinted Polymer for Determination of Atenolol Based on Selective Solid Phase Extraction and Application in Pharmaceutical Samples

This paper demonstrates the synthesis and storage of molecular-imprinted polymers (MIP) at room temperature using bulk polymerization of atenolol (Ate), which is characterized by high sensitivity, low costs, and high stability. The research used 0.99:6:20 mmol ratios of template, monomer, and cross-linking agents for the polymerization in order to ensure an appropriate adsorption capacity. By making MIP for atenolol as Ate-MIP, which could be looked at with a UV-VIS spectrophotometer at 276 nm, Fourier- transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM), a functional monomer of allyl chloride with cross-linking ethylene glycol dimethyl acrylate was made. Mass spectrometric (MS) detection may use allyl chloride to determine atenolol levels in pharmaceutical preparations. The GC/MS methods developed in this study are accurate, sensitive, and precise and can be easily applied to (NOVATEN/India and ATENOIOI/U.K.) tablets in pharmaceutical preparation. The elution process was applied to the template (Ate) from the Ate-MIP, which developed cavities, caused by using porogenic solutions of methanol, chloroform, and acetic acid (70:20:10, respectively). The maximum adsorption capacity of Ate-MIP was 2.9957 µmol/g, and the ratio of template to monomer was 1:1 in adherence to the Langmuir isotherm model. A solid-phase extraction (SPE) syringe packed with molecular imprinted polymers (MIPs) was used to selectively separate and pre-concentrate Ate from aqueous solutions and estimations of atenolol.

Fabrication of fluorinated magnetic microporous organic network for selective and efficient extraction of benzoylurea insecticides in tea beverages

In this work, a novel fluorinated magnetic microporous organic network (Fe3O4@FMON) was exquisitely designed and synthesized for highly efficient and selective magnetic solid phase extraction (MSPE) of fluorinated benzoylurea insecticides (BUs) from complex tea beverage samples. The Fe3O4@FMON exhibited good extraction for BUs via the pre-designed hydrophobic, π-π stacking, hydrogen bonding and specific FF interactions. A sensitive Fe3O4@FMON-based MSPE-HPLC-UV method with wide linear range (0.10–1000 μg L−1, R2 ≥ 0.996), low limits of detection (0.01–0.02 μg L−1), and large enrichment factors (85.6–98.0) for BUs from tea beverage samples was developed. By decorating F elements within MON's networks, the Fe3O4@FMON characterized good hydrophobicity and chemical stability, which could be reused at least 8 times without decrease of recoveries. This work demonstrated the great prospects of Fe3O4@FMON for enriching trace BUs from complex substrates and triggered the potential of FMON for sample pretreatment of fluorinated analytes.

Selective solid phase extraction of phototoxic furanocoumarins using molecularly imprinted polymers

Furanocoumarins are secondary plant metabolites found in citrus plants. Essential oils from these plants are widely used in cosmetic products. They have attracted attention for their phototoxicity, which can even lead to skin burns. Therefore, the furanocoumarin concentration is controlled by the European Union according to Regulation (EC) No. 1223/2009, where a limit of 1 mg kg−1 is specified in sun protection and bronzing agents. This study describes the synthesis of two molecularly imprinted polymers (methacrylamide and methacrylic acid as monomers) as novel materials for solid phase extraction. After optimisation of the extraction protocol, both polymers gave satisfying recovery results for a furanocoumarin standard mixture containing the six markers proposed by the International Fragrance Association (IFRA). Furthermore, spiked sun oil samples were extracted using an adapted extraction protocol. Since the studies showed promising results including 75–149 % recovery and 100 % loading efficiency for the methacrylic acid polymer, a validation of the analytical method was performed. Analysis was performed using HPLC-MS/MS in high specificity multi-reaction monitoring mode. The validation showed acceptable results for most parameters. In addition, a comparison with commercially available Strata-X cartridges was completed, revealing superior recovery performance of the molecularly imprinted polymer. In conclusion, molecularly imprinted polymers represent a novel and efficient method for selective solid-phase extraction of phototoxic furanocoumarins.

