Selective Sorbent For Solid-phase Extraction Research Articles

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).

Preparation and evaluation of molecularly imprinted polymers as selective SPE sorbents for the determination of cathinones in river water

In this study, a series of molecularly imprinted polymers (MIPs) were synthesised using (1R,2S)-(–)-ephedrine or (1S,2S)-(+)-pseudoephedrine as template, methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linking agent. A highly selective and sensitive method using the best performing MIP as sorbent in the solid-phase extraction (SPE) followed by liquid chromatography-high resolution mass spectrometry was established for the enantiomeric determination of five cathinones in river water samples. The SPE parameters (sample loading volume and pH, washing and elution solutions) were optimised so that recoveries and selectivities for the analytes were high. The enantioselectivity of MIPs towards the enantiomers of the analytes during the SPE process was also investigated. Under optimal conditions, the method developed provided satisfactory recoveries ranging from 67.6 to 83.2 % with a negligible matrix effect ranging from −5.5 to 1.8 %. The detection limits ranged from 0.3 to 0.8 ng/L and quantification limits ranged from 1.0 to 2.0 ng/L. The application of the method to the analysis of the river water samples indicated that methedrone and butylone were present at low concentration levels in river water samples.

Development of Molecularly Imprinted Membranes for Selective Determination of Urinary Ultra-Trace 5-Fluorouracil as Antineoplastic Drug Used in Chemotherapy

The incidence of neoplasm has significantly increased around the world over the last decades, resulting in use of anti-neoplastic drugs and the potential for occupational exposure to these drugs. One of the most commonly used chemotherapeutic drugs for treatment of malignancies is 5-fluorouracil (5-FU). In this study, in order to develop an appropriate adsorbent for selective extraction of ultra-trace 5-fluorouracil from urine samples, molecularly imprinted membranes (MIMs) of 5-FU were prepared by encapsulating molecularly imprinted polymer nanoparticles (MIP-NPs) into the electrospun polyethylene terephthalate (PET) nanofibers. The MIP-NPs encapsulated into electrospun PET nano-fibers were prepared by precipitation polymerization technique. These MIMs were used as selective sorbents for solid-phase extraction (SPE) of ultra-trace 5-FU from different samples prior to the analysis by high performance liquid chromatography (HPLC). Central Composite Design (CCD) was used for optimization of effective parameters in sorption and desorption steps of the molecularly imprinted membrane solid phase extraction (MIMSPE). The optimum operating conditions for the proposed method were pH: 6.2, amount of sorbent: 10.3 mg and absorption time: 20.5 h, the volume of eluent: 1 mL, the composition of elution solvent: the ratio of 90.3:9.7 methanol and acetic acid, and desorption time: 1.27 h. Under these optimized conditions, the limit of detection for 5-FU by MIMSPE was 0.07 μ L-1. The recoveries of 5-FU from urine sample ranged from 92.95±3.85 to 94.85±2.85%. The proposed MIMSPE-HPLC method can potentially be applied for selective detection of 5-FU in real samples with no special sample pretreatment steps.

Novel MIPs-Parabens based SPE Stationary Phases Characterization and Application.

In this work, the synthesis, characterization, and application of novel parabens imprinted polymers as highly selective solid-phase extraction (SPE) sorbents have been reported. The imprinted polymers were created using sol–gel molecular imprinting process. All the seven parabens were considered herein in order to check the phase selectivity. By means of a validated HPLC-photodiode array detector (PDA) method all seven parabens were resolved in a single chromatographic run of 25 min. These SPE sorbents, in-house packed in SPE empty cartridges, were first characterized in terms of extraction capability, breakthrough volume, retention volume, hold-up volume, number of theoretical plates, and retention factor. Finally, the device was applied to a real urine sample to check the method feasibility on a very complex matrix. The new paraben imprinted SPE sorbents, not yet present in the literature, potentially encourage the development of novel molecularly imprinted polymers (MIPs) to enhance the extraction efficiency, and consequently the overall analytical performances, when the trace quantification is required.

