A nanocomposite adsorbent of metallic copper, polypyrrole, halloysite nanotubes and magnetite nanoparticles for the extraction and enrichment of sulfonamides in milk.

A composite adsorbent composed of metallic copper (Cu), polypyrrole (PPy), halloysite nanotubes (HNTs) and magnetite nanoparticles (Fe3O4) was developed to extract and enrich sulfonamides by dispersive magnetic solid phase extraction. The composite could adsorb sulfonamides via hydrogen bonding and hydrophobic, π-π and π-electron-metal interactions. The extraction conditions were optimized and the developed composite adsorbent was characterized and provided a large surface area that enhanced extraction efficiency for sulfonamides. Coupled with high performance liquid chromatography, the adsorbent was used to quantitatively determine sulfonamides found in milk samples. The response of the developed method exhibited linearity from 5.0 to 150.0 µg kg-1 for sulfathiazole, and from 2.5 to 100.0 µg kg-1 for sulfamerazine, sulfamonomethoxine and sulfadimethoxine. Limits of detection were between 2.5 and 5.0 µg kg-1. Recoveries of sulfonamides in milk samples ranged from 83.0 to 99.2% with RSDs lower than 6%. The developed composite adsorbent showed good reproducibility and reusability.

Development of extraction separation technology based on deep eutectic solvent and magnetic nanoparticles for determination of three sex hormones in milk.

A rapid, reliable and eco-friendly method for the determination of three sex hormones in five kinds of milk was developed and validated by combining vortex-assisted liquid-liquid microextraction (VALLME) and magnetic solid-phase extraction (MSPE). Deep eutectic solvents (DESs) such as choline chloride/urea were considered as the extraction solvent in VALLME and multi-walled carbon nanotubes (MMWCNTs) were used as the adsorbent which could adsorb DESs on the surface. The optimum experimental conditions were as follows: amount of MMWCNTs for 10 mg, volume of acetone for 4 mL, no sodium chloride and extraction pH at 7. After the optimization of several main variables, satisfactory sensitivity levels were achieved as low as 1.0-1.3 ng mL-1 and 2.5-4.5 ng mL-1 for the limit of method detections and the limit of method quantitation, respectively. The recoveries of the three hormones in different milk samples were in the range of 80.1%-116.4%. Consequently, this method is suitable for monitoring the trace amount of sex hormones in milk matrices.

Multiclass, Multiresidue Method for the Quantification and Confirmation of 112 Veterinary Drugs in Game Meat (Bison, Deer, Elk, and Rabbit) by Rapid Polarity Switching Liquid Chromatography-Tandem Mass Spectrometry.

An analytical program for multiclass, multiresidue residue analysis to qualitatively and quantitatively determine veterinary drug compounds in game meats by LC-MS/MS has been developed and validated. The method was validated for the analysis of muscle from bison, deer, elk, and rabbit to test for 112 veterinary drug residues from the following drug classes: ß-agonists, anthelmintics, anti-inflammatory drugs, corticosteroids, fluoroquinolones, ß-lactams, macrolides, nitroimidazoles, phenicols, polypeptides, sulfonamides, tetracyclines, thyreostats, and tranquilizers. Muscle was extracted using a simple and quick procedure based on a solvent extraction with 80% ACN/water and sample cleanup with dispersive solid-phase extraction. The compounds of interest were separated using a Waters HSS T3 column and detected by tandem mass spectrometry with rapid polarity switching to detect both negatively and positively charged ions in a single run. Recoveries were calculated using extracted matrix-matched calibration curves for each type of matrix. The average accuracy of fortified compounds ranged from 95.6 to 101% at the target quantitative validation level in the four matrices. The method was also validated as a qualitative screening method where all sample responses were compared with a single extracted matrix-matched calibrant at the target testing level (5 or 25 ng/g). Samples demonstrating a presumptive positive above the threshold value were re-extracted and analyzed with a five-point matrix-matching extracted calibration curve. Since the beginning of this survey program, 360 samples have been analyzed for veterinary drug residues in game meats. Antibiotic or tranquilizer residues have been identified in deer (chlortetracycline, haloperidol, and tulathromycin) and rabbit (sulfadiazine).

Determination of Polypeptide Antibiotic Residues in Food of Animal Origin by Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry.

