On-line trace enrichment of phenolic compounds from water using a pyrrole-based polymer as the solid-phase extraction sorbent coupled with high-performance liquid chromatography

A pyrrole-based conductive polymer was prepared and applied as new sorbent for on-line solid-phase extraction (SPE) of phenol and chlorophenols from water samples. Polypyrrole (PPy) was synthesized by chemical oxidation of the monomer in non-aqueous solution. The efficiency of this polymer for extraction of phenol and chlorophenols was evaluated using 35 mg of PPy as the sorbent in an on-line SPE system coupled to reversed-phase liquid chromatography with UV detection. The mobile phase were mixture of phosphate buffer-acetonitrile and compounds were eluted by the mobile phase using a six-port switching valve. High volumes of water, up to 160 ml, could be preconcentrated without the loss of phenols, except for the more polar ones. The R.S.D. for a river water sample spiked with phenol and chlorophenols at sub-ppb level was lower than 7% (n=5) and detection limits of 15-100 and 35-150 ng l⁻¹ for tap and river water were obtained, respectively.     

Analysis of aflatoxins in nonalcoholic beer using liquid–liquid extraction and ultraperformance LC‐MS/MS

Aflatoxins AFB1, AFB2, AFG1, and AFG2 are toxic secondary metabolites produced by Aspergillus flavus and Aspergillus parasiticus and posses a potential threat to food safety. In the present work, liquid–liquid extraction and ultraperformance LC‐MS/MS method has been applied for the determination of four naturally occurring aflatoxins AFB1, AFB2, AFG1, and AFG2 in nonalcoholic beer. Aflatoxins extraction from nonalcoholic beer was carried out using liquid–liquid extraction procedure. The effects of solvent‐types were studied to obtain maximum recovery of the target analytes with minimum contamination. Among different solvents, the aflatoxins extraction was best achieved using ethyl acetate. The obtained recoveries were ranged from 85 to 96% with good quality parameters: LOD values between 0.001 and 0.003 ng/mL, linearity of the calibration curve (r² > 0.999), and repeatability (run‐to‐run) and reproducibility (day‐to‐day) precisions with RSDs lower than 5% (n = 5) achieved at 0.50 ng/mL concentration. The optimized liquid–liquid extraction in combination with ultraperformance LC‐MS/MS was applied successfully to the analysis of AFB1, AFB2, AFG1, and AFG2 aflatoxins in 11 nonalcoholic beers and were detected up to 15.31 ng/L in some of the samples.     

The investigation of electrospun polymer nanofibers as a solid-phase extraction sorbent for the determination of trazodone in human plasma

A novel micro-extraction procedure was developed through the use of an electrospun polymer nanofiber as a solid-phase extraction (SPE) sorbent to directly extract trazodone from human plasma. The target compound was then monitored by a high performance liquid chromatography with ultraviolet detector (HPLC-UV) system. Parameters of influencing the extraction efficiency, such as fiber diameter, fiber packing amount, eluted solvent, pH and ionic strength were investigated. Under the optimized conditions, a linear response for trazodone over the range of 20-2000 ng mL⁻¹ was achieved with a γ² value of 0.9996. The precision of the method was examined with relative standard deviations of 5.7, 2.7, 2.2% corresponding to 50, 200, and 500 ng mL⁻¹, respectively, of trazodone spiked into 0.1 mL of plasma samples. The extraction recoveries of 58.3-75.2% and the relative recoveries of 94.6-105.5% were obtained. The limit of detection (LOD) was determined to be 8 ng mL⁻¹. A 15 min of HPLC gradient was successfully applied to determine trazodone from human plasma. Due to its simplicity, selectivity and sensitivity, the method may be applied to pharmacokinetic and pharmacodynamic studies of drugs.     

