The pesticide residue analysis in commodities with high content of chlorophyll based on the quick, easy, cheap, effective, rugged, and safe method: A review.

In multiresidue analysis, the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) is one of the most popular techniques routinely used by researchers during pesticide analysis of food and vegetable samples. Originally, the QuEChERS method was developed for analysis of pesticide residues from fruits and vegetables, but rapidly gained popularity in the extraction of analytes from different matrices. This analytical approach shows several advantages over traditional extraction techniques: it requires lower sample and solvent amounts while shortening the time of sample preparation. However, it presents some limitations for complex matrices such as those containing high amounts of chlorophyll. To overcome the problem of strong matrix effect and influence of interferences, different approaches are applied. Most are concerning modifications of the cleanup step, that is, sorbent type and its amount. Optimization of other parameters, such as sample size, hydration level, extraction solvent, and buffering, also has an impact on overall performance. Combining proper sample preparation with modern highly sensitive and selective detection techniques enables receiving desired limits of quantification. This article presents an overview of strategies employed by researchers for analysis of green, high chlorophyll content commodities and results obtained in their studies.

Rapid quantification of fatty acids in plant oils and biological samples by LC-MS.

Analysis of fatty acids (FA) in food and biological samples such as blood is indispensable in modern life sciences. We developed a rapid, sensitive and comprehensive method for the quantification of 41 saturated and unsaturated fatty acids by means of LC-MS. Optimized chromatographic separation of isobaric analytes was carried out on a C8 reversed phase analytical column (100 × 2.1 mm, 2.6 µm core-shell particle) with a total run time of 15 min with back pressure lower than 300 bar. On an old triple quadrupole instrument (3200, AB Sciex), pseudo selected reaction monitoring mode was used for quantification of the poorly fragmenting FA, yielding limits of detection of 5-100 nM. Sample preparation was carried out by removal of phospholipids and triglycerides by solid-phase extraction (non-esterified fatty acids in oils) or saponification in iso-propanol (fatty acyls). This is not only a rapid strategy for quantification of fatty acyls, but allows the direct combination with the LC-MS-based analysis of fatty acid oxidation products (eicosanoids and other oxylipins) from the same sample. The concentrations of fatty acyls determined by means of LC-MS were consistent with those from GC-FID analysis demonstrating the accuracy of the developed method. Moreover, the method shows high precisions with a low intra-day (≤ 10% for almost all fatty acids in plasma and ≤ 15% in oils) and inter-day as well as inter-operator variability (< 20%). The method was successfully applied on human plasma and edible oils. The possibility to quantify non-esterified fatty acids in samples containing an excess of triacylglycerols and phospholipids is a major strength of the described approach allowing to gain new insights in the composition of biological samples.

QuEChERS and 96-well plate solid phase extraction for determination of vancomycin and norvancomycin in fish meat by UPLC-MS/MS.

Vancomycin and norvancomycin are glycopeptide antibiotics for gram-positive bacteria infection, but indiscriminately used in aquaculture. In this study, a QuEChERS (quick, easy, cheap, effective, rugged, and safe)/96-well solid-phase extraction (SPE) plate method was used to extract vancomycin and norvancomycin in fish meat samples, and the drugs were further analyzed by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The parameters, such as the sorbent of cation exchange resin, the proportion of acetonitrile (15%) in extractant, the mobile phase of water (0.1% formic acid)/acetonitrile, were optimized. The method was validated in terms of linearity (0.9990-0.9994), LOD (0.51 µg·kg-1), LOQ (1.73 µg·kg-1), intra-dayprecision (<5.19%), inter-day precision (<6.30%), and recovery (86.7-98.6%). Finally, the method was successfully applied to contaminated and randomly collected samples. The results indicated that the proposed method meet the daily monitoring requirements for vancomycin and norvancomycin.

UltraPrep is a scalable, cost-effective, bead-based method for purifying cell-free DNA.

