Molecularly Imprinted Solid-phase Extraction Research Articles

Quantitative Analysis of Artificial Sweeteners by Capillary Electrophoresis with a Dual‐Capillary Design of Molecularly Imprinted Solid‐Phase Extractor

A novel coupling system of capillary electrophoresis (CE) and monolithic molecularly imprinted polymer (MIP) was developed for selective and sensitive determination of sweeteners; sucrose, sucralose, and aspartame, based on an in‐column and open‐tube molecularly imprinted solid‐phase extraction (MISPE) concentrator. The MISPE was fabricated by coating a short layer of MIP material (about 3 mm long) directly at the inlet end of the inner wall of capillaries under the irradiation of light emitting diode (LED). Compared with the conventional methods using hydrodynamic injection by MISPE fiber, the MISPE concentrator provides increase in sensitivity without significant loss of separation efficiency. In this work, LED‐induced in‐multiple capillary MISPE was used for extraction and determination of artificial sweeteners, sucrose, sucralose, and aspartame, from beverage samples. The results of MISPE showed good extraction ability with the enrichment ratios of >150 for sucrose and sucralose, and of >200 for aspartame with acceptable analytical performance. The reproducibility of on‐line MISPE concentrator was 1.6% for sucralose and 2.7% for aspartame under the same fixed set of experimental conditions. The developed multiple MISPE system has been successfully adapted for practical application for commercial soda drink samples.

Modification of mesoporous silica with molecular imprinting technology: A facile strategy for achieving rapid and specific adsorption

In order to improve the diffusion kinetics of molecularly imprinted materials (MIMs), applying imprinting technology to mesoporous materials is a promising strategy. In the present study, an imprinting approach based on the combination of mesoporous silica materials and molecular imprinting technology is reported. Molecularly imprinted material (MIM) for 2,4-dichlorophenoxyacetic acid (2,4-D) was prepared by using 2,4-D as the template molecule, alkyne-modified β-cyclodextrin and propargyl amine as the combinatorial functional monomers and SBA-15 as the supporter. The functional monomers were anchored to the azide-modified SBA-15 by azide–alkyne Click reaction. The synthesized MIM was characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), thermal gravimetric analysis (TGA), low-angle X-ray diffraction (XRD) and N2 adsorption–desorption analysis. The interactions between template and functional monomers were studied by proton NMR analysis and UV–vis experiments. The results of the equilibrium binding experiments and selective tests showed that the prepared MIM has binding affinity and specificity for a group of analytes which have similar size and shape to those of template. Binding kinetic experiments demonstrated that the present imprinting approach can effectively enhance the mass transfer rate. The solid phase extraction of 2,4-D using MIM as the adsorbent was investigated. The extraction conditions for the processes of loading, washing and eluting were optimized. The recoveries of the molecularly imprinted solid phase extraction (MISPE) column for 2,4-D were 76.3–88.9% with relative standard deviations (RSD) of 3.48–7.64%.

Rapid determination of Alternaria mycotoxins in tomato samples by pressurised liquid extraction coupled to liquid chromatography with fluorescence detection

ABSTRACTA sensitive and reliable method using pressurised liquid extraction (PLE) followed by molecularly imprinted solid phase extraction (MISPE) and high performance liquid chromatography with fluorescence detection (HPLC–FLD) has been developed for the analysis of alternariol (AOH) and alternariol monomethyl ether (AME) in tomato samples. Influence of several extraction parameters that affect PLE efficiency were evaluated for the simultaneous extraction of both mycotoxins in the selected samples. AOH and AME were optimally extracted using MeOH/water (25:75, v/v) at 70°C as solvent, a pressure of 1000 psi and a single extraction cycle. The resulting PLE extracts were pre-concentrated by molecularly imprinted solid phase extraction (MISPE) cartridges followed of analysis by HPLC with fluorescence detection (λexc = 258, λem = 440 nm). The proposed method was applied to the analysis of AOH and AME in fortified tomato samples (20–72 µg· kg–1) with recoveries of 84–97% (RSD < 8%, n = 6) for AOH and 67–91% (RSD < 13%, n = 6) for AME. The detection limit for AOH and AME were 7 and 15 µg· kg–1, respectively. The ensuing PLE–MISPE–HPLC–FLD method was validated for the analysis of both mycotoxins in tomato samples in accordance with European Commission Decision 2002/657/EC.