Determination of nicardipine and amlodipine in human plasma using on-line solid-phase extraction with a monolithic weak cation-exchange column

An on-line solid-phase extraction (SPE)-HPLC method was developed for simultaneous screening of nicardipine and amlodipine in human plasma. A short monolithic poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) [p(GMA-EDMA)]-based weak cation-exchange (WCX) column was prepared and employed as the selective extraction sorbent, which exhibited good permeability and biocompatibility. During the on-line SPE protocol, high-abundance proteins (human serum albumin, immunoglobulin G, immunoglobulin A and transferrin) and most matrixes in plasma were fast removed while nicardipine and amlodipine were effectively trapped on this monolithic column. Furthermore, the monolithic WCX sorbent could be continuously reused more than 300 times without obvious changes in analytes extraction and proteins cleanup. The proposed method was linear over a range of 0.5-50.0 ng mL⁻¹ for both analytes with a linear regression coefficient greater than 0.998, and the limit of detection (LOD) for each analyte was 0.2 ng mL⁻¹. Validation assays also demonstrated acceptable precision and adequate recovery for simultaneous quantitative screening of nicardipine and amlodipine in human plasma. Real plasma samples from hypertensive patients receiving a dosing of 5 mg antagonists were examined by using the proposed method. Results indicated that the on-line SPE-HPLC method could be applied for simultaneously monitoring of nicardipine and amlodipine in clinical plasma samples.     

Synthetic approaches to parabens molecularly imprinted polymers and their applications to the solid-phase extraction of river water samples

In this paper we describe the synthesis, characterisation and use of two distinct molecularly imprinted polymers (MIPs) prepared using esters of p-hydroxybenzoic acid (parabens) as templates: one MIP was synthesised by precipitation polymerisation using a semi-covalent molecularly imprinting strategy with methyl paraben as the template/target (MIP 1); the second MIP was prepared in monolithic form through a conventional non-covalent molecular imprinting strategy, with butyl paraben as the template (MIP 2). MIP 1 recognized methyl paraben, showed cross-selectivity for other parabens analytes used in the study and higher affinity towards these compounds than did a non-imprinted control polymer. Similarly, MIP 2 demonstrated higher affinity towards paraben analytes than a non-imprinted control polymer.For the analysis of environmental water samples, a solid-phase extraction (SPE) protocol was developed using MIP 2 as sorbent, and results were compared to a SPE using a commercial sorbent (Oasis HLB). With MIP 2 as sorbent and butyl paraben as target, when percolating 500 mL of river water spiked at 1 μg L⁻¹ through the SPE cartridge, and using 1 mL of isopropanol as cleaning solvent, a higher recovery of butyl 4-hydroxybenzoate (butyl paraben) and a cleaner chromatogram where achievable when using the MIP compared to the commercial sorbent.     

Synthesis and application of hypercrosslinked polymers with weak cation-exchange character for the selective extraction of basic pharmaceuticals from complex environmental water samples

The synthesis of high specific surface area sorbents (HXLPP-WCX) in the form of hypercrosslinked polymer microspheres with narrow particle size distributions, average particle diameters around 6 μm, and weak cation-exchange (WCX) character, is described. The WCX character arises from carboxylic acid moieties in the polymers, derived from the comonomer methacrylic acid. A novel HXLPP-WCX sorbent with an attractive set of chemical and physical properties was then used in an off-line solid-phase extraction (SPE) protocol for the selective extraction of a group of basic compounds from complex environmental samples, a priority being the clean separation of the basic compounds of interest from acidic compounds and interferences. The separation power of the new sorbent for basic pharmaceuticals was compared to two commercially available, mixed-mode sorbents, namely Oasis WCX and Strata-X-CW. Under identical experimental conditions, HXLPP-WCX was found to deliver both higher capacity and better selectivity in SPE than either of the two commercially available materials. In an optimised SPE protocol, the HXLPP-WCX sorbent gave rise to quantitative and selective extractions of low μg l⁻¹ levels of basic pharmaceuticals present in 500 ml of river water and 250 ml of effluent waste water.     

Measurement of trace levels of antibiotics in river water using on-line enrichment and triple-quadrupole LC-MS/MS

This study presents the development of an automated on-line solid phase extraction (SPE)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of 23 antibiotics in environmental water samples. After optimisation of LC-MS/MS conditions, SPE parameters such as sorbent type, sample pH or sample volume were optimised. Antibiotic recoveries ranged from 64% to 98% and compared favourably with those achieved using off-line SPE. Limits of detection were in the range 0.5-13.7 ng L⁻¹.This on-line SPE-LC-MS/MS procedure was applied to the analysis of water samples taken in three rivers within the Seine River basin, near Paris (France). The obtained results revealed the occurrence of 12 antibiotics, including tylosin, erythromycin, tetracycline, amoxicillin, trimethoprim, sulfamethoxazole, oxolinic acid, flumequine, norfloxacin, ciprofloxacin, ofloxacin, and vancomycin (2-1435 ng L⁻¹).     

