Molecularly Imprinted Solid-phase Extraction Cartridge Research Articles

Valorization of potato peel waste: Recovery of p-hydroxy benzoic acid (antioxidant) through molecularly imprinted solid-phase extraction.

Solid waste management of the potato peels, generated during the processing of potatoes, can be done sustainably by adding value to the peel waste. Peels contains polyphenols, which serve as a defense mechanism against foreign pathogens in plants and have a variety of pharmacological properties such as antioxidant and anti-carcinogenic properties. However, specific segregation of any one polyphenol from waste can be challenging due to its complex matrix and low concentration of the targeted polyphenol. This work presents a way to combat this challenge through molecularly imprinted solid-phase extraction (MISPE) using customized graphene oxide-based molecularly imprinted composite (GOMIP) as sorbent for the selective recovery of p-hydroxy benzoic acid (P-HA) (antioxidant used in food industries), from potato peels for the effective valorization of peels. Various parameters such as flow rate, vacuum manifold pressure, conditioning solvent, washing solvent, and elution solvent were optimized for effective segregation of targeted P-HA. The imprinting factor of 2.14, obtained using breakthrough curves for GOMIP and control (graphene oxidebased non-imprinted composite-GONIP) sorbent under optimized condition, indicated the ability of the sorbent GOMIP to recover P-HA from the extract of potato peels. Reusability and selectivity studies were performed for GOMIP sorbent using the real sample [potato peels extract (PPE)]. 77.44% recovery for P-HA was exhibited by the GOMIP sorbent in the MISPE cartridge as determined using HPLC. MISPE with customized GOMIP sorbent can be a sustainable approach to valorize the potato peel solid waste.

Efficient Recognition and Determination of Carbamazepine and Oxcarbazepine in Aqueous and Biological Samples by Molecularly Imprinted Polymers

A molecularly imprinted polymer (MIP) of carbamazepine (CBZ) was synthesized so as to facilitate the selective extraction of CBZ from aqueous and bio-samples by using a non-covalent imprinting approach. Synthesized materials were characterized with Fourier-transform infrared spectroscopy and scanning electron microscopy studies. The imprinted polymer was evaluated and applied as a sorbent for solid-phase extraction (SPE) coupled with HPLC-UV to detect CBZ and its metabolite oxcarbazepine (OXC). The optimal conditions for molecularly imprinted SPE (MISPE) consist of the cartridge conditioning using methanol followed by triply distilled water, loading the aqueous sample and elution by methanol-acetic acid (9 : 1, v/v). The selectivity and sensitivity for pre-concentration and separation of the target analytes were studied in details, in order to build a simple and sensitive method which can act as a potential analytical strategy to monitor CBZ and OXC in the environmental and biological samples. The developed method exhibited a wide linear range (1–500 μg/L), good linearity (R2 > 0.990), and relative standard deviation <3%. The molecular recognition properties of the MIP gave rise to good recoveries for CBZ (87–98%) and OXC (72–78%) when spiked aqueous and bio-samples were percolated through the MISPE procedure. The limit of detection for CBZ and OXC were 0.488 and 0.515 μg/L, respectively. Moreover, each MISPE cartridge, when investigated for reusability test, displayed excellent recoveries for CBZ (98–94%) with enhanced reusability (10 cycles).

Selective extraction and concentration of mebendazole in seawater samples using molecularly imprinted polymer as sorbent

A high selective pre-treatment method for the extraction and analysis of mebendazole in environmental water samples was developed based on molecularly imprinted solid-phase extraction (MISPE). The mebendazole imprinted polymers were synthesized in acetonitrile using methacrylic acid and ethylene glycol dimethacrylate as functional monomer and cross-linker respectively. The imprinted materials showed high adsorption ability for mebendazole and were applied as special solid-phase extraction sorbents for selective separation of mebendazole. An off-line MISPE procedure was developed for the purification and enrichment of mebendazole from natural seawater samples prior to high-performance liquid chromatography analysis. The recoveries of spiked seawater on the MISPE cartridges were from 83.0% to 90.6%, and the values of the relative standard deviation were in the range of 2.78–4.13% (n=3). The satisfied results showed that this pre-treatment methodology for extracting mebendazole in seawater was simple and effective.