Preparation and characterization of molecularly imprinted solid-phase extraction column coupled with high-performance liquid chromatography for selective determination of melamine.

We synthesized a selective molecularly imprinted solid-phase extraction (MIP-SPE) column and established an extraction and enrichment method using this MIP-SPE column. By coupling with HPLC, we developed a new method to detect trace amounts of melamine in eggs. The MIP-SPE column was synthesized by in situ thermal-initiated polymerization using melamine as the template, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker and azodiisobutyronitrile as the initiator. HPLC was used to evaluate the identification and enrichment capability of the MIP-SPE column and for the measurement of melamine in the sample. The melamine concentration exhibited an excellent linear relationship in the range of 0.1–25.0 µg ml−1 (r = 0.9983). The identification capability of the MIP-SPE column was apparently superior to that of the non-imprinted polymer solid-phase extraction column; an average enrichment factor of 46.8-fold (RSD = 3.5%) was obtained for 0.4 µg ml−1 melamine by the MIP-SPE column. When the MIP-SPE HPLC method was applied to the detection of melamine in eggs, an average recovery rate of 93.5–102.0% (RSD = 3.6–4.9%) and a limit of detection of 0.05 µg kg−1 were obtained. This method is simple, fast and cost-effective; thus, it can greatly simplify the pre-treatment of complex samples and can be used in the detection of residual melamine in eggs and other products.

Superhydrophilic molecularly imprinted polymers based on a single cross-linking monomer for the recognition of iridoid glycosides in Di-huang pills.

An efficient analytical method based on molecularly imprinted solid-phase extraction (MISPE) coupled with high-performance liquid chromatography-diode array detection (HPLC-DAD) was established for the determination of iridoid glycosides (IGs) in Di-huang pills. As the solid-phase extraction medium, superhydrophilic molecularly imprinted polymers (MIPs) with high affinity and selectivity to IGs in water media were fabricated using divinyl galactose as a single cross-linking monomer. The structure, porosity, and hydrophilicity of MIPs were characterized. The properties involving dynamic adsorption, kinetic adsorption, and selectivity were evaluated. Under optimal conditions the MISPE-HPLC-DAD basedmethod was applied for loganin, morroniside, cornin, and sweroside determination in three kinds of Di-huang pills. The limits of detection of four IGs were 0.002-0.003mgg-1. Furthermore, the proposed method exhibited some merits including good linearity, excellent precision, and desirable accuracy. The established MISPE-HPLC-DAD method has great potential for the selective determination of IGs in Chinese patent drugs. Graphical Abstract ᅟ.

Synthesis of molecular imprinted polymer nanoparticles followed by application of response surface methodology for optimization of metribuzin extraction from urine samples

A molecular imprinted polymer was prepared with precipitation polymerization technique and applied as a sorbent for selective extraction and enrichment of metribuzin herbicide prior to high performance liquid chromatography. Optimization of critical variables affecting the efficiency of molecularly imprinted solid-phase extraction (MISPE), such as sorbent mass, sample pH and flow rate of sample, volume, concentration, and flow rate of elution solvent was done by employing central composite design (CCD) of the response surface methodology. Two separate models were developed for the adsorption and recycling steps. The analysis of variance (ANOVA) demonstrated that, experimental data were excellently fitted to the proposed response models. The optimum operating conditions were: a sorbent mass of 25 mg, sample pH 6.19, sample flow rate of 2.15 mL/min, and a 5 mL portion of methanol/acetic acid with 92.7:7.3 (v/v) ratio and flow rate of 2.1 mL/min for the extraction process. Under the optimized conditions, the linear range was obtained from 20 to 120 µg/L (R2 = 0.999) and the lowest detectable concentration (LOD) and the lowest quantitative concentration (LOQ) were calculated as 5.75 and 19.86 µg/L, respectively. Finally, the designed MISPE method was successfully applied to determine trace amount of metribuzin in real samples. The diluted urine samples were spiked with metribuzin at 4 levels and extracted with recoveries ranging from 93.82 to 97.84% and the relative standard deviation (RSD) less than 4.8%.