A novel UHPLC-MS/MS method for the determination of polypeptide antibiotic residues in animal muscle, milk, and eggs was developed and validated. Bacitracin A, colistin A, colistin B, polymyxin B1, and polymyxin B2 were extracted from the samples with a mixture of acetonitrile/water/ammonia solution 25%, 80/10/10 (v/v/v), and put through further evaporation, reconstitution, and filtration steps. The chromatographic separation was performed on a C18 column in gradient elution mode. Mass spectral acquisitions were performed in selective multiple reaction monitoring mode by a triple quadrupole mass spectrometer. The method was validated according to the criteria of Commission Decision 2002/657/EC. The method quantifies polypeptides in a linear range from 10 to 1000 µg kg-1, where the lowest concentration on the calibration curve refers to the limit of quantification (LOQ). The recoveries ranged from 70 to 99%, the repeatability was below 13%, and within-laboratory reproducibility was lower than 15%. The decision limit (CCα) and detection capability (CCß) values were calculated, and ruggedness and stability studies were performed, to fulfill the criteria for confirmatory methods. Moreover, the developed method may also be used for screening purposes by its labor efficiency.

Simultaneous analysis of multiclass antibiotic residues in complex environmental matrices by liquid chromatography with tandem quadrupole mass spectrometry.

A simultaneous extraction and cleanup method was optimized and validated for the determination of 40 antibiotics from cephalosporin, fluoroquinolone, lincosamide, macrolide, nitroimidazole, quinolone, sulfonamide and tetracycline groups in sediments by liquid chromatography with tandem quadrupole mass spectrometry (LC-MS/MS). The method involved hydration of freeze-dried sediment sample (2.0 g) with 2.5 ml of 0.1 M Na-EDTA McIlvaine buffer and extraction with 5 ml of MeOH and MeCN (1:3 v/v) followed by dispersive solid phase extraction by using 100 mg mix of C18 and PSA (1:2 w/w) and 50 mg MgSO4 prior to LC-MS/MS analysis. The method was validated for 10, 20, 50 and 100 µg/kg spiking levels by using blank sediment sample obtained from a drinking water reservoir according to the guidelines of European Commission Decision (2002) 2002/657/EC. The method produced clean extracts with generally low matrix effect during LC-MS/MS analysis. The mean recoveries ranged between 24-162%, 48-151%, 51-159%, and 50-149% for 10, 20, 50 and 100 µg/kg spiking levels, respectively, with acceptable precision. The analytical method was sensitive enough to achieve 0.01-34.3 µg/kg and 0.03-115 µg/kg limits of detection and quantitation, respectively. The scope of the method was demonstrated by analyzing complex solid environmental matrices (chicken manure, swine manure, poultry feed and soil) spiked at 10, 20, 50 and 100 µg/kg levels. The method was also applied for the antibiotic analysis in samples with incurred residues. Different matrices in the order of the magnitude as sediments < poultry feed < swine manure < soil < chicken manure were detected with the residues of fluoroquinolone, macrolide, sulfonamide and tetracycline antibiotics.

Multiclass and multiresidue screening of veterinary drugs and pesticides in infant formula using Quadrupole-Orbitrap MS with PRM scan mode.

A multiclass and multiresidue method for screening veterinary drugs and pesticides in infant formula was developed and validated using ultrahigh-performance liquid chromatography coupled to Quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-HRMS). A total of 49 veterinary drugs and pesticides investigated belong to 11 classes including antivirals, anticoccidials, macrolides, pyrethroids, insecticides, sulfonamides, beta-agonists, sedatives, thyreostats, nonsteroidal anti-inflammatory drugs, and other pharmacologically active substances. A generic sample preparation and highly selective acquisition mode of parallel reaction monitoring (PRM) were deliberately incorporated to perform efficient screening analysis. As a result, the screening target concentrations of the analytes varied from 1 to 500 µg/kg with ≤5% of false compliant rate as specified in Decision 2002/657/EC for screening analysis. The average recoveries ranged from 40.7 to 124.9% as well as the relative standard deviations from 4.2 to 26.6%, respectively. The matrix effects and interferences were effectively controlled by integrated application of dispersive solid phase extraction, PRM scan mode, and matrix-matched standard calibration. The proposed method will be helpful to provide applicable strategy for screening residues in infant formula with surveillance purpose.

Preparation of porous magnetic molecularly imprinted polymers for fast and specifically extracting trace norfloxacin residue in pork liver.

