Analytical methods for the determination of bisphenol A in food.

Food constitutes the primary route for human exposure to bisphenol A (BPA), one of the highest volume chemicals produced worldwide. The estrogenic properties of BPA, its wide dispersive use and the recent extensive literature describing low-dose BPA effects in animals, have raised concerns about its possible adverse effects on human health. A reliable health risk assessment of BPA relies basically on its unambiguous identification and accurate quantification in food, and the aim of the present review is to give an overview of the analytical methods reported so far for the determination of BPA in these matrices. Emphasis is placed on the main strategies developed for sample treatment, which usually consists of several laborious and time-consuming steps in order to achieve the required sensitivity and selectivity. Separation, identification and quantitation of BPA is today reliably made with mass spectrometric methods, namely liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS), and thus main attention is devoted to these techniques, but other methods using LC coupled to fluorescence or electrochemical detection, as well as immunochemical methods are also covered. Recent and expected future developments are discussed.

Potential of supramolecular solvents for the extraction of contaminants in liquid foods.

Amphiphile-based supramolecular solvents (ASSs), which are water immiscible liquids consisting of supramolecular aggregates in the nano- and micro-scale regimes dispersed in a continuous phase, were assessed for the extraction of trace contaminants in liquid foods. The ASS selected was made up of reversed micelles of decanoic dispersed in tetrahydrofuran (THF)-water and the contaminants used as a model were bisphenol A (BPA), ochratoxin A (OTA) and benzo(a)pyrene (BaPy). The influence of matrix components on the extractant solvent production, extraction recoveries and actual concentration factors was investigated by using commercial foods such as wine and wine-based products, beer, soft drinks and tea and coffee brews, and/or aqueous synthetic solutions containing specific food matrix components. The method involved the addition of decanoic acid (80mg) and THF (0.8-1.7mL) to the food sample (15mL), stirring of the mixture for 5min, centrifugation for 10min and analysis of 10-20microL of the extract by liquid chromatography coupled to fluorimetry for OTA and BaPy or to mass spectrometry for BPA. No clean-up of the crude extracts was required for any of the samples analysed. The quantification limits for the contaminants (14-31ngL(-1), 0.37-0.39ngL(-1) and 562-602ngL(-1) for OTA, BaPy and BPA, respectively) were far below their respective European legislative threshold limits. Recoveries for food samples were in the ranges 79-93%, 90-96% and 78-82% for OTA, BaPy and BPA, respectively, with relative standard deviations ranging from 1 to 7%, and actual concentrations factors between 65 and 141. The methods developed were applied to the determination of the target compounds in a variety of commercial foods. OTA was found in vinegar, must and beer samples, the concentrations ranging from 92 to 177ngL(-1), BaPy was quantified in samples of tea and coffee at concentrations between 1.5 and 16.6ngL(-1) whereas BPA was detected in two canned soft drinks and quantified in one of them (tea beverage) at a level of 2.3microgL(-1).

Single-drop coacervative microextraction of organic compounds prior to liquid chromatography. Theoretical and practical considerations.

Coacervates made of surfactant aggregates, namely aqueous and reverse micelles and vesicles, were firstly used as solvents in single-drop microextraction (SDME) and proposed for the extraction and concentration of chlorophenols prior to liquid chromatography. The formation of coacervate drops in the needle tip of conventional microsyringes depended on the type of intermolecular forces established between the surfactant headgroups making up the supramolecular aggregates; hydrogen bond interactions were strong enough to permit the formation of spherical drops. Stability of 1-50 microL coacervate drops was achieved by introducing the microsyringe needle tip in a PTFE rod, the end of which had been machined out with a heated flanging-tool to get circular flanges (diameters in the range 3.5-6 mm). The parameters affecting the efficiency of single-drop coacervative microextraction (SDCME) were investigated using vesicular coacervates as a solvent and 2-chlorophenol (CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP) as model analytes. Coacervative microextraction dynamics fit to the general rate equation of liquid-liquid extraction. The effect of variables such as extraction time, drop volume, stirring rate, pH and temperature, on the extraction of chlorophenols was similar to that described for organic solvent drops. Electrolyte concentrations above 0.1 M caused drop instability. Under the optimum conditions, detection limits were in the range 0.1-0.3 microg L(-1). The relative standard deviation was between 4.3 and 5.6 at 20 microg L(-1) spiked level. The method was applied to the determination of the four chlorophenols in wastewater, superficial water from a reservoir and groundwater and the recoveries were in the range 79 and 106% at 5-20 microg L(-1) spiked level.

