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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-6 H -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 (λ ex = 258 nm; λ em = 440 nm) 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 1.1–2.8 µg kg −1 range in both samples.

Tenuazonic acid (TeA) is a common mycotoxin produced by Alternaria species found in various foodstuffs. Herein, we describe the preparation of porous molecularly imprinted polymer (MIP) microspheres doped with Eu(III), for selective fast analysis of TeA in rice extracts. The TeA template, bearing a β-diketone moiety, is a good Eu(III)-chelating antenna ligand that can be selectively captured in the MIP cavities and detected by observing the “turned-on” sensitized luminescence of the Eu(III) ions at 615 nm (λex 337 nm). A MIP library was prepared at small scale using diethyl allylmalonate (DEAM) or allyl acetoacetate as functional monomers, mixed in different mole ratios with the template and ethylene glycol dimethacrylate (EDMA) as cross-linker. The screening allowed selection of poly(DEAM-co-EDMA) with Eu(III) as luminogenic metal center for the sensor development. Under the optimized conditions, a linear response to TeA in the 1.7–20 μg mL−1 range, with a detection limit of 0.5 μg mL−1, was obtained. The Eu(III)-doped MIP for TeA showed very little or no cross-recognition of other mycotoxins present in foodstuff such as alternariol, β-zearalenol and cyclopiazonic acid, even containing the same recognition moiety. The MIP-based optosensor was successfully applied to the analysis of rice extracts spiked with TeA, and the results were confirmed by HPLC-DAD.

This paper describes the synthesis of novel molecularly imprinted polymer (MIP) micro-beads for the selective extraction (MISPE) of six fluoroquinolone (FQ) antibiotics (enrofloxacin, ciprofloxacin, lomefloxacin, danofloxacin, sarafloxacin and norfloxacin) from chicken muscle samples and further analysis by high-performance liquid chromatography (HPLC) with fluorescence (FLD) or mass spectrometry (MS) detection. A combinatorial screening approach has been applied to select the optimal functional monomer and cross-linker formulation for polymer synthesis. The MIP prepared using enoxacin (ENOX) as the template - a mixture of methacrylic acid (MAA) and trifluoromethacrylic acid (TFMAA) as functional monomers and ethylene glycol dimethacrylate (EDMA) as the cross-linker - showed superior FQ recognition properties than the rest of the materials generated. MIP spherical particles were prepared using silica beads as sacrificial scaffolds. The polymers were packed in solid phase extraction (SPE) cartridges. The optimized MISPE-HPLC method allows the extraction of the antimicrobials from aqueous samples followed by a selective washing with acetonitrile/water (0.005% TFA, pH=3.0), 20:80 (v/v) and elution with 5% trifluoroacetic acid in methanol. Optimum MISPE conditions led to recoveries of the target FQs in chicken muscle samples ranging between 68 and 102% and precisions in the 3-4% range (RSD, n=18). The method has been validated according to European Union Decision 2002/657/EC, in terms of linearity, accuracy, precision, selectivity, decision limit (CCα) and detection capability (CCβ) by HPLC-FLD and HPLC-MS/MS. The limits of detection were improved using HPLC-MS/MS analysis and ranged between 0.2 and 2.7μgkg(-1) (S/N=3) for all the FQs tested.

This paper reports a sensitive, highly selective flow injection (FI) method for the chemiluminescence-based determination of enrofloxacin (ENRO), a fluoroquinolone (FQ) antibiotic, in natural water samples. The detection principle is the on-line monitored photoreaction of tris(1,10-phenantroline)ruthenium(II) [Ru(phen)32 +] with peroxydisulphate ion to give Ru(phen)33 +, which is then reduced by the antimicrobial producing the chemiluminescence (CL) signal. The low selectivity of the CL reaction required using solid-phase extraction with molecularly imprinted polymers (MISPE) in combination with the FI-CL system. Fluoroquinolone-selective MIP beads were obtained by acid etching of silica/MIP composites and packed into SPE cartridges to clean-up and preconcentrate samples prior injection into the FI-CL system. Various parameters influencing the CL signal intensity including pH, flow rate, and Ru(phen)32 + and peroxydisulphate concentrations, were optimized. The variables affecting the extraction efficiency of the polymers were also optimized in order to minimize non-specific interactions and enable the selective uptake of the antibiotics from real samples. CL measurements made over the pH range 3.8–4.2 allowed the selective determination of enrofloxacin, and measurements at pH 4.8–5.8 the quantitation of total FQs (enrofloxacin, ciprofloxacin, norfloxacin, sarafloxacin, lomefloxacin and danofloxacin). The limit of detection for enrofloxacin was 0.27 μg L− 1 when 10 mL water samples were preconcentrates. The proposed method was used to determine trace amounts of FQs in mineral and tap water, and also in water samples from the river Quibu (Cuba), all with good recoveries: 84–119% (RSD 2.1–9.3%, n = 3) for samples fortified with enrofloxacin at concentrations from 4 to 40 μg L− 1. The method was validated by HPLC with fluorescence detection.