Here, magnetic molecularly imprinted polymers were designed for norfloxacin via oil-in-water emulsifier-free emulsion method. It was prepared by simply mixing norfloxacin, methacrylic acid-co-ethylene glycol dimethacrylate copolymer, and Fe3 O4 together at room temperature. Characterized by multiple analytical tools, the particle size, pore size, pore volume, specific surface area, and saturation magnetization of the product were about 30 µm, 10-500 nm, 2.92 mL/g, 105.84 m2 /g, and 3.052 emu/g, respectively. And the adsorption capacity was high at 27.04 mg/g towards norfloxacin. Combined with ultra high performance liquid chromatography, it was used to determine norfloxacin in real samples. Average recoveries were above 77.44% with relative standard deviations between 1.21 and 6.85% at three spiked levels (n = 3) for lake water and pork liver. The determination was achieved for the most complex biosample pork liver spiked with norfloxacin low to 30 ng/g, about 100 times less than the maximum residue limit regulated by Commission of the European Communities. All evidences demonstrated that the magnetic molecularly imprinted polymers can be used in practice for monitoring norfloxacin either in environmental water or meat product with high accuracy and reliability.

Analysis of Major Components of Bacitracin, Colistin and Virginiamycin in Feed Using Matrix Solid-phase Dispersion Extraction by Liquid Chromatography-electrospray Ionization Tandem Mass Spectrometry.

A quantitative LC-MS/MS method has been developed for simultaneous determination of bacitracin A, bacitracin B, colistin A, colistin B and virginiamycin M1 in feed. This rapid simple and effective extraction method was based on matrix solid-phase dispersion. Qualitative and quantitative analyses were performed by LC-ESI-MS/MS. CCß of polypeptide antibiotics upon the method ranged from 9.6 to 15.8 µg kg-1 and 19.4 to 27.5 µg kg-1, respectively. The limit of quantification of polypeptide antibiotics was 25 µg kg-1 in feed samples. The recoveries of polypeptide antibiotics spiked in feed samples at a concentration range of 25-100 µg kg-1 were found above 75.9-87.9% with relative standard deviations within days less than 15.7% and between days less than 20.6%. This rapid and reliable method can be used to efficiently separate, characterize and quantify the residues of polypeptide antibiotics in feed with advantages of simple pretreatment and environmental friendly.

Chromatographic separation of racemic praziquantel and its residual determination in perch by LC-MS/MS.

An enantioselective depletion study of praziquantel (PZQ) in perch muscle was done using a simple, sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Two cyclic polypeptides and two cyclic saccharide chromatographic columns were evaluated. The new hydroxypropyl ß-cyclodextrin (HP-RSP) superficially porous particle (SPP) column produced the optimum separation and was selected for the study. Deuterium labeled PZQ-d11 was used as the internal standard. The method was linear over concentration ranges of 5.00-5.00×102µgL-1 (r2≥0.99) for (-)-R-PZQ and (+)-S-PZQ. The average recoveries of R-PZQ and S-PZQ at three spiked levels of 5.00, 50.00 and 5.00×102µgkg-1 ranged from 86.1% to 98.2%, and the intra-day and inter-day relative standard deviations were less than 5%. The decision limit (CCα) and detection capability (CCß) of R-PZQ and S-PZQ in perch muscle matrices were all 1.0µgkg-1 and 5.0µgkg-1, respectively. The method was successfully applied in monitoring the depletion of praziquantel enantiomers in perch muscle following oral administration. The elimination rate of R-PZQ and S-PZQ in perch muscle tissue is equivalent.

Synchronized separation, concentration and determination of trace sulfadiazine and sulfamethazine in food and environment by using polyoxyethylene lauryl ether-salt aqueous two-phase system coupled to high-performance liquid chromatography.

Polyoxyethylene lauryl ether (POELE10)-Na2C4H4O6 aqueous two-phase extraction system (ATPES) is a novel and green pretreatment technique to trace samples. ATPES coupled with high-performance liquid chromatography (HPLC) is used to analyze synchronously sulfadiazine (SDZ) and sulfamethazine (SMT) in animal by-products (i.e., egg and milk) and environmental water sample. It was found that the extraction efficiency (E%) and the enrichment factor (F) of SDZ and SMT were influenced by the types of salts, the concentration of salt, the concentration of POELE10 and the temperature. The orthogonal experimental design (OED) was adopted in the multi-factor experiment to determine the optimized conditions. The final optimal condition was as following: the concentration of POELE10 is 0.027gmL(-1), the concentration of Na2C4H4O6 is 0.180gmL(-1) and the temperature is 35°C. This POELE10-Na2C4H4O6 ATPS was applied to separate and enrich SDZ and SMT in real samples (i.e., water, egg and milk) under the optimal conditions, and it was found that the recovery of SDZ and SMT was 96.20-99.52% with RSD of 0.35-3.41%. The limit of detection (LOD) of this method for the SDZ and SMT in spiked samples was 2.52-3.64pgmL(-1), and the limit of quantitation (LOQ) of this method for the SDZ and SMT in spiked samples was 8.41-12.15pgmL(-1).