Selective detection of chloramphenicol based on molecularly imprinted solid-phase extraction in seawater from Jiaozhou Bay, China

This study highlights an efficient sample pre-treatment method for preconcentration and detection of chloramphenicol in marine water using molecularly imprinted solid-phase extraction (MISPE). Chloramphenicol molecularly imprinted microspheres were prepared and evaluated on the base of morphology, capacity and selectivity. The imprinted microspheres exhibited specific recognition and high retention capability to chloramphenicol and were applied as special solid-phase extraction adsorbents. An off-line MISPE protocol has been optimized and a creative analytical method coupled to HPLC-DAD was successfully developed for the cleanup and determination of chloramphenicol in seawater samples. Method performance was satisfactory with recoveries ranging from 81 to 90% and relative standard deviation (RSD) was <4.93% (n = 3). Accuracy of the method was assessed at three spiking concentration levels and the limit of detection was 5 ng L−1. Finally, five seawater samples from Jiaozhou Bay of China were determined and the results showed that there was no chloramphenicol detected.

Development and validation of a QuEChERS method for the analysis of 5-nitroimidazole traces in infant milk-based samples by ultra-high performance liquid chromatography-tandem mass spectrometry

QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) methodology in combination with UHPLC–MS/MS is proposed for the determination of 5-nitroimidazole (5-NDZ) residues in infant milk-based products. Chromatographic separation was accomplished in a C18 Zorbax Eclipse Plus RRHD (50 × 2.1 mm, 1.8 μm) column under gradient elution conditions. Mobile phase consisted of 0.025% (v/v) aqueous formic acid (eluent A) and MeOH (eluent B), and was supplied at a flow rate of 0.5 mL/min. Under these conditions, eleven 5-NDZs including three metabolites were separated in less than 4 min. A novel QuEChERS method was optimized, and primary-secondary amine (PSA) sorbent was selected as clean-up agent. In addition, the proposed QuEChERS procedure was compared with other sample preparation methodologies, which are usually used in the analysis of 5-NDZs, namely solid phase extraction (SPE) using mixed cation exchange (MCX) cartridges and molecularly imprinted solid phase extraction (MISPE). Method comparison was carried out in terms of process efficiency, which includes matrix effect and extraction recovery. Higher process efficiency was generally achieved for QuEChERS and MISPE than for SPE. However, matrix effect was more significant for the non-selective QuEChERS method than for the selective MISPE. Higher extraction recoveries (63.2–94.1%) were observed for QuEChERS. The studied methods were validated in terms of linearity, detection limits (CCα), detection capabilities (CCβ) and precision, observing similar performance characteristics independently of the proposed sample treatment. CCα and CCβ ranged between 0.05 and 1.69 μg/L for all analytes and extraction techniques. QuEChERS-UHPLC–MS/MS method was also validated in terms of precision (relative standard deviations <10.3%), trueness (recovery>70.2%) and selectivity according to Regulation 2002/657/EC. It is proposed as a good alternative for the monitoring of 5-NDZ residues in enriched infant-milk based products and other similar milk based-products.

Determination of Ten Macrolide Drugs in Environmental Water Using Molecularly Imprinted Solid-Phase Extraction Coupled with Liquid Chromatography-Tandem Mass Spectrometry.