SYNTHESIS OF TETRACYCLINE IMPRINTED POLYMERS WITH METHACRYLIC ACID AS FUNCTIONAL MONOMER IN METHANOL-CHLOROFORM MIXTURE USING BULK AND PRECIPITATION POLYMERIZATION METHOD

The content of tetracycline residues in poultry meat products can cause antibiotic resistance in humans who consume these products, so it is necessary to develop sensitive analytical techniques to determine the levels of tetracycline residues to assess the safety of these products for consumption. The molecular imprinting technique is a method to produce sorbents with molecular recognition capability of target compounds that can be used to increase the selectivity of solid phase extraction to extract tetracycline residues for further analysis. This study aimed to obtain a sorbent synthesized by molecular imprinting technique to analyze tetracycline in poultry meat products. The stages of the research began with the study of the interaction of functional monomers with template molecules, determining the association constants of functional monomers with template molecules, synthesis of imprinted polymer molecules using bulk and precipitation methods, evaluating the ability and adsorption capacity of the synthesized polymers, assess the selectivity of polymers for analog structures and physical characteristics with FTIR. The research showed that methacrylic acid was the best functional monomer with a binding energy value of -27.3776 kcal/mol. The higher adsorption capacity was achieved by Molecularly Imprinted Polymer (MIP) that was synthesized by precipitation method (MIP2) than the other MIP synthesized by bulk polymerization (MIP1) with a value of 0.8748 mg/g and 0.4077 mg/g, respectively. The analogous compounds' imprinting factor values for each MIP were 1.197 and 1.1272. The polymer synthesized by molecular imprinting technique is selective for extracting and analyzing tetracycline from poultry meat matrix.

ПРИМЕНЕНИЕ СОРБЕНТА ДЛЯ ТВЕРДОФАЗНОЙ ЭКСТРАКЦИИ НА ОСНОВЕ ГИПРОМЕЛЛОЗЫ ДЛЯ КОЛИЧЕСТВЕННОГО ОПРЕДЕЛЕНИЯ КИСЛОТЫ САЛИЦИЛОВОЙ В КОМБИНИРОВАННЫХ ЛЕКАРСТВЕННЫХ ПРЕПАРАТАХ

Introduction. In quality control of pharmaceutical formulations, there are methodological approaches based on the preliminary separation of sample components and approaches without preliminary separation. The use of solid-phase extraction (SPE) allows to separate analytes during sample preparation, with the separation selectivity determining the analysis selectivity as a whole. Currently, sorbents that provide selectivity in interaction with the analyte are of interest. Various derivatives of cellulose are used to obtain selective sorbents: ethylcellulose, hydroxypropylmethylcellulose (hypromellose), carboxymethylcellulose, etc. On the pharmaceutical market of the Russian Federation, there are pharmaceutical formulations with the active pharmaceutical substance salicylic acid. The use of selective SPE for analysis is a promising direction of research in drug quality control. Aim. Evaluation of the metrological characteristics of benzocaine quantitation by UV-spectrophotometry in certain pharmaceutical formulations using hypromellose sorbent for solid-phase extraction. Material and methods. The sorbent using a method developed by us was obtained. Salicylic acid (FS.2.1.0634, Russia State Pharmacopoeia XV ed.) to form active binding sites in sorbent structure was applied. The sorbent structure is polycyanoacrylate matrix with hypromellose fragments, the surface area is 255.50 m2/g, pore volume is 0.1433 cm3, pore diameter is 5.32 nm. The sorption capacity of hypromellose sorbent for benzocaine was 12.2 ± 0.8 μg/g. The SPE technique is proposed. SPE includes the stages: conditioning, sample addition and step-by-step elution with purified water and sodium hydroxide solution 0.1 mol/L. The spectrophotometer SF-56 was used to measure the absorbance at an analytical wavelength of 286 nm. To evaluate the selectivity (specificity) of sample preparation during chromatographic (SPE) separation of pharmaceutical formulations, absorption spectra of eluates in the wavelength range of 200-400 nm were scanned. The salicylic acid identification in the eluate was carried out based on absorption peaks at 228 and 298 nm.The salicylic acid calibration curve in the range of 1-20 μg/ml. To determination the metrological characteristics of salicylic acid quantitation method, 16 parallel determinations of samples of each pharmaceutical formulation were made. Statistical processing of the experimental results and determination of the metrological characteristics evaluation of analytical technique were carried out in accordance with general pharmacopoeial monograph (OFS.1.1.0013 "Statistical processing of results of physical, physicochemical, and chemical tests"). Results. When realizing the salicylic acid quantitation technique for measuring absorbance, it is advisable to use only the first portions of eluate (a solution of sodium hydroxide) in a volume of 5-10 ml were obtained. The relative error in determining the average content of salicylic acid in the analyzed preparations ranged from 1.18 to 1.44% for methods with solid-phase extraction (SPE) and 1.86-2.62% in its absence. It has been shown that there is a statistically significant difference in reproducibility for all preparations, as indicated by F-criteria values ranging from 7.81 to 13.5, exceeding their tabulated values. For the method without solid-phase extraction (SPE), there was an overestimation of the salicylic acid content in all cases, increasing the systematic error on average by 87.5%. Conclusion. The possibility of using a selective hypromellose sorbent for sample preparation for salicylic acid quantitation determination in pharmaceutical formulations has been showed. The use of sorbent for analysis provides to systematic error decrement of salicylic acid quantitation by an average of 87.5%.