UltraPrep is an open-source, two-step method for purification of cell-free DNA that entails extraction of total DNA followed by size-selective enrichment of the smaller fragments that are characteristic of DNA originating from fragmentation between nucleosome. The advantages of the two related protocols that are described are that they can easily accommodate a wide range of sample input volumes, they rely on simple, magnetic bead-based technology, the yields of cfDNA are directly comparable to the most popular methods for cfDNA purification, and they dramatically reduce the cost of cfDNA isolation relative to currently available commercial methods. We provide a framework for physical and molecular quality analysis of purified cfDNA and demonstrate that the cfDNA generated by UltraPrep meets or exceeds the quality metrics of the most commonly used procedure. In addition, our method removes high molecular weight genomic DNA (hmwgDNA) that can interfere with downstream assay results, thereby addressing one of the primary concerns for preanalytical collection of blood samples.

Magnetic solid-phase extraction modified Quick, Easy, Cheap, Effective, Rugged and Safe method combined with pre-column derivatization and ultra-high performance liquid chromatography-tandem mass spectrometry for determination of estrogens and estrogen mimics in pork and chicken samples.

In this study, conventional Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method was modified by magnetic solid-phase extraction (MSPE) for purification/pre-concentration of eleven estrogens and estrogen mimics from the extracts of pork and chicken muscles, prior to dansyl chloride (DNS-Cl) derivatization coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) assay. Dual octadecyl- and 2-aminoethyl-3-aminopropyl- groups functionalized mesoporous silica core-shell magnetic nanoparticles (C18/NH2-Fe3O4@mSiO2 MNPs) were synthesized and employed as MSPE sorbent with remarkable aqueous compatibility in comparison with conventional C18 functionalized sorbent. The proposed MSPE is easier to handle than the traditional SPE purification process in QuEChERS method. The lab-prepared MNPs were characterized by transmission electron microscope (TEM), brunner-emmet-teller (BET), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA) and vibrating sample magnetometer (VSM). Pre-column derivatization was conducted to significantly enhance the sensitivity of the analytes in MS/MS via analyzing their derivatives in positive ion mode instead of analyzing their original forms in negative ion mode. Under the optimal sample pretreatment and instrumental analysis conditions, the approach showed low limits of detection (LODs, 0.02‒3.00 µg kg-1), appropriate recoveries (81.1‒115.4%) and acceptable precisions (0.48‒15.1%, n = 6), with good feasibility and future prospect of trace compounds analysis in complex food samples.

A sensitive and cost-effective high-performance liquid chromatography/tandem mass spectrometry (multiple reaction monitoring) method for the clinical measurement of serum hepcidin.

RATIONALE: Hepcidin is a peptide hormone that plays a central role in regulating iron metabolism. It is a potential biomarker for the diagnosis, monitoring and treatment of iron metabolism disorders. Serum hepcidin level can differ by 3 orders of magnitude depending on the patient's condition. Existing liquid chromatography/mass spectrometry (LC/MS) assays lack clinical sensitivity or require costly sample preparation steps. A simple, sensitive, robust and cost-effective assay for serum hepcidin quantitation in routine clinical laboratories is needed. METHODS: A high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) method was developed to quantify hepcidin in human serum using chemically synthesized hepcidin as a standard and stable-isotope-labeled hepcidin as the internal standard. The method was validated according to CLSI-C62A guidelines. Calibrators were prepared with hepcidin-free serum. Clinical samples were separately processed and compared using solid-phase extraction (SPE) and acetonitrile (ACN) protein precipitation. RESULTS: The calibration curve was validated over the range of 0.1-100 nmol/L with R2  >0.99. Both the SPE and the ACN precipitation methods had excellent and comparable reproducibility. The intra-day and inter-day coefficients of variation (CVs) were <3% and <6%. There was 89% and 88% hepcidin recovery by SPE and ACN preparation. Measurement of secondary reference material using non-traceable calibrators yielded up to 30% positive bias, comparable with values obtained by an external comparator. Hepcidin was stable in serum at ambient temperature and at 4°C. The relative errors (REs) were ≤1.2% and ≤4.4%, respectively. The freeze-thaw (-70°C) stability after 3 cycles showed a relative error (RE) of ≤1.8%. The impact on hepcidin recovery due to hemolysis (4+), lipemia (4+) and Icterus (4+) was <3%. CONCLUSIONS: We have developed and validated a simple, sensitive, robust and cost-effective HPLC/MS/MS method for the quantitation of serum hepcidin. The method uses ACN protein precipitation for sample preparation and reversed-phase normal-flow HPLC. Sample preparation is inexpensive; it can be automated with a liquid handling system to allow high-throughput application.