Improving the sensitivity of the determination of ceftiofur by capillary electrophoresis in environmental water samples: in-line solid phase extraction and sample stacking techniques

This paper describes two different approaches for increasing the sensitivity for the analysis of ceftiofur by capillary electrophoresis (CE). Two different techniques based on the introduction of an enlarged volume of sample, namely large volume sample stacking (LVSS) and in-line solid phase extraction (SPE) were studied and compared. LVSS allowed the on-column electrophoretic preconcentration of ceftiofur without modification of the separation capillary. In-line SPE-CE was developed by using a home-made microcartridge that was filled with a reversed-phase sorbent (C₁₈). The microcartridge was coupled in-line near the inlet of the separation capillary. LVSS and in-line SPE-CE allowed automated operation and improved sensitivity for the analysis of ceftiofur with respect to conventional CE. When environmental water samples were analyzed, an additional pretreatment step based on off-line SPE was necessary in both cases to further decrease the detection limits. In terms of sensitivity for the determination of ceftiofur in river water samples, the combination of off-line SPE with in-line SPE-CE was found the most sensitive with a detection limit of 10 ng L⁻¹, whereas the method based on the use of off-line SPE with LVSS presented a detection limit of 100 ng L⁻¹.     

On-line coupling of dynamic microwave-assisted extraction to solid-phase extraction for the determination of sulfonamide antibiotics in soil

A rapid technique based on dynamic microwave-assisted extraction (DMAE) coupled on-line with solid-phase extraction (SPE) was developed for the determination of sulfonamides (SAs) including sulfadiazine, sulfameter, sulfamonomethoxine and sulfaquinoxaline in soil. The SAs were first extracted with acetonitrile under the action of microwave energy, and then directly introduced into the SPE column which was packed with neutral alumina for preconcentration of analytes and clean-up of sample matrix. Subsequently, the SAs trapped on the alumina were eluted with 0.3% acetic acid aqueous solution and determined by liquid chromatography-tandem mass spectrometry. The DMAE parameters were optimized by the Box-Behnken design. Maximum extraction efficiency was achieved using 320 W of microwave power; 12 mL of extraction solvent and 0.8 mL min⁻¹ of extraction solvent flow rate. The limits of detection and quantification obtained are in the range of 1.4-4.8 ng g⁻¹ and 4.6-16.0 ng g⁻¹ for the SAs, respectively. The mean values of relative standard deviation of intra- and inter-day ranging from 2.7% to 5.3% and from 5.6% to 6.7% are obtained, respectively. The recoveries of SAs obtained by analyzing four spiked soil samples at three fortified levels (20 ng g⁻¹, 100 ng g⁻¹ and 500 ng g⁻¹) were from 82.6 ± 6.0% to 93.7 ± 5.5%. The effect of standing time of spiked soil sample on the SAs recoveries was examined. The recoveries of SAs decreased from (86.3-101.9)% to (37.6-47.5)% when the standing time changed from one day to four weeks.     

Optimization of Matrix Solid-Phase Dispersion method for simultaneous extraction of aflatoxins and OTA in cereals and its application to commercial samples

A method based on Matrix Solid-Phase Dispersion (MSPD) has been developed for the determination of 5 mycotoxins (ochratoxin A and aflatoxins B and G) in different cereals. Several dispersants, eluents and ratios were tested during the optimization of the process in order to obtain the best results. Finally, samples were blended with C₁₈ and the mycotoxins were extracted with acetonitrile. Regarding to matrix effects, the results clearly demonstrated the necessity to use a matrix-matched calibration to validate the method. Analyses were performed by liquid chromatography-triple quadrupole-tandem mass spectrometry (LC-QqQ-MS/MS). The recoveries of the extraction process ranged from 64% to 91% with relative standard deviation lower than 19% in all cases, when samples were fortified at two different concentrations levels. Limits of detection ranged from 0.3 ng g⁻¹ for aflatoxins to 0.8 ng g⁻¹ for OTA and the limits of quantification ranged from 1 ng g⁻¹ for aflatoxins to 2 ng g⁻¹ for OTA, which were below the limits of mycotoxins set by European Union in the matrices evaluated. Application of the method to the analysis of several samples purchased in local supermarkets revealed aflatoxins and OTA levels.     