Magnetic nanoparticles based dispersive micro-solid-phase extraction as a novel technique for the determination of estrogens in pork samples.

A simple and rapid magnetic nanoparticles (MNPs) based dispersive micro-solid-phase extraction (D-µ-SPE) method coupled with HPLC-DAD has been proposed for simultaneous determination of three estrogens (17ß-estradiol (E2), estrone (E1) and diethylstilbestrol (DES)) in pork samples. In this paper, the synthesis of cetyltrimethyl ammonium bromide (CTAB)-coated Fe3O4@caprylic acid NPs as an efficient sorbent for its high surface area, excellent adsorption capacity, good dispersion ability and high super-paramagnetic property was successfully applied to adsorb estrogens. Vortex was used to enhance mass transfer rate as it provided mild and effective mixing of sample solution and increased the contact between analytes and MNPs. The parameters affecting the extraction efficiency were investigated in detail. The dosages of sorbent and eluate are 100µL and 500µL, respectively. The extraction equilibrium was achieved within 2min and the MNPs can be reused. The proposed technique provided high recoveries (93.3-106.7%), good linearity (0.9993-0.9999), low LODs (0.021-0.033ngmL(-1)) and repeatability (RSD%=1.87-2.92).

Rapid Determination of Clenbuterol in Pork by Direct Immersion Solid-Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry.

Direct immersion solid-phase microextraction (DI-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was developed for rapid analysis of clenbuterol in pork for the first time. In this work, a low-cost homemade 44 µm polydimethylsiloxane (PDMS) SPME fiber was employed to extract clenbuterol in pork. After extraction, derivatization was performed by suspending the fiber in the headspace of the 2 mL sample vial saturated with a vapor of 100 µL hexamethyldisilazane. Lastly, the fiber was directly introduced to GC-MS for analysis. All parameters that influenced absorption (extraction time), derivatization (derivatization reagent, time and temperature) and desorption (desorption time) were optimized. Under optimized conditions, the method offered a wide linear range (10-1000 ng g(-1)) and a low detection limit (3.6 ng g(-1)). Finally, the method was successfully applied in the analysis of pork from the market, and recoveries of the method for spiked pork were 97.4-105.7%. Compared with the traditional solvent extraction method, the proposed method was much cheaper and fast.

Nickel Oxide Nanoparticle-Deposited Silica Composite Solid-Phase Extraction for Benzimidazole Residue Analysis in Milk and Eggs by Liquid Chromatography-Mass Spectrometry.

A novel nickel oxide nanoparticle-deposited silica (SiO2@NiO) composite was prepared via liquid-phase deposition (LPD) and then employed as a solid-phase extraction (SPE) sorbent. When the SPE was coupled with liquid chromatography-electrospray ionization mass spectrometry (LC-ESI/MS) analysis, an analytical platform for the sensitive determination of benzimidazole residues in egg and milk was established. The limits of detection of nine benzimidazoles were in the range of 0.8-2.2 ng/mL in milk and 0.3-2.1 ng/g in eggs, respectively, which was 5-10 times superior to the methods with other adsorbents for SPE. The recoveries of nine benzimidazoles spiked in milk and egg ranged from 70.8 to 118.7%, with relative standard deviations (RSDs) being less than 18.9%. This work presented the excellent extraction performance of NiO on benzimidazoles for the first time, and the applicability of the LPD technique used as sorbents for trace analysis in complex matrices was also demonstrated.

In vivo studies to highlight possible illegal treatments of rabbits with carbadox and olaquindox.