Determination of priority carcinogenic polycyclic aromatic hydrocarbons in wastewater and surface water by coacervative extraction and liquid chromatography-fluorimetry.

The US Environmental Protection Agency (EPA) and the European Union (EU) have set restrictive limits for priority carcinogenic polycyclic aromatic hydrocarbons (CPAHs) in surface waters (EPA 3.8 ng L(-1) and EU 2-100 ng L(-1)) in order to protect aquatic life and human health. Currently, methods meeting these sensitivity criteria are not suitable for routine analysis of CPAHs. Here, we present a simple, rapid and low-cost method for the routine monitorization of these pollutants in aquatic environments based on their extraction with coacervates of decanoic acid reverse micelles in the nano- and microscale, and determination by liquid chromatography-fluorimetry (LC-FL). The method involves the stirring of filtered aqueous samples (36 mL) with 4 mL of THF containing 70 mg of decanoic acid for 5 min, its centrifugation for 10 min and the analysis of 20 microL of the resulting coacervate containing the CPAHs by LC/FL. The method is robust, the extractions being independent on salt concentration (up to 1 M), temperature (up to 60 degrees C) and pH (below 4). Besides, the coacervate prevents the CPAHs from adsorption onto the surface of containers during sample storage. No clean-up steps are necessary and the method is matrix-independent. The quantification and detection limits of the method ranged between 0.4 and 3.5 ng L(-1) and 0.1 and 1 ng L(-1), respectively, for the seven priority CPAHs. The method has been successfully applied to the determination of these pollutants in raw and treated sewage from three mechanical-biological treatment plants, two rivers and a reservoir with frequent motorized recreational craft activities, all of them located in the South of Spain. Recoveries for spiked samples in the range 2-30 ng L(-1) were between 88 and 95% with relative standard deviations from 1 to 7%. CPAHs were present in wastewater influents at concentrations in the range 3.9-37 ng L(-1), while the treatment at the WWTPs studied reduced their concentration in their respective effluents in a percentage near 100%. Three CPAHs were present at quantifiable levels in Guadajoz river (1.8-6.6 ng L(-1)) and six in La Breña reservoir (1.39-4.8 ng L(-1)).

Supramolecular solid-phase extraction of ibuprofen and naproxen from sewage based on the formation of mixed supramolecular aggregates prior to their liquid chromatographic/photometric determination.

Sorbents made up of sodium dodecyl sulphate (SDS) hemimicelles, formed onto gamma-alumina, were proposed for the quantitative and practically solvent-free solid-phase extraction (SPE) of ibuprofen and naproxen from sewage samples. The formation of drug-SDS mixed aggregates was proved by the pseudophase separation model and their composition as a function of the amount of drug was calculated. The overall hemimicellar SPE procedure consumed only 0.6 mL of methanol since non-organic solvent was required for cartridge conditioning and the drugs were completely eluted using 2 mL of a 0.3M NaOH:methanol (70:30, v/v) solution. Breakthrough volumes of around 0.75 L and above 1L were obtained for naproxen and ibuprofen, respectively. No clean-up steps were necessary for the determination of these drugs in sewage because the direct analysis of the eluates by liquid chromatography/UV was matrix effect-free. The identification of the analytes was based on retention times and UV spectra and it was confirmed by on-line fluorescence detection. The detection limits for naproxen and ibuprofen were 0.8 and 9 ng L(-1) in wastewater influents and 0.5 and 7 ng L(-1) in effluents, respectively. These limits were similar to or lower than those achieved by methods based on conventional sorbents (e.g. C(18)-silica or polymeric resins), which invariably require the evaporation of the eluates. The accuracy and precision of the proposed method were assessed by analysing influent and effluent wastewater samples spiked with 2 and 0.4 microg L(-1) of each analyte, respectively. The recoveries obtained and the corresponding standard deviations were in the ranges 93-101% and 2-9%. The method was applied to the determination of the target drugs in wastewater from three sewage treatment plants (STPs) in the south of Spain. The concentration of ibuprofen and naproxen ranged between 2.0 and 7.4 microg L(-1) and 0.9 and 3.3 microg L(-1) in influents and 0.4 and 1.4 microg L(-1) and 0.2 and 0.8 microg L(-1) in effluents, respectively.

Vesicular coacervative extraction of bisphenols and their diglycidyl ethers from sewage and river water.