Synthesis of chitosan based molecularly imprinted polymer for pipette-tip solid phase extraction of Rhodamine B from chili powder samples.

The purpose work is devoted to design of a simple, one-pot and green approach for the synthesis of molecularly imprinted polymer to construct a selective sorbent for pipette-tip solid phase extraction of Rhodamine B from chili powder samples and its subsequence separation and quantification by high performance liquid chromatography-ultraviolet/visible detection. The prepared molecularly imprinted polymer was synthesized using chitosan as versatile natural multi-functional bio-monomer and Rhodamine B as template in aqueous media. The effects of influential parameters (sorbent dosage, flow rate and eluent solvent volume) and their influences on Rhodamine B extraction recovery were examined and optimized by central composite design based response surface methodology as a powerful multivariate optimization tool. Under the optimized conditions, the linear range and limit of detection and quantification of proposed method were achieved to be 0.005-15 mg kg-1, 0.0015 mg kg-1 and 0.00488 mg kg-1, respectively, with satisfactory recoveries (>85.0%) and excellent repeatability (relative standard deviation < 6.1%). The easy synthesis conditions as well as satisfactory figures of merit are good indication of applicability of suggested method for extraction and determination of Rhodamine B from chili powder samples in terms of simplicity, cost effectiveness, selectivity and accurate analysis.

Development of rapid, sensitive and selective fluorimetric method for determination of 1-naphthalene acetic acid in cucumber by using magnetite-molecularly imprinted polymer.

In this study, a novel method based on the determination of 1-naphthalene acetic acid with the usage of magnetite-molecularly imprinted polymer prior to fluorimetric detection has been developed. Magnetite-molecularly imprinted polymer has been used for the first time as selective adsorbent for the determination of 1-naphthalene acetic acid. The adsorption capacity of the synthesized polymer was found to be 2.18 ±â€¯0.36 mg g-1 (n = 3). Limit of detection (LOD) and limit of quantification (LOQ) of the method were found to be 0.75 and 2.50 µg L-1, respectively. Linearity of the calibration graph for the proposed method was observed within the range of 20-700 µg L-1. The proposed method seems to be rapid where the detection procedure for 1-naphthalene acetic acid can be completed within a total time of 1 h. The same imprinted polymer can be used for the determination of 1-naphthalene acetic acid with quantitative sorption and recovery values repeatedly for at least ten times. The effects of some potential organic interferences were investigated. Proposed method has been successfully applied to determine 1-naphthalene acetic acid in cucumber, where the recoveries of the spiked samples were found to be in the range of 93.7-104.5%. Characterization of the synthesized polymer was also evaluated. By combining the high capacity, cheapness, reusability and selectivity of the magnetic adsorbent with the dynamic calibration range, rapidity, simplicity, and sensitivity of fluorimetry, the proposed method seems to be an ideal method for the determination of trace levels of 1-naphthalene acetic acid.

Clay-Na as a sorbent for the extraction of anti-inflammatory compounds in water samples.