Sensitive determination of four camptothecins by solid-phase microextraction-HPLC based on a boronic acid contained polymer monolithic layer

Camptothecin (CPT) and its derivative have been revealed to possess special anti-cancer activity, extraction methods are necessary for trace determination of CPTs in complex samples. In this work, we prepared a high efficient boronic acid-based polymer monolithic layer for microextraction of CPTs. A disposable membrane filter-based extraction device was developed, and boronic acid groups were co-polymerized into a polyporous polymer skeleton and served as the monolithic sorbent. The prepared poly(4-VB-MA-TRIM) showed good stability and great extraction efficiency toward four CPTs. After optimization of extraction conditions, poly(4-VB-MA-TRIM)-based solid-phase microextraction was coupled HPLC for determination of CPTs in biological samples. The method exhibited low limits of detection of 0.05–0.2 ng mL⁻¹, which is significantly more sensitive than reported HPLC methods. The method also showed wide linear range (0.1–100 and 0.5–200 ng mL⁻¹), good linearity (R² ≥ 0.9981) and good reproducibility (RSD ≤3.76%). The method has been applied in plasma samples, with good selectivity and good recoveries ranging from 85.1 to 104.7%.     

Determination of aflatoxins in cereal flours by solid-phase microextraction coupled with liquid chromatography and post-column photochemical derivatization-fluorescence detection

A new method for the determination of aflatoxins B₁, B₂, G₁, and G₂ (AFB₁, AFB₂, AFG₁, AFG₂) in cereal flours based on solid-phase microextraction (SPME) coupled with high performance liquid chromatography with post-column photochemical derivatization and fluorescence detection (SPME–HPLC–PD–FD) has been developed. Aflatoxins were extracted from cereal flour samples by a methanol:phosphate buffer (pH 5.8, I = 0.1) (80:20, v/v) solution, followed by a SPME step. Different SPME and HPLC–PD–FD parameters (fiber polarity, temperature, pH, ionic strength, adsorption and desorption time, mobile phase) have been investigated and optimized. This method, which was assessed for the analysis of different cereal flours, showed interesting results in terms of LOD (from 0.035 to 0.2 ng g⁻¹), LOQ (from 0.1 to 0.63 ng g⁻¹, respectively), within and inter-day repeatability (2.27% and 5.38%, respectively) linear ranges (up to 20 ng g⁻¹ for AFB₁ and AFG₁ and 6 ng g⁻¹ for AFB₂ and AFG₂), and total raw extraction efficiency (in the range 55–59% at concentrations in the range 0.3–1 ng g⁻¹ and 49–52% at concentrations in the range 1–10 ng g⁻¹). The results were also compared with the purification step carried out by conventional immunoaffinity columns.     

Selective solid-phase extraction of nickel(II) using a surface-imprinted silica gel sorbent

A new Ni(II)-imprinted amino-functionalized silica gel sorbent with excellent selectivity for nickel(II) was prepared by an easy one-step reaction by combining a surface imprinting technique for selective solid-phase extraction (SPE) of trace Ni(II) in water samples prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Compared with non-imprinted polymer particles, the ion-imprinted polymers (IIPs) had higher selectivity and adsorption capacity for Ni(II). The maximum static adsorption capacity of the ion-imprinted and non-imprinted sorbent for Ni(II) was 12.61 and 4.25 mg g⁻¹, respectively. The relatively selective factor (α_r) values of Ni(II)/Cu(II), Ni(II)/Co(II), Ni(II)/Zn(II) and Ni(II)/Pd(II) were 45.99, 32.83, 43.79 and 28.36, which were greater than 1. The distribution ratio (D) values of Ni(II)-imprinted polymers for Ni(II) were greatly larger than that for Cu(II), Co(II), Zn(II) and Pd(II). The detection limit (3σ) was 0.16 ng mL⁻¹. The relative standard deviation of the method was 1.48% for eight replicate determinations. The method was validated by analyzing two certified reference materials (GBW 08618 and GBW 08402), the results obtained is in good agreement with standard values. The developed method was also successfully applied to the determination of trace nickel in plants and water samples with satisfactory results.     