Silica Grafted Imprinted Mesoporous Polymer for the Development of SPE Coupled FAAS Method of Nickel Determination, Removal, and Spent Polymer for Reduction of Permanganate: Multivariate Optimization

AbstractA novel silica fabricated allyloxy ethanol based imprinted polymer is synthesised with surface area of 333 m2 g−1 and average pore size of 6.5 nm by an environment friendly one pot surface imprinting process. It was employed for the selective solid‐phase extraction (SPE) of trace Ni(II) in real samples prior to FAAS determination. The factor settings produced via central composite design in response surface methodology (RSM) (pH: 3.6; initial concentration; 800 mg L−1 and time; 15 minute) provide adsorption capacity of 176 mg g−1. Artificial neural network model employed on the RSM data, provided better predictability. Sips isotherm model and BSf kinetic model describes best the sorption phenomena of the homogenous binding terrain. The developed SPE‐coupled FAAS method demonstrate a detection limit of 1.62 μg L−1, quantification limit of 4.17 μg L−1, and Linear dynamic range of 20–8000 μg L−1. It was successfully applied to determine nickel in food (Spinach, Radish, Green tea infusion, Black tea infusion, Coffee, Soya milk, Chocolate Soya milk, Tobacco) and wastewater samples (>99 % removal). For five replicate determinations, the method‘s relative standard deviation was 2.3 %. The method was validated by analysing two certified reference materials, and the outcomes were well‐congruent with standard values. For the synthesised polymer Ni(II) exhibits higher distribution ratio than other competing ions (Cu(II), Pb(II), Cd(II), and Zn(II)) with the imprinting factor; β values of 5.73, 4.98, 6.80, and 5.04 respectively. The reusability experiments revealed that APS@Ni‐IIP retains a strong adsorption efficacy even after 15 cycles and after its exhaustion it was employed as catalyst for reducing permanganate ions, further reducing pollution. The rigid structure of mesoporous silica contributes to its acid resilience and reusability, which can lead to a relative increase in polymer performance in absorption rate and selectivity. Apart from the novelty in the synthesis, thorough examination of the method and material selectivity (in binary, ternary and multielement system), multi fold applications of determination, removal of Ni(II) and reduction of permanganate ions, makes APS@Ni‐IIP a promising candidate for environmental remediation.

Mycotoxins-Imprinted Polymers: A State-of-the-Art Review.