Coacervates made up of vesicles of decanoic acid, induced by tetrabutylammonium, are proposed for the extraction of bisphenols A and F (BPA, BPF) and their corresponding diglycidyl ethers (BADGE and BFDGE) from sewage and river water. The driving forces for the extraction were hydrophobic, hydrogen bonding and pi-cation. Actual concentration factors depended mainly on the amount of decanoic acid and tetrabutylammonium making up the coacervate. Under optimal experimental conditions, they were 569, 561, 500 and 477 for BPA, BPF, BADGE and BFGDE, respectively. Extractions were independent of the presence of salts up to 1M and the temperature up to 60 degrees C. Equilibrium conditions were reached in 5 min. The combination of vesicular coacervation with liquid chromatography and fluorescence detection at lambda(exc) 278 nm and lambda(em) 306 nm permitted the quantification of the target pollutants with detection limits of 9-10 ng/L. The method was applied to their determination in raw and treated sewage and river samples. No clean-up steps were necessary. Apparent recoveries of bisphenols and their diglycidyl ethers in the environmental water samples ranged from 95 to 102%. The concentrations of BPA and BPF in samples were between 0.1 and 1.7 microg/L. BADGE was found mainly in wastewater influents, at concentrations ranging between 0.49 and 1.15 microg/L, whereas BFDGE was only found in one of the 11 samples analysed.

Surfactant to dye binding degree based approach for the selective determination of L-glutamate in foodstuffs.

A selective method for the determination of L-glutamate in foodstuffs has been developed. It was based on the competition established between the analyte and the dye Coomassie brilliant blue G (CBBG) to interact with the surfactant didodecyldimethylammonium bromide (DDABr). The measurement parameter was the amount of DDABr required to reach a given dye-to-surfactant binding degree. It was obtained by photometric titration on the basis of the changes observed in the spectral characteristics of the dye when CBBG-DDABr aggregates were formed. The calibration graph obtained was linear in the L-glutamate concentration interval 0.2-5 mM (detection limit 0.05 mM). The high selectivity of the proposed method (other amino acids and food additives did not interfere at the concentrations present in foodstuffs) permitted the direct analysis of food samples after dissolution of the analyte in hot water. The accuracy of the surfactant to the dye binding degree method was demonstrated by determining L-glutamate in different kinds of foodstuffs (liquid and dried soups, seasonings, pasta sauces and dried mushroom creams) and comparing the results obtained with those provided by the commercial Boehringer Mannheim essay.

Determination of alkylphenols and alkylphenol carboxylates in wastewater and river samples by hemimicelle-based extraction and liquid chromatography-ion trap mass spectrometry.

Sodium dodecyl sulfate (SDS)-coated alumina and cetylpyridinium chloride (CPC)-coated silica were investigated as new sorbents for the concentration of alkylphenol polyethoxylate (APE) biodegradation products from wastewater and river water samples. Octylphenol (OP), nonylphenol (NP), octylphenol carboxylic acid (OPC) and nonylphenol carboxylic acid (NPC) were quantitatively retained on both supramolecular sorbents on the basis of the formation of mixed hemimicelles and admicelles. SDS hemimicelles-based SPE was proposed for the extraction/concentration of the target compounds prior to their separation and quantitation by liquid chromatography/electrospray ionization in negative mode, ion trap mass spectrometry. No clean-up steps or evaporation of the eluent were required. The recovery of APE metabolites from sewage and river water ranged between 87 and 100%. Concentration factors of about 500, using sample volumes of 1 l, were achieved. Detection limits were between 75 and 193 ng/l. The approach developed was applied to the determination of alklylphenols and alkylphenol carboxylic acids in raw and treated sewage and river samples. The concentrations of APE metabolites found ranged between 0.8 and 78 microg/l.

Determination of non-ionic polyethoxylated surfactants in wastewater and river water by mixed hemimicelle extraction and liquid chromatography-ion trap mass spectrometry.

The capability of hemimicelles-based solid phase extraction (SPE)/liquid chromatography/atmospheric pressure chemical ionisation in positive mode, ion trap mass spectrometry (LC/(APCl+-IT)-MS) for the concentration, separation and quantitation of non-ionic surfactants has been investigated. Concentration was based on the formation of mixed aggregates of analytes [alkylphenol ethoxylates (APE, octyl and nonyl) and alkyl ethoxylates (AE, C12-C16)] with the anionic surfactant sodium dodecyl sulphate (SDS) that is adsorbed on alumina. Parameters affecting SPE were investigated on the basis that hemimicelles are dynamic entities in equilibrium with the aqueous phase. The performance of ion trap mass spectrometry for MS and MS/MS quantitation of non-ionic homologues was assessed. Recoveries of analytes from wastewater influent and effluent and river water samples ranged between 91 and 98% and were found independent on the length of the alkyl chain under the optimised conditions. Anionic surfactants did not interfere to the levels found in environmental samples. The detection limits ranged between 14 and 111 ng/l for wastewater influent, 10 and 40 for wastewater effluent and 4 and 35 for river water, after concentration of 250, 500 and 750 ml of sample, respectively. The approach was applied to the determination of AE and APE in influent and effluent samples from four wastewater treatment plants and four river samples. The concentrations of individual non-ionic surfactants found ranged between 0.3 and 373 microg/l.