Determination of fluoroquinolone antibiotics in environmental water samples based on magnetic molecularly imprinted polymer extraction followed by liquid chromatography-tandem mass spectrometry

A simple method based on magnetic separation for selective extraction of fluoroquinolones (FQs) from environmental water samples has been developed using magnetic molecularly imprinted polymer (MMIP) as sorbent. The MMIP has been prepared using ciprofloxacin as template molecule, methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linking agent and Fe₃O₄ magnetite as magnetic component. The polymer has been characterized by scanning electron microscopy, Fourier-transform infrared spectrometry and vibrating sample magnetometry. Various parameters affecting the extraction efficiency were evaluated in order to achieve optimal concentration and reduce non-specific interactions. The analytes desorbed from the polymers were determined by liquid chromatography-tandem mass spectrometry. The matrix effect was evaluated by using different washing solvents for removing interfering compounds from the MMIPs after sample loading. Under the optimal conditions, the linearity of the method obtained is in the range of 20-2000 ng L⁻¹. The detection limits of FQs are in the range of 3.2-6.2 ng L⁻¹. The relative standard deviations of intra- and inter-day tests ranging from 2.5 to 7.2% and from 3.6 to 9.1% are obtained. In all three spiked levels (20, 100 and 200 ng L⁻¹), the recoveries of FQs are in the range of 76.3-94.2%. The proposed method was successfully applied to determine FQs including ciprofloxacin, enrofloxacin, lomefloxacin, levofloxacin, fleroxacin and sparfloxacin in different water samples, such as lake water, river water, primary and final sewage effluent. Ciprofloxacin and fleroxacin were found in primary and final sewage effluent samples with the contents in the range of 26-87 ng L⁻¹.     

Hydrophilic hypercrosslinked polymeric sorbents for the solid-phase extraction of polar contaminants from water

Three new hypercrosslinked polymers with hydrophilic character arising from hydroxyl moieties in their skeletons have been prepared in microsphere format and applied to the off-line solid-phase extraction (SPE) of polar compounds from water samples. For sample volumes of 1000 ml, the recoveries of various polar pesticides, such as oxamyl, methomyl, selected phenolic compounds, as well as some pharmaceuticals, were close to 90%. The HXLPP-polar polymer with the best performance characteristics was applied to real samples. Its performance was also compared to commercially available sorbents, such as LiChrolut EN (hydrophobic, hypercrosslinked), Oasis HLB (hydrophilic, macroporous) and Isolute ENV+ (hydrophilic, hypercrosslinked); the new sorbent out-performed the commercially available sorbents. The polymer was applied successfully in off-line SPE of river water samples followed by liquid chromatography and ultraviolet detection, providing a good linear range and detection limits of 0.2 μg l⁻¹ for the majority of the compounds, with the exception of oxamyl, methomyl, guaiacol and salicylic acid where the detection limit was 0.5 μg l⁻¹.     

Preparation and evaluation of an immunoaffinity sorbent with Fab′ antibody fragments for the analysis of opioid peptides by on-line immunoaffinity solid-phase extraction capillary electrophoresis–mass spectrometry

An immunoaffinity (IA) sorbent with antibody fragments was prepared for the analysis of opioid peptides by on-line immunoaffinity solid-phase extraction capillary electrophoresis–mass spectrometry (IA-SPE-CE–MS). The antibody fragmentation was evaluated by MALDI-TOF-MS. Fab′ fragments obtained from a polyclonal IgG antibody against Endomorphins 1 and 2 (End1 and End2) were covalently attached to succinimidyl silica particles to prepare the IA sorbent. An IA-SPE-CE–MS methodology was established analyzing standard solutions of End1 and End2 and acceptable repeatability, linearity ranges and LODs (0.5 and 5 ng mL⁻¹, respectively) were obtained. The LOD of End1 was slightly better than that previously obtained using an IA sorbent with intact antibodies (1 ng mL⁻¹). In human plasma samples, End1 and End2 could be detected at 1 and 50 ng mL⁻¹, respectively, which meant an improvement of 100 and 2-fold with regard to the LODs using an IA sorbent with intact antibodies (100 ng mL⁻¹).     