A novel and simple method for the selective cleanup and preconcentration of fluoroquinolone antibiotics in environmental water samples has been developed using molecularly imprinted polymer solid-phase extraction (MISPE). The molecularly imprinted polymer (MIP) has been prepared using enrofloxacin (ENR) as the template and a stoichiometric quantity of urea-based functional monomer to target the single oxyanionic moieties in the template molecule. The selectivity of the material for enrofloxacin, and structurally related and non-related compounds, has been evaluated using it as stationary phase in liquid chromatography. The novel polymer and the corresponding non-imprinted material (NIP) have been characterised using nitrogen adsorption-desorption isotherms and scanning electron microscopy. Various parameters affecting the extraction efficiency of the materials in the MISPE procedure were evaluated in order to achieve optimal preconcentration and to reduce non-specific interactions. The optimized MISPE/HPLC with fluorescence detection (FLD) method allows direct extraction of the antibiotics from the aqueous samples followed by a selective washing with acetonitrile/water (0.1M 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid (HEPES) buffer, pH 7.5) (10/90, v/v) and elution with 2% trifluoracetic acid in methanol. Good recoveries and precision, ranging between 66 and 100% (RSD: 2-12%, n=3) for danofloxacin, enrofloxacin, oxolinic acid and flumequine, and moderate recoveries (15-40%, RSD 4-9%, n=3) for norfloxacin, ciprofloxacin, lomefloxacin and sarafloxacin, have been obtained for river water samples fortified with 0.50, 0.75 and 1.0microgL(-1) of all the antibiotics. The method detection limits ranged between 0.01 and 0.30microgL(-1) for all the antibiotics tested, when 100mL water samples were processed. The results demonstrate the applicability of the optimized method for the selective extraction of fluoroquinolones in environmental water samples at the ngL(-1) level.

A molecularly imprinted polymer (MIP)-based optode has been developed for zearalenone (ZON) mycotoxin analysis. The automated flow-through assay is based on the displacement of tailor-made highly fluorescent tracers by the analyte from a MIP prepared by UV irradiation of a mixture of cyclododecyl 2,4-dihydroxybenzoate (template, ZON mimic), 1-allyl piperazine (functional monomer), trimethylolpropane trimethacrylate (crosslinker) and 2,2′-azobisisobutyronitrile in acetonitrile (porogen). Three fluorescent analogues of ZON, namely 2,4-dihydroxybenzoic acid 2-[methyl(7-nitro-benzo[1,2,5]oxadiazol-4-yl)amino]ethyl ester (NBDRA), 2,4-dihydroxy- N -pyren-1-ylmethylbenzamide (PMRA) and of 2,4-dihydroxybenzoic acid 2-[(pyrene-l-carbonyl)amino] ethyl ester (PARA), have been molecularly engineered for the assay development. The pyrene-containing tracers also inform on the characteristics of the microenvironment of the MIP binding sites. PARA has been finally selected to optimize the ZON displacement fluorosensor, that shows a limit of detection of 2.5 × 10 −5 M in acetonitrile. A positive cross-reactivity has been found for β-zearalenol, but not for resorcinol, resorcylic acid, 17β-estradiol, estrone or bisphenol-A.

Molecularly imprinted polymers (MIPs) with selective recognition properties for zearalenone (ZON), an estrogenic mycotoxin, and structurally related compounds have been prepared using the non-covalent imprinting approach. A rationally designed ZON analogue, cyclododecyl 2,4-dihydroxybenzoate (CDHB), that exhibits resemblance to ZON in terms of size, shape and functionality has been synthesized and used as template for MIP preparation instead of the natural toxin. Several functional monomers have been evaluated to maximize the interactions with the template molecule during the polymerization process. The polymer material prepared with 1-allylpiperazine (1-ALPP) as functional monomer, trimethyl trimethacrylate (TRIM) as cross-linker and acetonitrile as porogen (in a 1:4:20 molar ratio) displayed superior binding capacities than any other of the MIPs tested. Selectivity of this material for ZON and structurally related and non-related compounds has been evaluated using it as stationary phase in liquid chromatography. Our results demonstrate that the imprinted polymer shows significant affinity in the porogenic solvent for the template mimic (CDHB) as well as for the ZON and other related target metabolites in food samples, dramatically improving the performance of previously reported MIPs for ZON recognition. Therefore, MIPs can be an excellent alternative for clean-up and preconcentration of the mycotoxin in contaminated food samples.

A fast and accurate method for the determination of zearalenone (ZON) and α-zearalenol (α-ZOL) in ground wheat samples has been optimised using accelerated solvent extraction (ASE) and liquid chromatography (LC) with fluorescence detection. The effects of the experimentally controllable ASE parameters (solvent composition, temperature, pressure, number of extraction cycles and sample cell size) on the extraction efficiencies of the target analytes have been investigated using wheat samples fortified at the ng g−1 level. The optimum extraction conditions were obtained using a 11 mL ASE cell, methanol/acetonitrile (50:50 v/v) as the extraction solvent, 1500 psi, 50 °C, a 5 min static time and a 60% flush volume. The extracted samples were analysed using LC with fluorescence detection (λexc=271 and λem=452 nm). The stationary phase was a polar endcapped C18 column and acetonitrile/methanol/water 10/55/35 (v/v/v, 15 mM ammonium acetate) at a flow rate of 1.0 mL min−1 was used as the mobile phase. The injection volume was set at 8 μL. Mean recovery rates of 98.4% for α-ZOL (RSD