Micelle enhanced and terbium sensitized spectrofluorimetric determination of danofloxacin in milk using molecularly imprinted solid phase extraction

An efficient molecularly imprinted solid phase extraction (MISPE)-spectrofluorimetric method was developed to sensitively determine danofloxacin (DAN) in milk samples. Solid phase extraction procedure using MISPE cartridges was first performed on milk samples and then spectrofluorimetric determination was done at 546nm using an excitation wavelength of 285nm in presence of terbium and sodium dodecyl benzene sulfonate (SDBS). It was found that SDBS significantly enhanced the fluorescence intensity of the DAN–Tb3+ complex. Various factors affecting the fluorescence intensity of DAN–Tb3+–SDBS system were studied and conditions were optimized. The enhanced fluorescence intensity of the system (ΔF) showed a good linear relationship with the concentration of DAN over the range of 8.4×10−9–3.4×10−7molL−1 with a correlation coefficient of 0.9996. The detection limit was determined as 2.0×10−9molL−1 and the limit of quantification was determined as 6.5×10−9molL−1. The MISPE-spectrofluorimetric procedure was successfully applied to the determination of DAN in milk samples. The method is simple, rapid, sensitive and allows interference free determination of DAN in complex fluorescent matrices like milk. The method can be used to determine whether the DAN residues in milk exceed MRLs or not.

Molecularly imprinted solid-phase extraction for the selective HPLC determination of ractopamine in pig urine

A method was developed for the determination of ractopamine in pig urine using molecularly imprinted solid-phase extraction (MISPE) as the sample clean-up technique combined with high-performance liquid chromatography. The molecularly imprinted polymer (MIP) was synthesized in acetonitrile-triethylamine system using ractopamine (RAC) as the template and acrylamide as the monomer. The binding capacity of the polymer toward RAC was found to be about 2.57 mg of ractopamine/g of polymer. The optimal procedures for MISPE consisted of conditioning with 3 mL methanol, equilibrating with 3 mL of water, loading volume of <10 mL of aqueous sample (pH 7), washing with 3 mL water and 3 mL methanol, and eluting with 5 mL of 5% ammonia in methanol. In the four spiked samples with the levels of 0.01, 0.1, 1.0 and 5.0 μg/mL, the mean recoveries of analyte on the MIP were higher than 90% with relative standard deviation <10%, and significant differences between imprinted and non-imprinted materials were observed. The MIP selectivity was evaluated by checking 11 drugs with similar and different molecular structures to that of RAC. The characteristics of three-dimensional cavities and hydrogen bond interaction were regarded as the main factors that dominated the retention of RAC on the MISPE cartridge.

Molecularly imprinted solid‐phase extraction coupled with HPLC for the selective determination of monobutyl phthalate in bottled water

A molecularly imprinted polymer (MIP) was prepared using monobutyl phthalate as template. The synthesis was optimized by using different porogens and functional monomers. The MIP was used as a selective sorbent in molecularly imprinted solid-phase extraction (MIP-SPE) for pre-concentration and determination of monobutyl phthalate (mBP) from the bottled water. The difference in recognition selectivity of the polymer columns was observed in HPLC system, and the effect of the mobile phase on the performance of MIP columns was also investigated. Control of the MIP-SPE process is seen as important in helping to facilitate the selective extraction of mBP from water samples. Thereafter, the choice of washing solvent, eluting solvent amount, pH of loading sample, flow rate of loading solution and the loading sample volume was presented. The optimized procedure was described as follows: 25 mL spiked aqueous solution was percolated through the MIP-SPE cartridge at the flow rate of 1.5 mL/min. After rinsing with acetonitrile/methanol mixture (1:1, v/v), the bound analyte was desorbed with 3 mL methanol. The developed MIP-SPE method was demonstrated to be applicable for the analysis of mBP in the bottled water.

Molecularly imprinted solid-phase extraction for determination of tilmicosin in feed using high performance liquid chromatography

A simple, sensitive and reproducible molecularly imprinted solid-phase extraction (MISPE) coupled with high performance liquid chromatographic method was developed for monitoring tilmicosin in feeds. The polymers were prepared using tylosin as mimic template molecule, methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linking monomer, and chloroform as a solvent by bulk polymerization. Under the optimum MISPE conditions, the novel polymer sorbent can selectively extract and enrich tilmicosin from variety of feeds. The MISPE cartridge was better than non-imprinted, C 18 and HLB cartridges in terms of both recovery and precision. Mean recoveries of tilmicosin from five kinds of feeds spiked at 1, 10 and 50 mg kg −1 ranged from 76.9% to 95.6%, with intra-day and inter-day relative standard deviation less than 7.6%. The linearity was ranged from 1.0 to 100 mg L −1 for matrix standard solution ( r = 0.9990). The limit of detection was approximately 0.35 mg kg −1 and the limit of quantification was approximately 0.98 mg kg −1. There was cleaner chromatogram by using MISPE than C 18 and HLB SPE.