In this work, clay-Na particles are used as the adsorbent for the solid-phase extraction of acidic compounds. The novel sorbent under study is based on high-specific surface area, cation-exchange capacity designed specifically to offer ion-exchange properties with the goal being to selectively extract a group of acidic compounds. The effects of the extraction parameters including extraction elution solvent, sample volume and pH. In optimum conditions, the repeatability for one fiber (n = 3), expressed as % relative standard deviation, was between 0.3 and 4.3% for the acid compounds. The detection limits for the studied acidic compounds were between 0.1-0.6 µg/L. The developed method offers the advantages of being simple to use and having a low cost of equipment.

Synthetic Peptide Purification via Solid-Phase Extraction with Gradient Elution: A Simple, Economical, Fast, and Efficient Methodology.

A methodology was implemented for purifying peptides in one chromatographic run via solid-phase extraction (SPE), reverse phase mode (RP), and gradient elution, obtaining high-purity products with good yields. Crude peptides were analyzed by reverse phase high performance liquid chromatography and a new mathematical model based on its retention time was developed in order to predict the percentage of organic modifier in which the peptide will elute in RP-SPE. This information was used for designing the elution program of each molecule. It was possible to purify peptides with different physicochemical properties, showing that this method is versatile and requires low solvent consumption, making it the least polluting one. Reverse phase-SPE can easily be routinely implemented. It is an alternative to enrich and purified synthetic or natural molecules.

Cost-effective imprinting to minimize consumption of template in room-temperature ionic liquid for fast purification of chlorogenic acid from the extract of E. ulmoides leaves.

One of the main challenges in large-scale applications of molecularly imprinted polymers (MIPs) is the significant amount of template needed in polymer preparation. A new strategy based on room-temperature ionic liquids (RTILs) was suggested to solve this problem by reducing the amount of template in the polymerization recipe. The MIP was synthesized with a mixture of dimethyl sulfoxide and RTIL (1-butyl-3-methylimidazolium tetrafluoroborate) as porogen, in which chlorogenic acid (CGA) was used as template, 4-vinylpyridine (4-VP) as functional monomer, and ethylene glycol dimethacrylate (EDMA) as cross-linker. The influence of polymerization variables, including CGA concentrations, and the ratio of 4-VP to EDMA on imprinting effect were investigated comprehensively. Moreover, the properties involving the column permeability, the number of binding sites, and the polymer morphology of the CGA-MIP monoliths were studied thoroughly. The MIP monolith had an excellent column permeability (1.53 × 10-13 m2) and allowed an ultra-fast on-line SPE, which dramatically shortens the separation time (< 10 min) and improves the separation efficiency. At high flow velocity (5.0 mL min-1), 50 µL of the extract from Eucommia ulmoides leaves can be loaded directly on the CGA-MIP monoliths and CGA with high purity can be obtained with a recovery of 89.01 ± 0.05%. As a conclusion, the resulting RTIL-induced approach of preparing MIP may be an effective tool in fabricating MIP in a low-cost way. Graphical abstract ᅟ.

[Evaluation of the capillary assay of C-reactive protein (CRP) through the lenght of consultation in pediatric emergencies and its economic impact]. / Évaluation du dosage capillaire de la protéine C-réactive (CRP) sur la durée de consultation aux urgences pédiatriques et impact économique.

Fever is a frequent reason for consultation in pediatric emergency departments and raises the question of biological and radiological examinations. Rapidly obtaining the result of C-reactive protein (CRP) level is essential in front of the steady increase of the number of visits. We carried out a prospective study within the pediatric emergency department of the University Hospital of Clermont-Ferrand from January to April 2017, in order to evaluate the interest of the capillary CRP in point of care (POCT). In two periods, 68 patients (28 controls without and 40 cases with capillary CRP assayed on a Afinion® AS100) with naked fever greater than 48 hours were included. After a study of the analytical performances of Afinion® and a verification of the homogeneity and the comparability of the two groups on clinical criteria (age, sex, duration of the fever, antibiotics treatment) and biological (values of CRP), the interest of the CRP in POCT was evaluated. In the POCT group, a significant drop in the median of the emergency room consultation time (60 (IQR 33-125) versus 180 (IQR 158-208) minutes), the number of biological acts by patient (1 (IQR 1-3) versus 7 (IQR 3-8)), the global cost of biological and radiological examinations per patient (5.4 (IQR 5.4-32.6) versus 153.8 (IQR 46.9-180.4) euros), and the cost of reagents spent by the laboratory per patient (5.2 (IQR 5.2-6.4) versus 33.2 (IQR 2.3-34.2) euros). Thus, in the context of a clinical-biological partnership, the use of CRP in POCT present a practical and an economic interest.