Mycotoxins are toxic metabolites of molds which can contaminate food and beverages. Because of their acute and chronic toxicity, they can have harmful effects when ingested or inhaled, posing severe risks to human health. Contemporary analytical methods have the sensitivity required for contamination detection and quantification, but the direct application of these methods on real samples is not straightforward because of matrix complexity, and clean-up and preconcentration steps are needed, more and more requiring the application of highly selective solid-phase extraction materials. Molecularly imprinted polymers (MIPs) are artificial receptors mimicking the natural antibodies that are increasingly being used as a solid phase in extraction methods where selectivity towards target analytes is mandatory. In this review, the state-of-the-art about molecularly imprinted polymers as solid-phase extraction materials in mycotoxin contamination analysis will be discussed, with particular attention paid to the use of mimic molecules in the synthesis of mycotoxin-imprinted materials, to the application of these materials to food real samples, and to the development of advanced extraction methods involving molecular imprinting technology.

Selective and precise solid phase extraction based on a magnetic cellulose gold nanocomposite followed by ICP-OES analysis for monitoring of total sulfur content in liquid fuels.

This study describes the synthesis and characterization of a magnetic cellulose gold nanocomposite (MCNC@Au) for magnetic solid phase (m-SPE) extraction of total sulfur content in liquid fuel samples followed by analysis using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The nanocomposite was prepared using an in situ co-precipitation method and characterization results from FTIR, P-XRD, TEM and SEM-EDX techniques confirmed the formation of the targeted nanocomposite. To achieve good extraction efficiency, the 2-level half-fractional factorial design and central composite design were used to investigate the most influential parameters of the proposed m-SPE method. The multivariate optimization results showed that efficient extraction was obtained when 27.5 mg sorbent mass, 35 minutes sorption time, 200 μL eluent volume and 8 min elution time were used. The optimal parameters resulted in excellent accuracy (98.8%), precision (1.7%), LOD (0.039 mg L-1), LOQ (0.129 mg L-1), MDL (0.014 μg g-1) and MQL (0.047 μg g-1). The optimized and validated m-SPE method was applied in real fuel oil samples, revealing a total sulfur content range of 13.20 ± 0.05-15.70 ± 0.02 μg g-1 for crude oil, 7.32 ± 0.01-9.12 ± 0.03 for μg g-1, 8.41 ± 0.02-9.15 ± 0.06 μg g-1 for gasoline and 9.10 ± 0.02 and 9.70 ± 0.04 μg g-1 for kerosene samples, sugesting high concentration levels of sulfur in crude oils. However, the obtained sulfur content levels are within the accepted standards in fuel oils, except for those of crude oil and kerosene samples. Therefore, the proposed m-SPE method followed by ICP-OES analysis has proven to be an alternative procedure for rapid and selective quantification of total sulfur in fuel samples.

Molecularly imprinted polymers with ionic liquid as the functional monomer for selective solid-phase extraction of gastrodin

Gastrodia elata is a well-known Asian traditional herb with gastrodin (GAS; p-hydroxymethylbenzene-β-d-glucopyranoside) as its active ingredient. It is a challenging task to efficiently separate the active ingredient gastrodin from Gastrodia elata by simple procedure. The results of computer molecular simulation & UV-vis spectroscopy showed that water-soluble 1-vinyl-3-tetradecylimidazole bromide([C14VIM+] [Br-]) was selected as the best ionic liquid functional monomer compared with methacrylic acid(MAA), acrylic acid(AA), 3-(2-carboxyethyl)-1-vinylimidazolium bromide ionic liquid (imidazole propionate, [COOHpvimBr]), and dehydroabietic acid [2-(acryloyloxy)ethyl] ester (DAAEE). The force between [C14VIM+] [Br-] and GAS (with multiple hydroxyl groups) is stronger than other monomers with more polar groups. The molecular imprinted polymers (MIPs) and non- molecular imprinted polymers (NIPs) with high selectivity to gastrodin were synthesized utilizing ([C14VIM+] [Br-]) as a novel functional monomer. The polymer was characterized by infrared spectrum, scanning electron microscope, specific surface area tester and thermosgravimetric analyser(TGA). The adsorption performance of the polymer was investigated by adsorption kinetics experiment and static adsorption experiment. Among different eluents, the content of gastrodin in eluent (70% ethanol) significantly increased compared with it in plant extract by the MIPs-solid phase extraction (SPE)-HPLC. The recoveries of the spiked samples for the GAS were 97.75–103.43%, with relative standard deviation values lower than 2.88%. This novel [C14VIM+] [Br-]-based MIP was a potential separation material for gastrodin. The graphical abstract was shown below.