For the treatment of rabbit dysentery and bacterial enteritis, veterinary practitioners often adopt veterinary medicinal products authorised for other food-producing species, but in some cases non-authorised drugs frequently used in the past, such as carbadox and olaquindox, might be illegally adopted. To verify the carbadox and olaquindox distribution and persistence in rabbit tissues, two independent in vivo studies were carried out. In the first study, 24 healthy rabbits received water medicated with carbadox at 100 mg l(-1) over a period 28 days, whereas in the second one, 24 healthy rabbits were administered water containing olaquindox at 100 mg l(-1). In each study rabbits were randomly assigned to four groups to be sacrificed respectively at 0, 5, 10 and 20 days from treatment withdrawal, for depletion studies. A control group of six animals was adopted for control and as a reservoir of blank tissues. Muscle and liver samples collected from each treated animal were stored at -20°C pending the analysis. Sensitive and robust liquid chromatography-tandem mass spectrometry analytical methods were set up for the parent compounds and their main metabolites quinoxaline-2-carboxylic acid, desoxycarbadox and 3-methylquinoxaline-2-carboxylic acid to verify their residual. Data collected demonstrate that the combination of liver as target matrix, quinoxaline-2-carboxylic acid and 3-methylquinoxaline-2-carboxylic acid as marker residue and enzymatic digestion is strategic to evidence carbadox and/or olaquindox illegal treatments in rabbits, even 20 days after treatment withdrawal at concentration levels higher than 0.5 µg kg(-1). This findings suggests that liver should be proposed as target matrix for official control in national monitoring plan.

Determination of cyflumetofen residue in water, soil, and fruits by modified quick, easy, cheap, effective, rugged, and safe method coupled to gas chromatography/tandem mass spectrometry.

A new, highly sensitive, and selective method was developed for the determination of the cyflumetofen residue in water, soil, and fruits by using gas chromatography quadruple mass spectrometry. The target compound was extracted using acetonitrile and then cleaned up using dispersive solid-phase extraction with primary and secondary amine and graphitized carbon black, and optionally by a freezing-out cleanup step. The matrix-matched standards gave satisfactory recoveries and relative standard deviation values in different matrices at three fortified levels (0.05, 0.5, and 1.0 mg kg(-1) ). The overall average recoveries for this method in water, soil, and all fruits matrix at three fortified levels ranged from 76.3 to 101.5% with relative standard deviations in the range of 1.2-11.8% (n = 5). The calculated limits of detection and quantification were typically below 0.005 and 0.015 µg kg(-1), which were much lower than the maximum residue levels established by Japanese Positive List. This study provides a theoretical basis for China to draw up maximum residue level and analytical method for cyflumetofen acaricide in different fruits.

Multi-residue analysis of free and conjugated hormones and endocrine disruptors in rat testis by QuEChERS-based extraction and LC-MS/MS.

Endocrine disrupting compounds (EDCs) are suspected to be responsible for many disorders of the human reproductive system. To establish a causality relationship between exposure to endocrine disruptors and disease, experiments on animals must be performed with improved or new analytical tools. Therefore, a simple, rapid, and effective multi-residue method was developed for the determination of four steroid hormones (i.e., testosterone, androstenedione, estrone, and estradiol), glucuronide and sulfate conjugates of estrone and estradiol and four endocrine disruptors in rat testis (i.e., bisphenol A, atrazine, and active metabolites of methoxychlor and vinclozolin). The sample preparation procedure was based on the Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) approach. An analytical method was then developed to quantify these compounds at ultra-trace levels by liquid chromatography coupled to tandem mass spectrometry. The QuEChERS extraction was optimized with regard to the acetonitrile/water ratio used in the extraction step, the choice of the cleanup method and the acetonitrile/hexane ratio used in the cleanup step. The optimized extraction method exhibited recoveries between 89% and 108% for all tested compounds except the conjugates (31% to 58%). The detection limits of all compounds were below 20 ng g(-1) of wet weight of testis. The method was subsequently applied to determine the levels of hormones and EDCs in seven rat testis samples.

A liquid chromatography tandem mass spectrometry method for simultaneous determination of acid/alkaline phytohormones in grapes.

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for simultaneous determination of five acid/alkaline phytohormones, i.e., indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), naphthylacetic acid (NAA), gibberellic acid (GA(3)) and isopentenyladenine (2IP), in grapes was developed. After optimization, the samples were extracted with methanol containing 1% formic acid and purified by Oasis HLB SPE cartridges. The analytes were separated on a Thermo Hypersil Gold column (100 mm×2.1 mm, 3.0 µm) with water and acetonitrile, then determined with Thermo tandem quadrupole mass spectrometer operating in negative electro-spray ionization using selected reaction monitoring (SRM) mode. The established method was further validated by determining the linearity (R² ≥ 0.9990), average recovery (82.5-105.4%), sensitivity (0.05-1.00 ng mL⁻¹), precision (RSD ≤1 3.0%) and stability (RSD ≥ 82.0%). Finally, the application of the approach proposed to thirty grape samples convinced its desirable performance for rapid analysis of multiclass phytohormones, supporting its sufficient capability for multiresidue analyses or other analytical system targeting phytohormones in agriculture field.