Determination of bisphenols in sewage based on supramolecular solid-phase extraction/liquid chromatography/fluorimetry.

Supramolecular sorbents (hemimicelles/admicelles) are proposed for the extraction/preconcentration of bisphenols from aqueous environmental samples prior to their liquid chromatography/fluorimetric determination. A comparative study on the use of cetyltrimethylammonium bromide (CTABr)-coated silica and sodium dodecyl sulphate (SDS)-coated gamma-alumina as sorbent materials, is presented. Bisphenol A (BPA) and bisphenol F (BPF) were quantitatively retained on CTABr admicelles. Addition of tetrabutylammonium chloride (TBAC) to water samples was required to completely retain bisphenols on SDS-gamma-alumina. Retention on both sorbents occurred through hydrophobic and pi-cation interactions between the quaternary ammonium head group of the cationic amphiphile (CTABr or TBAC) and the aromatic rings of the target analytes. TBAC-SDS-gamma-alumina was the sorbent selected for the SPE of bisphenols on the basis of the lower elution volume required (1 ml of methanol) and the greater breakthrough volume allowed (400 ml), which permitted to reach practical detection limits of 10 and 15 ng/l for BPF and BPA, respectively. The proposed method was used to quantify bisphenol A and bisphenol B in wastewater samples from four sewage treatment plants. Recoveries obtained ranged between about 99 and 105% for raw wastewater and between 96 and 106% for treated wastewater.

Stability of benzalkonium surfactants on hemimicelle-based solid-phase extraction cartridges.

The capability of hemimicelle-based solid-phase extraction cartridges for the preservation of organic compounds after their concentration from water samples was investigated for the first time. The approach is illustrated by studying the stability of benzalkonium homologue (C12, C14 and C16) surfactants (BAS) on monolayers of dodecyl sulphate (SDS) hemimicelles formed on alumina. The stability study included storage of cartridges at room temperature, at 4 and -20 degrees C, during a period of up to 3 months. The influence of water matrix components was also investigated from parallel experiments using spiked distilled, river and wastewater samples. Complete recovery of BAS was obtained for all storage conditions tested. Recoveries were independent on the alkyl chain length of BAS homologues and water matrix. The SPE of BAS on the SDS hemimicelles had a strong stabilizing effect for the target compounds and their analysis can be accomplished after at least 3 months without the necessity of special storage conditions for cartridges. Because of the lack of data, an additional stability study was carried out for BAS in an aqueous matrix using traditional preservation methods such as acidification (pH 2)/refrigeration, addition of formaldehyde (5%)/refrigeration, and freezing (-20 degrees C). Only combination of chemical addition (e.g. nitric acid or formaldehyde)/refrigeration was found effective to preserve BAS in the short term (e.g. for a week), then losses up to 40% were observed for these target compounds after a month.

Mixed aggregate-based acid-induced cloud-point extraction and ion-trap liquid chromatography-mass spectrometry for the determination of cationic surfactants in sewage sludge.

Alkyl ammonium surfactants were extracted and concentrated from sludge samples using the acid-induced cloud-point extraction (ACPE) technique. Reversed-phase liquid chromatography-electrospray ionization in positive ion mode ion-trap mass spectrometry was then used for the separation, quantitation and identification of single homologues of the cationic surfactants. Variables affecting the ACPE efficiency were optimized using a spiked activated sludge. Total method recoveries ranged from 91 to nearly 100%. Detection limits for cationics in the sludge were between 40 and 75 ng/g. The analysis of cationic surfactants in activated and dehydrated sludge collected from two different sewage treatment plants revealed the presence of dialkyldimethyl, alkylbenzyldimethyl and alkyltrimethyl ammonium in the concentration range from 0.1 to 34 mg/kg. Alkylpyridinium surfactants were not detected. The persistence of alkyl ammonium surfactants in sewage sludge after treatments applied at municipal sewage plants was confirmed.