Molecularly imprinted polymers by reflux precipitation polymerization for selective solid-phase extraction of quinolone antibiotics from urine

Molecularly imprinted polymers (MIPs) possess high specific cavities towards the template molecules, thus solid-phase extraction (SPE) based on MIPs using the target as the template has been widely used for selective extraction. However, the performance of SPE depends strongly on the shape and the distribution of the MIP sorbents, and rapid synthesis of MIPs with uniform particles remains a challenge. Our previous studies have shown that reflux precipitation polymerization (RPP) was a simple and rapid method for the synthesis of uniform MIPs. However, synthesis of MIPs by RPP for a group of targets using only one of the targets as the template has rarely been reported. In this work, MIPs with specific recognition capability for a group of quinolone antibiotics were synthesized for the first time via RPP with only ofloxacin as the template. The synthesized MIPs displayed good adsorption performance and selectivity (IF > 3.5) towards five quinolones, and subsequently were used as SPE adsorbents. Based on this MIPs-SPE, after systematic optimization of the SPE operation parameters during loading, washing and elution, an efficient and sensitive enough SPE method for separation and enrichment of the five quinolones in urine was developed and evaluated in combination with LC-MS/MS. The results showed that MIPs-SPE-LC-MS/MS has a good correlation (R2 ≥ 0.9961) in the linear range of 1–500 μg L−1. The limit of detection (LOD) and limit of quantification (LOQ) for the five quinolones were 0.10–0.14 μg L−1 and 0.32–0.48 μg L−1, respectively. In addition, the proposed method demonstrated good reproducibility (≤ 13 %) and high accuracy (92 %–113 %). We are confident that this method holds significant promise for the analysis of quinolones within the contexts of forensic medicine, epidemiology, and environmental chemistry.

Dummy molecularly imprinted polymer-based solid-phase extraction method for the determination of some phthalate monoesters in urine by gas chromatography–mass spectrometry analysis

A dummy molecularly imprinted polymer-based solid-phase extraction (SPE) sorbent was used for the selective extraction of some phthalate monoesters, monoethyl phthalate (MEP), monobutyl phthalate (MnBP) and mono-(2-ethylhexyl) phthalate (MEHP) in urine prior to gas-chromatography-mass spectrometry (GC-MS) analysis. Diethyl phthalate (DEP), a phthalate ester, was successfully used as a dummy template to prepare selective sorbent for MEP, MnBP, and MEHP extraction. DEP-imprinted poly(ethylene glycol dimethacrylate N-methacryloyl-l-tryptophan methyl ester) (DPEMT) microbeads were synthesized by suspension polymerization and characterized by Fourier Transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and Brunauer Emmet Teller (BET) analysis. The critical parameters (i.e., pH, sorbent amount, ionic strength, sample volume, elution solvent) affecting the extraction performance of the DPEMT-SPE sorbent were optimized. Under optimum conditions, good linearities were obtained in the concentration range of 4 to 60 ng/mL with determination coefficients (R2) of greater than 0.9959. The developed SPE method provided low limits of detection (LOD) of 0.05–1.20 ng/mL and limits of quantification (LOQ) of 0.18–4.01 ng/mL with relative standard deviations (RSDs) of less than 8.95 % for intra- and inter-day analyses. The proposed SPE method was used to analyze phthalate monoesters in spiked urine samples, and recoveries of 97.45–109.26 % were obtained. DPEMT-SPE sorbent was reused for 15 times without any losses of performance. Consequently, a highly selective and sensitive SPE method based on a dummy molecularly imprinted polymer combined with GC-MS was successfully developed to monitor human phthalate exposure via urine samples.