Application of selective solid-phase extraction using a new core-shell-shell magnetic ion-imprinted polymer for the analysis of ultra-trace mercury in serum of gallstone patients

ABSTRACT A new ultrasonically assisted spectrophotometric method was developed using stabilized ion polymer on a modified nano-absorbent as a core- shell-shell absorbent (Fe3O4@SiO2@TiO2–IIP). It has the advantages of further stabilizing the polymer and consequently and much higher efficiency than its conventional adsorbents. The prepared sorbent was characterized and Its parameters were investigated by a Box–Behnken design. The linear dynamic range and limit of detection were 0.20–28.00 µg L−1 and 0.05 µg L−1 respectively. In selectivity study, it was founded that imprinting causes increased affinity of the prepared IIP toward Hg2+ ion. The proposed IIP is considered to be promising and selective sorbent for solid-phase extraction and preconcentration of Hg2+ ion in sera of different types of gallstone patients.

Synthesis, characterization, and application of griseofulvin surface molecularly imprinted polymers as the selective solid phase extraction sorbent in rat plasma samples

In present study, an investigation was carried out to develop and validate an analytical method for the selective extraction and determination of griseofulvin (GSF) from plasma samples. For this purpose, a rational approach was made to synthesize and characterize the surface molecularly imprinted polymers (SMIPs). The SMIPs were utilized as solid phase extraction (SPE) sorbents. The SMIPs were prepared by using GSF as template molecule on the surface of modified silica particles through a non-covalent technique. The particles demonstrated high adsorption capacity (119.1 µg/mL), fast adsorption equilibrium time (30 min) and good recognition selectivity for the template drug. The scanning electron microscopy and infrared spectroscopy were used to explain the structural and morphological characteristics of the SMIPs and surface non-imprinted polymers. The SPE method was combined with HPLC for plasma analysis. The method validation results demonstrated that the established method possessed good linearity for GSF ranging from 0.1 to 50 µg/mL (R2 = 0.997). The limit of detection for this method was 0.02 µg/mL for rat plasma samples. The recoveries of GSF from spiked plasma samples were (90.7–97.7%) and relative standard deviations were (0.9–4.5%). Moreover, the SMIPs as selective SPE sorbent can be reused more than 8 times which is a clear advantage over commercial SPE sorbents. Finally, the usefulness of the proposed strategy was assessed by extraction and detection of GSF in real rat plasma samples.

Preparation of molecularly imprinted polymers coupled with high-performance liquid chromatography for the selective extraction of salidroside from Rhodiola crenulata

Salidroside is one of the bio-active compounds found in Rhodiola crenulata. To find an easy, time saving and efficient way to extract, purify and enrich salidroside from Rhodiola and other natural plants, we prepared a highly selective molecularly imprinted polymer (MIP) for extraction and preconcentration of salidroside using salidroside (SD) as a template, acrylamide (AM) as a functional monomer, ethylene glycol dimethacrylate (EDMA) as a crosslinking monomer, and dimethyl formamide (DMF) as a porogen. The performance of the MIPs was evaluated through selective recognition capacity and adsorption isotherms and kinetics. The results showed that MIPs possessed excellent specific recognition toward SD and could effectively discriminate its structural analogue. The application of the developed MIPs as a selective sorbent for solid-phase extraction (SPE) of SD was also investigated. Under the optimum conditions, a rapid, economical, and efficient method based upon MIP-SPE coupled with high-performance liquid chromatography (HPLC) was developed for the determination of SD in Rhodiola crenulata. The method showed satisfactory recoveries (from spiked real samples at 3 fortification levels of 0.5, 1 and 10 mg L−1) of 88.74%- 97.64% with relative standard deviations (RSDs) ranging from 2.05%–3.54%. Furthermore, MIP-SPE was successfully used to separate and purify SD from different parts in Rhodiola crenulata and it should be available for determination of salidroside in others herbs.