Potential of coacervation processes for the extraction of amphiphiles (linear alkyl benzenesulphonates) from sewage sludge samples prior to liquid chromatography.

A new approach was developed for the monitoring of linear alkyl (C10-C13) benzenesulphonates (LASs) in sewage sludge. It was based on their extraction with the anionic surfactant sodium dodecanesulphonate (SDoS) that undergoes coacervation under acid conditions. The target compounds formed mixed aggregates with SDoS by ideal hydrophobic interactions which made possible the breakdown of LAS-sludge interactions and provided high extraction yields. Variables affecting extraction were optimised using a fortified dehydrated sludge. Recoveries for LASs were found independent on the length of alkyl chain. Liquid chromatography-fluorimetry was used for separation and detection of LAS homologues. Detection limit for LAS in the sludge was 5 mg/kg. Concentration levels of total LASs in activated and dehydrated sludge collected from two different sewage treatment plants were in the range 0.26-0.56 g/kg with LAS homologues ranging from 29 to 223 mg/kg. The method did not require clean-up or preconcentration steps.

Determination of non-ionic polyethoxylated surfactants in sewage sludge by coacervative extraction and ion trap liquid chromatography-mass spectrometry.

Alkylphenol polyethoxylates (APE, nonyl and octyl) and alcohol ethoxylates (AE, C12-C16) were analysed in sewage sludge by extraction with sodium dodecane sulphonate (SDoS), that undergoes coacervation under acid conditions, followed by quantitation with liquid chromatography/atmospheric pressure chemical ionisation ion/trap mass spectrometry, in positive ion mode. Coacervative extraction was optimised using an aged, fortified dehydrated sludge. Recoveries ranged from 78 to nearly 100% irrespective of the sludge matrix analysed. The method provided good agreement between the ethoxamer distribution of surfactants after extraction from sludge and that in the original surfactant. Detection limits for polyethoxylated surfactants in the sludge were 0.09-0.38 mg/kg. The procedure was used to assess the concentrations of APE and AE in activated and dehydrated sludge from two sewage treatment plants. Polyethoxylates were found in all samples in the concentration ranges 11-151, 100-138 and 23-141 mg/kg for octylphenol, nonylphenol and individual AE homologues, respectively. The method did not require clean-up or preconcentration steps.

Differentiation and quantification of linear alkyl benzenesulfonate isomers by liquid chromatography-ion-trap mass spectrometry.

Discrimination and quantitation of the 20 positional isomers of C10-C13 linear alkyl benzenesulfonates (LASs), based on the use of reversed-phase liquid chromatography-electrospray ionisation in negative ion mode ion-trap mass spectrometry, was undertaken. Discrimination was achieved by LAS MS-MS analysis into the ion trap, by monitoring specific fragment ions resulting from the benzylic cleavage of the carbon alkyl chain on both side of the LAS phenyl group. Parameters affecting the electrospray ionisation source and the ion-trap operation were optimised. Calibration curves for the different isomers were established and this permitted their quantitation by mass spectrometry for the first time. MS-MS responses were dependent on both the position of the phenyl group on the alkyl chain and the length of this alkyl chain, these responses being higher for the external isomers and the longer alkyl chain homologues. The precision, expressed as relative standard deviation ranged between 9 and 13%. Detection limits for LAS isomers were between 0.03 and 0.07 mg/l and therefore the method is sensitive enough to be applied to environmental samples.

Acid-induced cloud point extraction and preconcentration of polycyclic aromatic hydrocarbons from environmental solid samples.

The effectiveness of the acid-induced phase separation of anionic surfactants (acid-induced cloud point extraction, ACPE) to extract polycyclic aromatic hydrocarbons (PAHs) from different environmental samples (soils, sediments and sludges), prior to chromatographic analysis, was evaluated. Variables affecting the ACPE efficiency were optimised using a natural matrix (a harbour sediment, CRM 535). Temperature, surfactant concentration and stirring were of primary importance to maximise recovery, whereas temperature and surfactant/hydrochloric acid concentration influenced the volume of the surfactant-rich phase and therefore the preconcentration factor achieved. The optimal conditions (2% sodium dodecanesulphonate (SDoS), 4.2 M HCl, 60 degrees C, 1 h) were applied to the extraction of PAHs from various matrices and the ACPE recoveries compared to certified results from Soxhlet extractions. Recoveries obtained for four to five aromatic ring PAHs ranged from 71 to 98%. Uncertainties obtained using ACPE were similar to or lower than those provided for the certified values. The volume of the extracts ranged from 1 to 2 ml. The method did not require additional clean-up or preconcentration steps.