2,4-Dimethylphenol imprinted polymers as a solid-phase extraction sorbent for class-selective extraction of phenolic compounds from environmental water

A molecularly imprinted polymer (MIP) was prepared using 2,4-dimethylphenol (2,4-DMP) as template. The synthesis is optimized by using three different porogens, chloroform, acetonitrile and toluene. The MIP was used as a class-selective sorbent in molecularly imprinted solid-phase extraction (MIP-SPE) for pre-concentration and determination of phenolic compounds from the environmental water. The difference in recognition selectivity of the polymer columns was observed in HPLC system. The variables affecting the extraction efficiency of MIP-SPE procedure were systematically investigated to facilitate the class-selective extraction of phenols from spiked water samples. The spiked aqueous solution was adjusted to pH 6.0 before being percolated through the MIP-SPE cartridge at the flow rate of 0.5mLmin(-1). After rinsing with dichloromethane, the bound phenolic compounds were desorbed with acetonitrile containing 5% aqueous ammonia. The developed MIP-SPE method was demonstrated to be applicable to the analysis of phenolic compounds in the environmental water.

Novel cyromazine imprinted polymer applied to the solid-phase extraction of melamine from feed and milk samples

A water compatible molecularly imprinted polymer (MIP) using cyromazine as a mimic template, methacrylic acid as the functional polymer and ethylene glycol dimethacrylate as the cross-linker was synthesized and used to extract melamine from feed and milk samples via a molecularly imprinted solid-phase extraction (MISPE) protocol. Optimum retention of melamine on the MISPE cartridge was achieved using methanol, and the interferences in the samples were effectively washed out. The binding capacity of the polymer toward melamine was found to be about 500 μg of melamine/g of polymer. The recoveries of 2 μg and 20 μg melamine standard spiked into water extract of blank feeds and milk samples were between 83.4% and 103%, with relative standard deviation <5.6%. The cyromazine-MIP demonstrated high cross-reactivity for melamine and low affinity to cyanuric acid. The ionic bond interaction was regarded as the main factors that dominated the retention of the melamine on the MISPE cartridge.

Determination of clenbuterol in bovine liver by combining matrix solid-phase dispersion and molecular imprinted solid-phase extraction followed by liquid chromatography/electrospray ion trap multiple-stage mass spectrometry.

Matrix solid-phase dispersion (MSPD) is a new sample pretreatment for solid samples. This technique greatly simplifies sample pretreatment but, nonetheless, the extracts often still require an extra cleanup step that is both laborious and time-consuming. The potential of combining MSPD with molecularly imprinted solid-phase extraction (MISPE) was investigated in this study. Liver samples were ground in a mortar with C18 sorbent and the homogenized mixture packed into an SPE cartridge and placed on top of a MISPE cartridge. Subsequently, clenbuterol was eluted from the MSPD cartridge onto the MISPE cartridge using acetonitrile containing 1% acetic acid. The ability of the molecularly imprinted polymer to selectively adsorb analyte in acetonitrile was exploited for re-extracting clenbuterol directly from this acetonitrile extract via the double cartridge tandem system. The analyte was eluted from the MISPE cartridge using acidified methanol. A clear eluate was obtained, which was subsequently evaporated, redissolved, and analyzed by HPLC electrochemical detection (ECD) or ion trap mass spectrometry (LC/IT-MS). The MISPE cartridge used in this study was imprinted using bromoclenbuterol, a structural analogue of clenbuterol, as the template. These MISPE cartridges showed excellent stability. The complete extraction procedure was rapid, and recoveries exceeded 90% for the target analyte. The method detection limit for the LC/IT-MS procedure was < 0.1 microg/kg. This method, therefore, satisfies the stringent requirements of European Union regulation EEC 2377/90.