Synthesis quercetin imprinted polymer by precipitation polymerization method, directed to apply as sorbent for selective solid-phase extraction

Synthesis quercetin imprinted polymer by precipitation polymerization method, directed to apply as sorbent for selective solid-phase extraction

A Phenolphthalein-Dummy Template Molecularly Imprinted Polymer for Highly Selective Extraction and Clean-Up of Bisphenol A in Complex Biological, Environmental and Food Samples.

A molecularly imprinted polymer (MIP) for highly selective solid-phase extraction (SPE) of bisphenol A (BPA) was prepared using phenolphthalein (PP) as the novel dummy template by bulk polymerization. A particle diameter distribution of 40–60 μm, a specific surface area of 359.8 m2·g−1, and a total pore volume of 0.730 cm3·g−1 for the prepared PP-imprinted polymer (PPMIP) were obtained. Good selectivity and specific adsorption capacity for BPA of the prepared PPMIP were also demonstrated by the chromatographic evaluation and sorption experiments. The PPMIP as a SPE sorbent was evaluated for the selective extraction and clean-up of BPA from complex biological, environmental, and food samples. Meanwhile, an accurate and sensitive analytical method based on the PPMIP-SPE purification procedure coupled with high performance liquid chromatography-diode array detector (HPLC-DAD) detection has been successfully developed for the rapid determination of BPA from these samples, with detection limits of 1.3 ng·mL−1 for bovine serum and milk, 2.6 ng·mL−1 for human urine and edible oil, 5.2 ng·mL−1 for soybean sauce, and 1.3 ng·g−1 for sediment. The BPA recoveries at two different spiking levels were in the range of 82.1–106.9%, with relative standard deviation (RSD) values below 7.7%.

Molecular imprinting on surface of silica particles for the selective extraction of benzylparaben in flow system applied to cosmetics and water samples

Molecular imprinted polymer coated Silica (Si-MIP) particles were prepared using non-covalent approach. The Si-MIP material was employed as selective solid phase extraction sorbent for the determination of benzylparaben (BP) in samples of environmental and cosmetic origin. The preconcentration step was studied firstly in a batch system and subsequently it was optimized and adapted to an automatized flow system and the eluate was then analyzed by HPLC-UV. The whole procedure was validated, showing satisfactory analytical parameters. The methodology was applied to real samples showing extraction recoveries always better than 98.85%. A linear response within the concentration range of 1.11 × 10−5–0.025 mg mL−1 was obtained for BP (r2 = 0.9998). The limits of detection and quantification after Si-MIP-HPLC procedure were 3.34 and 11.16 ng mL−1, respectively. The developed methodology provided a simple an economic way for accomplishing a clean-up/preconcentration step and the subsequent determination of BP in a complex matrix. The showed selectivity plus robustness and the possibility of reutilization, enable it to be used for BP routine monitoring in personal care products (PCP) and environmental samples.

Selective solid-phase extraction using a molecularly imprinted polymer for the analysis of patulin in apple-based foods.

The aim of this work was to evaluate the use of a molecularly imprinted polymer as a selective solid-phase extraction sorbent for the clean-up and pre-concentration of patulin from apple-based food products. Ultra high pressure liquid chromatography coupled to ultraviolet absorbance detection was used for the analysis of patulin. The molecularly imprinted polymer was applied, for the first time, to the determination of patulin in apple juice, puree and jam samples spiked within the maximum levels specified by the European Commission No. 1881/2006. High recoveries (>77%) were obtained. The method was validated and found to be linear in the range 2-100 μg/kg with correlation coefficients greater than 0.965 and repeatability relative standard deviation below 11% in all cases. Compared with dispersive solid-phase extraction (QuEChERS method) and octadecyl sorbent, the molecularly imprinted polymer showed higher recoveries and selectivity for patulin. The application of Affinisep molecularly imprinted polymer as a selective sorbent material for detection of patulin fulfilled the method performance criteria required by the Commission Regulation No. 401/2006, demonstrating the suitability of the technique for the control of patulin at low ppb levels in different apple-based foods such as juice, puree and jam samples.