H2O2/TiO2 photocatalytic oxidation of metol. Identification of intermediates and reaction pathways.

The applicability of H2O2 to increase the efficiency of TiO2 photocatalytic degradations was investigated. The photographic developer metol [N-methyl-p-aminophenol] that does not adsorb on the surface of TiO2 particulates was used as a model for this purpose. It was proved that metol was mineralised under oxidation with H2O2/TiO2/UV through different thermal and photochemical reactions. Identification of intermediates by both HPLC-electron impact-MS and HPLC-electrospray ionisation-MS helped to elucidate the role of H2O2 and TiO2 in the degradation process and to establish degradation pathways. Intermediates yielded were partially oxygenated aromatic species and dimers, which were amenable to oxidation. The optimal degradation conditions found for mineralisation were 0.4 M H2O2, 5 mg/ml TiO2, pH 9 and irradiation centred at 360 nm (4.9 mW/cm2). The use of oxidants opens an interesting medium to the treatment of effluents containing a diversity of organics since they increase substantially the efficiency of TiO2 photocatalytic degradations.

Evaluation of the mixed aggregate method as an alternative to the bismuth active substances and cobalt thiocyanate active substances procedures for the determination of nonionic surfactants in raw and treated sewage.

The mixed aggregate (MA) method was evaluated for the routine determination of total ethoxylated nonionic surfactants in municipal raw and treated sewage. Nonionics in wastewater samples were enriched with a C8 solid-phase extraction cartridge, eluted with ethyl acetate-methanol, and separated from interferences with stacked strong anionic (quaternary ammonium form) and cationic (benzenesulfonic acid form) exchange columns. Sample extracts were evaporated to dryness and redissolved in distilled water. The total amount of ethoxylates, on a weight basis, was determined by measuring the critical micelle concentration of a mixed micelle made up of ethoxylates and the anionic surfactant sodium dodecyl sulfate, used as the reagent. The dye Coomassie Brilliant Blue G was used as a photometric probe. The minimum amount of ethoxylate required for a single determination was 1 microg. For raw sewage samples, mean recoveries and standard deviations were 98 +/- 6 and 98 +/- 4% at fortification levels of 0.3 and 0.6 microg/mL, respectively. For treated sewage samples, mean recoveries and standard deviations were 95 +/- 2 and 100 +/- 2% at fortification levels of 0.03 and 0.06 microg/mL, respectively. The MA method and the classical bismuth active substances and cobalt thiocyanate active substances procedures were compared. The former offers some significant advantages over the classical procedures in terms of sensitivity, selectivity, precision, simplicity, and rapidity; the type of response is independent of both the molecular weight and the chain length of the surfactant.

Supramolecular solvent-based microextraction of ochratoxin A in raw wheat prior to liquid chromatography-fluorescence determination.

A supramolecular solvent made up of reverse micelles of decanoic acid, dispersed in a continuous phase of THF:water, was proposed for the simple, fast and efficient microextraction of OTA in wheat prior to liquid chromatography-fluorescence determination. The method involved the stirring of 300 mg-wheat subsamples (particle size 50microm) and 350microL of supramolecular solvent for 15min, subsequent centrifugation for 15min and the direct quantitation of OTA in the extract, previous 5.7-fold dilution with ethanol/water/acetic acid (49.5/49.5/1), against solvent-based calibration curves. No clean-up of the extracts or solvent evaporation was needed. Interactions between the supramolecular solvent and major matrix components in the wheat (i.e. carbohydrates, lipids and proteins) were investigated. The reverse micelles in the extractant induced gluten flocculation but only in the coacervation region of lower analytical interest (i.e. at percentages of THF above 11%). The quantitation of OTA was interference-free. Representativity of the 300 mg-wheat subsamples was proved by analysing a reference material. OTA recoveries in wheat ranged between 84% and 95% and the precision of the method, expressed as relative standard deviation, was 2%. The quantitation limit of the method was 1.5microgkg(-1) and was below the threshold limit established for OTA in raw cereals by EU directives (5.0microgkg(-1)). The method developed was validated by using a certified reference material and it was successfully applied to the determination of OTA in different wheat varieties from crops harvested in the South of Spain. OTA was not detected in any of the analysed samples. This method allows quick and simple microextraction of OTA with minimal solvent consumption, while delivering accurate and precise data.