With the extensive application of antibiotics in livestock, their contamination of the aquatic environment has received more attention. Molecularly imprinted polymer (MIP), as an eco-friendly and durable solid-phase extraction material, has shown great potential for the separation and enrichment of antibiotics in water. This study aims at developing a practical and economical method based on molecularly imprinted solid phase extraction (MISPE) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for simultaneously detecting ten macrolide drugs in different sources of water samples. The MIP was synthesized by bulk polymerization using tylosin as the template and methacrylic acid as the functional monomer. The MIP exhibited a favorable load-bearing capacity for water (>90 mL), which is more than triple that of non-molecularly imprinted polymers (NIP). The mean recoveries of macrolides at four spiked concentration levels (limit of quantification, 40, 100, and 400 ng/L) were 62.6–100.9%, with intra-day and inter-day relative standard deviations below 12.6%. The limit of detection and limit of quantification were 1.0–15.0 ng/L and 3.0–40.0 ng/L, respectively. Finally, the proposed method was successfully applied to the analysis of real water samples.

Effects of (monomer - crosslinker – initiator) composition during non imprinted polymers synthesis for catechin retention

MISPE (molecularly imprinted Solid Phase Extraction) is a separation technique using a solid adsorbent as a principle of MI (molecularly imprinted). Methacrylic acid (MAA) was used as a monomer, ethylene glycol dimethacrylate (EGDMA) as a crosslinker, benzoyl peroxide (BPO) as an initiator and acetonitrile (ACN) as a porogen. Catechin will be used as the template. Thermal and microwave methods were employed in the synthesis method. When analyzed using FTIR spectra, it was found that there were no significant differences between NIP (non-imprinted polymer) resulting from thermal method and that resulting from microwave method. Preparation of polymers by microwave method required 4 mins at 60-65 °C, significantly less than thermal method, that took 60 minutes at the same temperature. The variations of mole ratios of the monomer, the crosslinker, and the initiator were also performed. Based on the FTIR spectra, intensity of some peaks were changed due to the decreases of concentration. The optimum composition for NIP synthesis was MAA: EGDMA: BPO ratio of 5:30:0.5 (in mmole). The TGA curve showed that the NIP sythesized using microwave method experienced mass loss of around 98.50% at 604.8 °C.

Applying molecular modelling and experimental studies to develop molecularly imprinted polymer for domoic acid enrichment from both seawater and shellfish

A highly selective sample cleanup method using molecularly imprinted polymers (MIP) was developed for the enrichment of domoic acid (DA, an amnesic shellfish toxin) from both seawater and shellfish samples. Molecular modelling was firstly applied to screening a suitable functional monomer and optimize the polymer preparation. Theoretical results were in a good agreement with those of the experimental studies. MIP was prepared by precipitation polymerization using 1, 3, 5-pentanetricarboxylic acid and 2-(Trifluoromethyl)acrylic acid as the template molecule and functional monomer, respectively. The morphology and molecular structure of MIP were revealed by scanning electron microscope (SEM) and fourier transform infrared spectroscopy (FTIR), respectively. The obtained MIP showed high affinity and selectivity for DA with binding site numbers of 0.875 mg g−1 and an average association constant of 0.219 L mg−1 evaluated by adsorption experiments. The developed molecularly imprinted solid-phase extraction (MISPE) column achieved satisfied adsorption rate (99.2%) and recovery (71.2%) with relative standard deviation (RSD) less than 1.0%, which is more stable and precise than the C18, SAX, and HLB columns. Finally, the determination method for DA in both seawater and shellfish samples was then successfully established and validated using MISPE coupled with high-performance liquid chromatography-ultraviolet detection (HPLC-UV). The method limit of detection was 20 μg L−1 and 50 μg kg−1 for seawater and shellfish, respectively. This study demonstrates that molecular modelling is a useful tool to screening functional monomer and optimize polymer preparation. It provides an innovative polymer for trace DA monitoring in both seawater and shellfish.