Highly selective solid-phase extraction sorbents for chloramphenicol determination in food and urine by ion mobility spectrometry

Different highly selective sorbents have been evaluated for the treatment of food and biological samples to determine chloramphenicol residues by ion mobility spectrometry (IMS). Combination of a selective solid-phase extraction (SPE) and dispersive liquid-liquid microextraction allowed a highly sensitive determination of chloramphenicol in water, milk, honey, and urine samples. The performance of selective SPE supports such as immunoaffinity chromatography (IAC) and molecular imprinted polymers (MIP) have been compared in terms of selectivity, sensitivity, trueness, precision, and reusability. Quantitative recoveries were obtained for chloramphenicol residues, ranging from 91 to 123% for water, from 99 to 120% for skimmed milk, and from 95 to 124% for urine using IAC-IMS and MIP-IMS methods. Quantitative recoveries (from 88 to 104%) were also achieved for honey samples using IAC-IMS, but low recoveries were obtained using MIP-IMS. The limit of quantification was set at 0.1μgL-1 which is lower than the minimum required performance limit established by the EU. The proposed methodology is a simple and cost affordable alternative to chromatography methods for the highly sensitive and selective analysis of chloramphenicol residues in food and urine. Graphical Abstract Scheme for chloramphenicol determination by selective solid-phase extraction and ion mobility spectrometry.

Preparation of l-phenylalanine-imprinted solid-phase extraction sorbent by Pickering emulsion polymerization and the selective enrichment of l-phenylalanine from human urine.

A novel l-phenylalanine molecularly imprinted solid-phase extraction sorbent was synthesized by the combination of Pickering emulsion polymerization and ion-pair dummy template imprinting. Compared to other polymerization methods, the molecularly imprinted polymers thus prepared exhibit a high specific surface, large pore diameter, and appropriate particle size. The key parameters for solid-phase extraction were optimized, and the result indicated that the molecularly imprinted polymer thus prepared exhibits a good recovery of 98.9% for l-phenylalanine. Under the optimized conditions of the procedure, an analytical method for l-phenylalanine was well established. By comparing the performance of the molecularly imprinted polymer and a commercial reverse-phase silica gel, the obtained molecularly imprinted polymer as an solid-phase extraction sorbent is more suitable, exhibiting high precision (relative standard deviation 3.2%, n = 4) and a low limit of detection (60.0 ± 1.9 nmol·L(-1) ) for the isolation of l-phenylalanine. Based on these results, the combination of the Pickering emulsion polymerization and ion-pair dummy template imprinting is effective for preparing selective solid-phase extraction sorbents for the separation of amino acids and organic acids from complex biological samples.

Facile synthesis of cysteine functionalized magnetic graphene oxide nanosheets: Application in solid phase extraction of cadmium from environmental sample

A facile method for synthesis of cysteine functionalized magnetic graphene oxide nanosheets is introduced. In comparison with other metal ions, cysteine has more affinity to coordinate with cadmium, therefore, the modified graphene oxide nanosheets were used as a selective sorbent for solid-phase extraction and determination of trace cadmium in different food samples (rice, wheat, milk and shrimp). Satisfactory recoveries were obtained by using 0.8mgmL−1 of sorbent in a pH range of 5–9. The results showed good adsorption capacities (24.39–30.30mgg−1 at 298–328K) of the adsorbent with the high selectivity toward cadmium ions. The process was relatively fast and the equilibrium was established within 5min and its kinetics followed the pseudo-second order mechanism. The best interpretation for the equilibrium data was given by Langmuir isotherm and the thermodynamic parameters showed that the adsorption process was spontaneous, endothermic and chemical in nature.