At-line microextraction by packed sorbent-gas chromatography–mass spectrometry for the determination of UV filter and polycyclic musk compounds in water samples

An at-line analysis protocol is presented that allows the determination of four UV filters, two polycyclic musk compounds and caffeine in water at concentration level of ng L⁻¹. The fully automated method includes analytes enrichment by Microextraction by packed sorbent (MEPS) coupled directly to large volume injection-gas chromatography–mass spectrometry. Two common SPE phases, C8 and C18, were examined for their suitability to extract the target substances by MEPS. The analytes were extracted from small sample volumes of 800 μL with recoveries ranging from 46 to 114% for the C8-sorbent and 65–109% for the C18-sorbent. Limits of detection between 34 and 96 ng L⁻¹ enable the determination of the analytes at common environmental concentration levels. Both sorbents showed linear calibration curves for most of the analytes up to a concentration level of 20 ng mL⁻¹. Carryover was minimized by washing the sorbents 10 times with 100 μL methanol. After this thorough cleaning, the MEPS are re-used and up to 70 analyses can be performed with the same sorbent. The fully automated microextraction GC–MS protocol was evaluated for the influence of matrix substances typical for wastewater. Dilution of samples prior to MEPS is recommended when the polar caffeine is present at high concentration. Real water samples were analyzed by the MEPS-GC–MS method and compared to standard SPE.     

Selective pretreatment and determination of phenazopyridine using an imprinted polymer-electrospray ionization ion mobility spectrometry system

In this research, selective separation and determination of phenazopyridine (PAP) is demonstrated using molecular imprinted polymer (MIP) coupled with electrospray ionization ion mobility spectrometry (ESI-IMS). In the non-covalent approach, selective MIP produced using PAP and methacrylic acid (MAA) as a template molecule and monomer, respectively. The created polymer is utilized as a media for solid-phase extraction (SPE), revealing selective binding properties for the analyte from pharmaceutical and serum samples. A coupled MIP-IMS makes it possible to quantitize PAP in the range of 1-100 ng mL⁻¹ and with a 0.2 ng mL⁻¹ detection limit. Furthermore, the MIP selectivity is evaluated by application of some substances with analogous and different molecular structures to that of PAP. This method is successfully applied for the determination of PAP in pharmaceutical and serum samples.     

Determination of 16 polycyclic aromatic hydrocarbons in environmental water samples by solid-phase extraction using multi-walled carbon nanotubes as adsorbent coupled with gas chromatography–mass spectrometry

A solid-phase extraction (SPE) using multi-walled carbon nanotubes (MWCNTs) as adsorbent coupled with gas chromatography–mass spectrometry (GC–MS) method was developed for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. Several condition parameters, such as extraction adsorbents, elution solvents and volumes, and sample loading flow rate and volume were optimized to obtain high SPE recoveries and extraction efficiency. 150 mg MWCNTs as sorbent presented high extraction efficiency of 16 PAHs due to the large specific surface area and high adsorption capacity of MWCNTs compared with the commercial C18 column (250 mg/2 mL). The calibration curves of 16 PAHs extracted were linear in the range of 20–5000 ng L⁻¹, with the correlation coefficients (r²) between 0.9848 and 0.9991. The method attained good precisions (relative standard deviation, RSD) from 1.2% to 12.1% for standard PAHs aqueous solutions; method recoveries ranged in 76.0–125.5%, 74.5–127.0%, and 70.0–122.0% for real spiked samples from river water, tap water and seawater, respectively. Limits of detection (LODs, S/N = 3) of the method were determined from 2.0 to 8.5 ng L⁻¹. The optimized method was successfully applied to the determination of 16 PAHs in real environmental water samples.     

Mixed-mode solid-phase extraction followed by acetylation and gas chromatography mass spectrometry for the reliable determination of trans-resveratrol in wine samples

This work presents an advantageous analytical procedure for the accurate determination of free trans-resveratrol in red and white wines. The proposed method involves solid-phase extraction (SPE), acetylation of the analyte in aqueous media and further determination by gas chromatography (GC) with mass spectrometry detection (MS). The use of a mixed-mode SPE sorbent provides an improvement in the selectivity of the extraction step; moreover, the presence of several intense ions in the electron impact mass spectra of its acetyl derivative guarantees the unambiguous identification of trans-resveratrol. Considering a sample intake of 10 mL, the method provides a limit of quantification (LOQ) of 0.8 ng mL⁻¹ and linear responses for concentrations up to 2.5 μg mL⁻¹, referred to wine samples. The average recovery, estimated with samples fortified at different concentrations in the above range, was 99.6% and the inter-day precision stayed below 8%. Trans-resveratrol levels in the analyzed wines varied from 3.4 to 1810 ng mL⁻¹. Cis-resveratrol was also found in all samples. In most cases, equal or higher responses were measured for this latter form than for the trans-isomer. The reduced form of resveratrol, dihydro-resveratrol, was systematically identified in red wines.