A simple and highly selective molecular imprinting polymer-based methodology for propylparaben monitoring in personal care products and industrial waste waters

In this work, a novel molecularly imprinted polymer (MIP) proposed as solid phase extraction sorbent was developed for the determination of propylparaben (PP) in diverse cosmetic samples. The use of parabens (PAs) is authorized by regulatory agencies as microbiological preservative; however, recently several studies claim that large-scale use of these preservatives can be a potential health risk and harmful to the environment.Diverse factors that influence on polymer synthesis were studied, including template, functional monomer, porogen and crosslinker used. Morphological characterization of the MIP was performed using SEM and BET analysis. Parameters affecting the molecularly imprinted solid phase extraction (MISPE) and elution efficiency of PP were evaluated. After sample clean-up, the analyte was analyzed by high performance liquid chromatography (HPLC). The whole procedure was validated, showing satisfactory analytical parameters. After applying the MISPE methodology, the extraction recoveries were always better than 86.15%; the obtained precision expressed as RSD% was always lower than 2.19 for the corrected peak areas. Good linear relationship was obtained within the range 8–500ngmL−1 of PP, r2=0.99985. Lower limits of detection and quantification after MISPE procedure of 2.4 and 8ngmL−1, respectively were reached, in comparison with previously reported methodologies. The development of MISPE-HPLC methodology provided a simple an economic way for accomplishing a clean-up/preconcentration step and the subsequent determination of PP in a complex matrix. The performance of the proposed method was compared against C-18 and silica solid phase extraction (SPE) cartridges. The recovery factors obtained after applying extraction methods were 96.6, 64.8 and 0.79 for MISPE, C18-SPE and silica-SPE procedures, respectively. The proposed methodology improves the retention capability of SPE material plus robustness and possibility of reutilization, enabling it to be used for PP routine monitoring in diverse personal care products (PCP) and environmental samples.

Flow-batch analysis of clenbuterol based on analyte extraction on molecularly imprinted polymers coupled to an in-system chromogenic reaction. Application to human urine and milk substitute samples

A fully automated spectrophotometric method based on flow-batch analysis has been developed for the determination of clenbuterol including an on-line solid phase extraction using a molecularly imprinted polymer (MIP) as the sorbent.The molecularly imprinted solid phase extraction (MISPE) procedure allowed analyte extraction from complex matrices at low concentration levels and with high selectivity towards the analyte. The MISPE procedure was performed using a commercial MIP cartridge that was introduced into a guard column holder and integrated in the analyzer system. Optimized parameters included the volume of the sample, the type and volume of the conditioning and washing solutions, and the type and volume of the eluent.Quantification of clenbuterol was carried out by spectrophotometry after in-system post-elution analyte derivatization based on azo-coupling using N- (1-Naphthyl) ethylenediamine as the coupling agent to yield a red-colored compound with maximum absorbance at 500nm. Both the chromogenic reaction and spectrophotometric detection were performed in a lab-made flow-batch mixing chamber that replaced the cuvette holder of the spectrophotometer.The calibration curve was linear in the 0.075–0.500mgL−1 range with a correlation coefficient of 0.998. The precision of the proposed method was evaluated in terms of the relative standard deviation obtaining 1.1% and 3.0% for intra-day precision and inter-day precision, respectively. The detection limit was 0.021mgL−1 and the sample throughput for the entire process was 3.4h−1.The proposed method was applied for the determination of CLB in human urine and milk substitute samples obtaining recoveries values within a range of 94.0–100.0%.

Isolation and Purification of Three Analogues from Clematis akebioides by Molecularly Imprinted Solid-Phase Extraction and HSCCC

An efficient strategy of using molecularly imprinted solid-phase extraction and high-speed counter-current chromatography (HSCCC) were established for separation and purification of three analogues from Clematis akebioides for the first time. The three analogues, including 26.30 mg caffeic acid, 84.20 mg p-coumaric acid, and 44.40 mg ferulic acid, were obtained from 200.00 mg of the crude sample. The molecularly imprinted polymer was prepared with caffeic acid as template molecule and acrylamide as functional monomers. The results showed that the caffeic acid and its analogues could be well enriched. Then, the extract was purified by HSCCC using a two-phase solvent system consisting of chloroform/acetonitrile/water/acetic acid (10:5:4:0.0004, v/v) and a continuous sample introduction system was adopted. The three organic acids were identified by 1H-NMR and 13C-NMR.