Assessment of Molecularly Imprinted Polymers as Selective Solid-Phase Extraction Sorbents for the Detection of Cloxacillin in Drinking and River Water.

This paper describes a new methodology for carrying out quantitative extraction of cloxacillin from drinking and river water samples using a molecularly imprinted polymer (MIP) as a selective sorbent for solid-phase extraction (MISPE). Several polymers were synthesized via thermal polymerization using cloxacillin as a template, methacrylic acid (MAA) as a functional monomer, ethyleneglycoldimethacrylate (EGDMA) as a cross-linker and different solvents as porogens. Binding characteristics of the adequate molecularly imprinted and non-imprinted (NIP) polymers were evaluated via batch adsorption assays following the Langmuir and Freundlich isotherms and Scatchard assays. The parameters related to the extraction approach were studied to select the most appropriate polymer for cloxacillin determination. Using the optimized MIP as the SPE sorbent, a simple sample treatment methodology was combined with high-performance liquid chromatography (HPLC) to analyze cloxacillin residues in drinking and river water. Under the optimum experimental conditions, the MISPE methodology was validated using spiked samples. The linearity for cloxacillin was assessed within the limits of 0.05-1.5 µg L-1 and the recovery percentage was higher than 98% (RSD < 4%). The limits of detection and limits of quantification were 0.29 and 0.37 µg L-1 and 0.8 and 0.98 µg L-1 for drinking and river water, respectively. The selectivity of MIP against other ß-lactam antibiotics with similar structures (oxacillin, cefazoline, amoxicillin and penicillin V) was studied, obtaining a good recovery higher than 85% for all except cefazoline. The proposed MISPE-HPLC methodology was successfully applied for the detection of cloxacillin in drinking water from Canal de Isabel II (Madrid) and river water from the Manzanares River (Madrid).

Miniaturized point discharge optical emission spectrometry coupling with solid phase extraction: A robust approach for sensitive quantification of total mercury in mung bean sprout growth.

In this work, a portable chemical vapor generation point discharge optical emission spectrometry (CVG-PD-OES) system was designed for trace Hg2+ monitoring in mung bean sprout samples. The system incorporated selective solid phase extraction (SPE) to enhance the detection sensitivity. Gold nanoparticles (AuNPs) were prepared and utilized to extract trace amounts of Hg2+ by forming gold amalgam. Subsequently, the amalgam was desorbed using 5% HCl and introduced into a low-power PD-OES system analysis via CVG. A low limit of detection (LOD) of 0.16ngmL-1 was obtained with a linear range of 0.5-6ngmL-1. The well-designed system was successfully utilized for monitoring trace Hg2+ in the growth of mung beans. The results indicated that the Hg2+ in mung bean sprouts was continuously decreased during growth based on the metabolism. Furthermore, the risk assessment conducted implied a negligible hazard quotient, suggesting that the observed levels of exposure posed minimal risk.

Synthesis and characterization of pH-sensitive thin-layer molecularly imprinted membranes for selective solid-phase extraction of celecoxib from biological fluids followed by high-performance liquid chromatography with UV detection

In this work, the synthesis of thin-layer, pH-sensitive molecularly imprinted membrane using methacrylic acid and maleic acid as functional monomers, ethylene glycol dimethacrylate as cross-linker, 2,2′-azobisisobutyronitrile as initiator, poly (vinylidene fluoride) as porous membrane, and celecoxib as a target molecule have been reported. Different technique analyses characterized the membrane product. A novel molecularly imprinted membrane-solid phase extraction method was used for the extraction of celecoxib and concentrating it prior to be analyzed in the human plasma and urine matrix. High-performance liquid chromatography with ultraviolet detection was used and validated for the analysis of celecoxib which was extracted from biological fluids. The molecularly imprinted membrane showed selective performance for the template, and extraction recoveries of the drug by the membrane from human plasma and urine samples were between 96.2 and 97.3%. The obtained results showed that the detection and quantification limits of the drug were 0.12 and 0.40 ng mL−1, respectively. The adsorption capacity of 4.95 mg g−1 was obtained from the fitting by the Langmuir model. The molecularly imprinted membrane can be easily regenerated eight times with sustained efficiency. Therefore, the developed method can be a good candidate for the separation and detection of celecoxib in biological samples.