A new sorbent based on MWCNTs modification for separation/preconcentration of trace amounts of Cd(II), Cr(III), Cu(II), Ni(II), and Pb(II) and their determination by flame atomic absorption spectrometry

A new solid phase extraction (SPE) method has been developed for the separation/preconcentration and determination of lead, cadmium, chromium, nickel, and copper ions using a new sorbent. The method is based on the application of multiwalled carbon nanotubes modified with ethylenediamine-N,N-diacetic acid (MWCNTs-EDDA) as a selective sorbent in SPE for the separation and preconcentration of Pb(II), Ni(II), Cd(II), Cu(II), and Cr(III). The determination of these heavy metals was followed by flame atomic absorption spectrometry (FAAS). All quantitative determinations were performed by FAAS, and surface modification of synthesized adsorbents has been confirmed on the basis of characterization with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The parameters such as pH, amount of adsorbent, shaking time, eluent type and its concentration, and matrix effect have been investigated and optimized. The maximum adsorption capacity of the adsorbent at optimum conditions was found to be 51.7, 67.6, 49.9, 57.8, and 62.3 mg g-1 for Cd(II), Cr(III), Cu(II), Ni(II), and Pb(II), respectively. In the presented study, MWCNTs were functionalized by EDDA and it was applied as an adsorbent for the separation and preconcentration of trace level of Pb, Ni, Cd, Cu, and Cr ions. This method is effective, selective, rapid, and simple for the determination of trace amounts of Pb, Ni, Cd, Cu, and Cr ions and can be successfully applied to analyze the trace amounts of mentioned ions in wastewater and herbal samples without evident interference from the complex matrix. Furthermore, the sorption has high capacity, and the precision and accuracy of the method are also satisfactory.

Synthesis, characterization and application of ion imprinted polymeric nanobeads for highly selective preconcentration and spectrophotometric determination of Ni2 + ion in water samples

Here, the researchers report on the synthesis of ion imprinted polymeric (IIP) nanoparticles using a thermal polymerization strategy, and their usage for the separation of Ni2+ ion from water samples. The prepared Ni-IIP was characterized by colorimetry, FT-IR spectroscopy, and scanning electron microscopy. It was found that the particle size of the prepared particle to be 50–70nm in diameter with the highly selective binding capability for Ni2+ ion, with reasonable adsorption and desorption process. After preconcentration, bound ions can be eluted with an aqueous solution of hydrochloric acid, after their complexation with dimethylglyoxime, these ions can be quantified by UV–Vis absorption spectrophotometry. The effect of various parameters on the extraction efficiency including pH of sample solution, adsorption and leaching times, initial sample volume, concentration and volume of eluent were investigated. In selectivity study, it was found that imprinting causes increased affinity of the prepared IIP toward Ni2+ ion over other ions such as Na+, K+, Ag+, Co2+, Cu2+, Cd2+, Hg2+, Pb2+, Zn2+, Mn2+, Mg2+, Cr3+, and Fe3+. The prepared IIP can be used and regenerated for at least eight times without any significant decrease in binding affinities. The prepared IIP is considered to be promising and selective sorbent for solid-phase extraction and preconcentration of Ni2+ ion from different water samples.

Synthesis of a molecularly imprinted sorbent for selective solid-phase extraction of β-N-methylamino-l-alanine

The aim of the work was to synthesize a molecularly imprinted material for the selective solid-phase extraction (SPE) of β-N-methylamino-l-alanine (l-2-amino-3-methylpropionic acid; BMAA) from cyanobacterial extracts. BMAA and its structural analogs that can be used as template are small, polar and hydrophilic molecules. These molecules are poorly soluble in organic solvents that are commonly used for the synthesis of acrylic-based polymers. Therefore, a sol gel approach was chosen to carry out the synthesis and the resulting sorbents were evaluated with different extraction procedures in order to determine their ability to selectively retain BMAA. The presence of imprinted cavities in the sorbent was demonstrated by comparing elution profiles obtained by using molecularly imprinted silica (MIS) and non-imprinted silica (NIS) as a control. The molecularly imprinted solid-phase extraction (MISPE) procedure was first developed in a pure medium (acetonitrile) and further optimized for the treatment of cyanobacterial samples. It was characterized by high elution recoveries (89% and 77% respectively in pure and in real media).The repeatability of the extraction procedure in pure medium, in real medium and the reproducibility of MIS synthesis all expressed as RSD values of extraction recovery of BMAA were equal to 3%, 12% and 5%, respectively. A MIS capacity of 0.34µmol/g was measured. The matrix effects, which affected the quantification of BMAA when employing a mixed mode sorbent, were completely removed by adding a clean-up step of the mixed-mode sorbent extract on the MIS.