Analysis of alternariol and alternariol monomethyl ether in foodstuffs by molecularly imprinted solid-phase extraction and ultra-high-performance liquid chromatography tandem mass spectrometry

Molecularly imprinted porous polymer microspheres selective to Alternaria mycotoxins, alternariol (AOH) and alternariol monomethyl ether (AME), were synthesized and applied to the extraction of both mycotoxins in food samples. The polymer was prepared using 4-vinylpiridine (VIPY) and methacrylamide (MAM) as functional monomers, ethylene glycol dimethacrylate (EDMA) as cross-linker and 3,8,9-trihydroxy-6H-dibenzo[b,d]pyran-6-one (S2) as AOH surrogate template. A molecularly imprinted solid phase extraction (MISPE) method has been optimized for the selective isolation of the mycotoxins from aqueous samples coupled to HPLC with fluorescence (λex=258nm; λem=440nm) or MS/MS analysis. The MISPE method was validated by UPLC–MS/MS for the determination of AOH and AME in tomato juice and sesame oil based on the European Commission Decision 2002/657/EC. Method performance was satisfactory with recoveries from 92.5% to 106.2% and limits of quantification within the 1.1–2.8µgkg−1 range in both samples.

Molecularly Imprinted Polymers (MIP) for Selective Solid Phase Extraction of Celecoxib in Urine Samples Followed by High Performance Liquid Chromatography

In this study, for the analysis of human urine samples, a novel method explained for the determination of celecoxib, a nonsteroidal anti-inflammatory drug (NSAID), using molecularly imprinted solid-phase extraction (MISPE) coupled with high-performance liquid chromatography (HPLC). The synthesis of the MIP was performed by precipitation polymerization in methacrylic acid (MAA), ethylene glycol dimethacrylate (EGDMA), chloroform, 2,2′-azobisisobutyronitrile (AIBN) and celecoxib as the functional monomer, cross-linker monomer, solvent, initiator and target drug, respectively. The celecoxib imprinted polymer was utilized as a specific sorbent for the solid phase extraction (SPE) of celecoxib from samples. The molecularly imprinted polymer (MIP) performance was compared with the synthesized non-molecularly imprinted polymer (NIP). Scanning electron microscopy (SEM), FT-IR spectroscopy, UV-VIS spectrophotometry and thermogravimetric analysis (TGA/DTG) were used for characterizing the synthesized polymers. Moreover, the MISPE procedure parameters such as pH, eluent solvent flow rate, eluent volume and sorbent mass that probably influence the extraction process have been optimized to achieve the highest celecoxib extraction efficiency. The relative standard deviation (RSD %), recovery percent, limit of detection (LOD) and limit of quantification (LOQ) of this proposed method were 1.12%, 96%, 8 µg L -1 and 26.7 µg L -1 , respectively. The proposed MISPE-HPLC-UV method can be used for the separation and enrichment of trace amounts of celecoxib in human urine and biological samples.

Subcritical water extraction combined with molecular imprinting technology for sample preparation in the detection of triazine herbicides

A selective, environmentally friendly, and cost-effective sample extraction method based on a combination of subcritical water extraction (SWE) and molecularly imprinted solid-phase extraction (MISPE) was developed for the determination of eight triazine herbicides in soil samples by liquid chromatography-tandem mass spectrometry (LC–MS/MS). In SWE, the highest extraction yields of triazine herbicides were obtained under 150°C for 15min using 20% ethanol as the organic modifier. Addition of MIP during SWE increased the extraction efficiency, and using MIP as a selective SPE sorbent improved the enrichment capability. Soil samples were treated with the optimized extraction MIP/SWE-MISPE method and analyzed by LC–MS/MS. The novel technique was then applied to soil samples for the determination of triazine herbicides, and better recoveries (78.9%–101%) were obtained compared with using SWE-MISPE (30%–67%). Moreover, this newly developed method displayed good linearity (R2>0.99) and precision (2.7–9.8%), and low enough detection limits (0.4–3.3μgkg−1). This combination of SWE and MIP technology is a simple, effective and promising method to selectively extract class-specific compounds in complex samples.