A molecularly imprinted polymer monolithic column with dual template and bifunctional monomers for selective extraction and simultaneous determination of eight phenolics from polycarbonate cups

A molecularly imprinted polymer (MIP) monolithic column was prepared in situ in a pipette tip using phenol and bisphenol A as dual templates, 4-vinyl pyridine and β-cyclodextrin as bifunctional monomers. It was used for the selective and simultaneous solid phase extraction of eight phenolics, including phenol, m-cresol, p-tert-butylphenol, bisphenol A, bisphenol B, bisphenol E, bisphenol Z, and bisphenol AP. The MIP monolithic column was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and nitrogen adsorption experiment. The results of selective adsorption experiments showed that the MIP monolithic column can selective recognize the phenolics and have excellent adsorption property. The imprinting factor for bisphenol A can be as high as 4.31, and the maximum adsorption capacity for bisphenol Z can reach 201.66 mg g−1. Under the optimal extraction conditions, a selective and simultaneous extraction and determination method for eight phenolics was established based on the MIP monolithic column and high-performance liquid chromatography with ultraviolet detection. The linear ranges (LRs) of the eight phenolics were 0.5–200 μg L−1, the limits of quantification (LOQs) and detection (LODs) were 0.5–2.0 μg L−1 and 0.15–0.67 μg L−1. The method was applied to detect the migration quantity of the eight phenolics from polycarbonate cups and had satisfactory recovery. The method has the advantages of simple synthesis, short extraction time, as well as good repeatability and reproducibility, which provides a sensitive and reliable strategy for extracting and detecting phenolics from food contact material.

Experimental strategy for acid-free plutonium recovery from assorted matrices: Non-aqueous leaching followed by selective solid phase extraction

Experimental strategy for acid-free plutonium recovery from assorted matrices: Non-aqueous leaching followed by selective solid phase extraction

Synthesis and Characterization of a New Molecularly Imprinted Polymer for Selective Extraction of Mandelic Acid Metabolite from Human Urine as a Biomarker of Environmental and Occupational Exposures to Styrene.

4-Vinylpyridine molecularly imprinted polymer (4-VPMIP) microparticles for mandelic acid (MA) metabolite as a major biomarker of exposure to styrene (S) were synthesized by bulk polymerization with a noncovalent approach. A common mole ratio of 1:4:20 (i.e., metabolite template: functional monomer: cross-linking agent, respectively) was applied to allow the selective solid-phase extraction of MA in a urine sample followed by high-performance liquid chromatography-diode array detection (HPLC-DAD). In this research, the 4-VPMIP components were carefully selected: MA was used as a template (T), 4-Vinylpyridine (4-VP) as a functional monomer (FM), ethylene glycol dimethacrylate (EGDMA) as a cross-linker (XL), and azobisisobutyronitrile (AIBN) as an initiator (I) and acetonitrile (ACN) as a porogenic solvent. Non-imprinted polymer (NIP) which serves as a "control" was also synthesized simultaneously under the same condition without the addition of MA molecules. Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) were used to characterize the imprinted and nonimprinted polymer to explain the structural and morphological characteristics of the 4-VPMIP and surface NIP. The results obtained from SEM depicted that the polymers were irregularly shaped microparticles. Moreover, MIPs surfaces had cavities and were rougher than NIP. In addition, all particle sizes were less than 40 µm in diameter. The IR spectra of 4-VPMIPs before washing MA were a little different from NIP, while 4-VPMIP after elution had a spectrum that was almost identical to the NIP spectrum. The adsorption kinetics, isotherms, competitive adsorption, and reusability of 4-VPMIP were investigated. 4-VPMIP showed good recognition selectivity as well as enrichment and separation abilities for MA in the extract of human urine with satisfactory recoveries. The results obtained in this research imply that 4-VPMIP might be used as a sorbent for MA solid-phase extraction (MISPE), for the exclusive extraction of MA in human urine.