Molecularly Imprinted Polymer Preconcentration and Flow Injection Amperometric Determination of 4-Nitrophenol in Water

Molecularly imprinted polymers are reported as selective solid-phase extraction sorbents for the preconcentration of 4-nitrophenol in water. A graphite pencil electrode modified with multiwalled carbon nanotubes provided good sensitivity and excellent anti-fouling properties for flow injection amperometry. Solid-phase extraction cartridges containing 100 mg of imprinted polymers with a sample volume of 50 mL resulted in a preconcentration factor of 97.7, which allowed determination of 4-nitrophenol at the maximum level permitted by the United States Environmental Protection Agency (60 µg L−1). A linear dynamic range of 5–300 µg L−1 for 4-nitrophenol was obtained with a limit of detection of 1.5 µg L−1. The method was employed for the determination of 4-nitrophenol in water.

Determination of Diazinon Pesticide Residue in Tomato Fruit and Tomato Paste by Molecularly Imprinted Solid-Phase Extraction Coupled with Liquid Chromatography Analysis

In the present study, an optimized molecularly imprinted polymer (MIP) was prepared and evaluated as a selective sorbent in solid-phase extraction and analysis in tomato fruit and tomato paste. The MIP was prepared using methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linking monomer, and chloroform as the solvent. Binding properties of MIP was studied in comparison with non-imprinted polymer. MIP was applied, as a sorbent, for extraction and preconcentration of diazinon from tomato fruit and tomato paste. The analytical method was calibrated, in the range of 0.01 to 2 mg kg−1. The results indicated that the optimized MIP had an excellent affinity for diazinon. The molecularly imprinted solid-phase extraction procedure was developed and optimized with a recovery of 82–116 % in tomato fruit and recovery of 80–110 % in tomato paste. The intra-day variation and inter-day variation values were less than 8.16 % and 9.8 %, respectively. Finally, diazinon content of tomato fruit and tomato paste, in Mashhad city in February 2014, was evaluated using calibrated analytical method. The amounts of diazinon residue in tomato fruit was varied between 0.20 and 0.64 mg kg−1, whereas the value in tomato paste was varied between 0.02 and 0.31 mg kg−1. According to our data, the amount of diazinon residue in tomato paste, in Mashhad city, was less than the maximum residue limit (MRL) of diazinon in tomato set by the World Health Organization (0.5 mg kg−1), whereas this value was higher than MRL in tomato fruit samples of Mashhad, Nishabur, and Chenaran cities.

Molecularly imprinted polymer-based, solid-phase extraction followed by liquid chromatographic determination of lacosamide in rat plasma

A novel sample clean-up technique, water-compatible, molecularly imprinted, solid-phase extraction (MISPE), combined with high-performance liquid chromatography (HPLC), was developed and validated for selective extraction and determination of lacosamide in rat plasma. The molecularly imprinted polymer (MIP) was synthesized using methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, chloroform as a porogen, and lacosamide as a template. Its efficacy as a selective sorbent in solid-phase extraction of lacosamide and the effects of various porogenic solvents, pH, crosslinker, and amount of monomer were studied and optimized. The recovery was >98% with a detection limit of 0.03 μg mL−1 over a linear range of 0.1–100 μg mL−1.