Selective isolation of gonyautoxins 1,4 from the dinoflagellate Alexandrium minutum based on molecularly imprinted solid-phase extraction

Gonyautoxins 1,4 (GTX1,4) from Alexandrium minutum samples were isolated selectively and recognized specifically by an innovative and effective extraction procedure based on molecular imprinting technology. Novel molecularly imprinted polymer microspheres (MIPMs) were prepared by double-templated imprinting strategy using caffeine and pentoxifylline as dummy templates. The synthesized polymers displayed good affinity to GTX1,4 and were applied as sorbents. Further, an off-line molecularly imprinted solid-phase extraction (MISPE) protocol was optimized and an effective approach based on the MISPE coupled with HPLC-FLD was developed for selective isolation of GTX1,4 from the cultured A. minutum samples. The separation method showed good extraction efficiency (73.2–81.5%) for GTX1,4 and efficient removal of interferences matrices was also achieved after the MISPE process for the microalgal samples. The outcome demonstrated the superiority and great potential of the MISPE procedure for direct separation of GTX1,4 from marine microalgal extracts.

Synthesis and application of molecularly imprinted polymer for highly selective solid phase extraction trace amount of sotalol from human urine samples: Optimization by central composite design (CCD)

A novel method is described for trace determination of sotalol, a β-blocker drug, using molecularly imprinted solid-phase extraction (MISPE) coupled with high-performance liquid chromatography with UV detection (HPLC/UV). The synthesis of the molecularly imprinted polymer was performed using acrylamide, ethylene glycol dimethacrylate, dimethylformamide, 2,2′-azobisisobutyronitrile and sotalol as a functional monomer, cross-linker monomer, solvent, initiator, and target drug, respectively. Scanning electron microscopy and Fourier transform infrared spectroscopy were used for characterizing the synthesized polymers. Also, a central composite design under response surface methodology and chemometrics applied to investigate and optimize the molecularly imprinted solid-phase extraction procedure parameters such as pH, loading and eluent solvent flow-rate, eluent solvent volume and sorbent mass, that probably influence the extraction process, to achieve the highest sotalol extraction efficiency. Batch rebinding capacity of sotalol was determined from the derived Langmuir isotherm and was found to be 20.08 mg/g. At above specified conditions, the proposed MISPE-HPLC/UV method used for the separation of trace amounts of sotalol in human urine samples with acceptable high recoveries (97–102%) and RSD% lower than 5%. The limit of detection and limit of quantification of the method were 0.01 and 0.04 μg/mL, respectively.

Molecularly imprinted solid-phase extraction coupled with LC-APCI-MS-MS for the selective determination of serum cholesterol.

The assessment of selective molecularly imprinted solid-phase extraction (MISPE) for clean-up and extraction of cholesterol (CHO) from bovine and human serum samples was evaluated. Two molecular imprinted polymers (MIP) based on organic and inorganic/organic (hybrid) materials were obtained and compared regarding recovery and selectivity toward CHO. Optimum chromatographic separation between the CHO and its isobaric compound lathosterol (LATHO) has been achieved within 15min using an Agilent Poroshell 120 EC-C18 column (120mm×3.0mm, 2.7μM) and mobile phase consisting of acetonitrile:methanol (8:2, v/v) at a flow rate of 0.6mLmin-1 . Mass spectrometry detection was operated in atmospheric pressure chemical ionization (APCI) (+) mode and the SIM transitions [M-H2 O+H]+ for CHO and LATHO were 364.1 → 161.2 → 95.2 and 364.1 → 95.1 → 81.1m/z, respectively. The sample preparation could be accomplished within 1h, and the matrix effect on the MS signal after sample pretreatment did not interfere in the analyses. The method provided a good linear range (0.013-312μM.) with coefficients of determination of R2 >0.99, substantial sensitivity (limits of detection of 6.5nM), good recovery (∼90%), high reproducibility (intraday and interday relative standard deviations less than 15%) and satisfactory accuracy (relative error ranged from -13.46% to 11.54%). The organic MIP showed superior performance compared with the hybrid. Finally, the MISPE procedure followed by LC-APCI-MS-MS analysis showed their suitable applicability to examine CHO and LATHO in serum samples.