Trace analysis of acidic pharmaceutical residues in waters with isotope dilution gas chromatography-mass spectrometry via methylation derivatization.

Acidic pharmaceutical residues are pollutants of emerging concern and are generally monitored by HPLC-MS/MS. However, due to the limited separation efficiency of HPLC column and lack of suitable mass transition for confirmation analysis, some interference may not be separated completely and differentiated from ibuprofen, which may cause the results with interference, especially in sample with complex matrix. The objective of this study is to develop a sensitive and reliable method for the determination of acidic pharmaceutical residues in water samples by GC-MS with better resolution by using methylation derivatization and isotope dilution techniques. TMSDM, a mild reagent, was used as the derivatization reagent coupling with the isotope dilution technique, for the first time, to improve the precision and accuracy of the analytical method to determine the pharmaceutical residues in water. The MDLs for the five acidic organic compounds: ibuprofen, gemfibrozil, naproxen, ketoprofen and diclofenac were from 0.7 to 1.1 ng/L, with recoveries ranging from 93 to 110%. Alternative to the HPLC-MS/MS method, the developed GC-MS protocols provides an additional option for the analysis of acidic pharmaceutical residues in water, with better separation efficiency in reducing interferences from complicated sample matrix, for determination of ibuprofen residues.

Development of a multi-residue method for the determination of organic micropollutants in water, sediment and mussels using gas chromatography-tandem mass spectrometry.

This study describes the development of a multiresidue method based on gas chromatography-electron ionization-tandem mass spectrometry (GC-EI-MS/MS) for the detection of sixteen polycyclic aromatic hydrocarbons (PAHs), five phthalate esters (PEs), seven polychlorinated biphenyls (PCBs), six polybrominated diphenyl ethers (PBDEs), six alkylphenols (APs), three organochlorined pesticides and their isomers or degradation products (OCPs) and bisphenol A in seawater, river water, wastewater treatment plant (WWTP) effluents, sediments and mussels. Solid phase extraction (SPE) was used for the extraction of target analytes in aqueous samples, and ultrasound assisted extraction for solid samples. GC-EI-MS/MS acquisition conditions in selected reaction monitoring (SRM) using two transitions per compound were optimized. In this way, quantification and unequivocal identification of organic micropollutants were performed in compliance with the Decision 2002/657/EC. Good linearity responses with coefficients of determination higher than 0.99 were obtained. Methodological detection limits (MDLs) in seawater ranged from 0.1 to 6 ng L(-1); in river water from 0.1 to 4.8 ng L(-1); in WWTP effluents from 1 to 75 ng L(-1); in sediments from 1 to 150 ng g(-1) and in mussels from 1 to 125 ng g(-1). MDLs and recovery yields were compared with other published methods and similarities or even improvements were achieved. The optimized method was applied to analyze five samples from each matrix collected in coastal areas, showing its potential use for marine pollution monitoring.

Dispersive liquid-liquid microextraction using non-chlorinated, lighter than water solvents for gas chromatography-mass spectrometry determination of fungicides in wine.

A novel and low solvent consumption method for the sensitive determination of fungicide residues in wine samples is proposed. Analytes were extracted by dispersive liquid-liquid microextraction (DLLME) and further determined by gas chromatography-mass spectrometry (GC-MS). Under optimized conditions, a binary mixture of acetone and 1-undecanol (0.5 and 0.05 mL, respectively) was used to extract target compounds from diluted (1:1) wine samples. After centrifugation, the floating phase of 1-undecanol was solidified and separated from the liquid hydro-alcoholic matrix. Thereafter, it was allowed to melt at room temperature and injected in the GC-MS system. The method showed relative standard deviations (RSDs, %) below 13%, limits of quantification (LOQs) between 0.2 and 3.2 ng mL(-1) and linear responses for concentrations up to 300 ng mL(-1). The efficiency of the liquid-phase microextraction process was scarcely affected by the characteristics of wine samples, consequently pseudo-external standard calibration (using matrix matched standards of red and white wine) sufficed to achieve acceptable accuracy values: relative recoveries from 81 to 120%. The applicability of the method was demonstrated with commercial wine samples.