Rapid monitoring of plant growth regulators in bean sprouts via automated on-line polymeric monolith solid-phase extraction coupled with liquid chromatography tandem mass spectrometry.

An automated on-line solid-phase extraction (SPE) following liquid chromatography tandem mass spectrometry was established for the fast determination of plant growth regulator residues in soybean sprout and mung bean sprout. The crude extracted specimens were directly purified on a poly (2-(dimethylamino) ethyl methacrylate-co-ethylene dimethacrylate) monolithic column which was well-defined as the on-line SPE adsorbent. Under the optimized conditions, the developed method gave the linear range of 0.3-50 ng/mL for gibberellin and 2,4-dichlorophenoxyacetic acid, 0.2-50 ng/mL for 4-chlorophenoxyacetic acid, and 0.5-50 ng/mL for 1-naphthaleneacetic acid (r ≥ 0.998). The detection limits (S/N = 3) ranged from 1.0 to 2.5 µg/kg and the recoveries for spiked soybean sprout samples were in the range of 75.0-93.3%. Besides, the total time for one analysis was 16 min. The reusability of the monolith was up to 600 extractions. The proposed process facilitated fully automated SPE and accurate determination in one step with rapidity, simplicity, and reliability. Graphical abstract ᅟ.

Determination of six benzotriazole ultraviolet filters in water and cosmetic samples by graphene sponge-based solid-phase extraction followed by high-performance liquid chromatography.

An approach for fabrication of graphene sponge (GS)-based solid-phase extraction (SPE) followed by high-performance liquid chromatography (HPLC) with ultraviolet detection (HPLC-UV) is proposed, which was applied to determine the six benzotriazole UV filters in water and cosmetic samples. Several extraction conditions including type of elution solvent, the volume of elution solvent, and salt effect were optimized. Under the optimum conditions, the GS-SPE-HPLC-UV method shows a low limit of detection (LOD, S/N = 3) of 0.02-0.08 µg L-1 for standard solution, limits of quantification (LOQ, S/N = 10) of 0.07-0.26 µg L-1 for standard solution, wide linear ranges from 20.0 to 1000 µg L-1 for all compounds for standard solution, correlation coefficients (r) of more than 0.999, except for 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (UV-P), and acceptable reproducibility (relative standard deviations, RSDs < 6.5% for intra-day, RSDs < 8.1% for inter-day). The satisfactory recoveries were obtained in the range 89-105% with RSDs lower than 9.8% at the three spiked levels of 20, 50, and 100 µg L-1. Every home-made GS-SPE cartridge can be reused for more than 60 cycles. The method is facile, low-cost, rapid, sensitive, and suitable for the determination of UV filters in water and cosmetics samples. Graphical abstract ᅟ.

Inexpensive, effective novel activated carbon fibers for sample cleanup: application to multipesticide residue analysis in food commodities using a QuEChERS method.

Phenolic resin based activated carbon fibers (ACFs) were applied for the first time as a reversed-dispersive solid-phase extraction (r-DSPE) sorbent. A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was applied to determine 26 pesticides (organophosphates, organochlorines, synthetic pyrethroids, and herbicides) in different complex matrices, including cauliflower, cucumber, banana, apple, wheat, and black gram. Different physicochemical characterization techniques were used to investigate the engineering and structural properties of the r-DSPE sorbent. All the chromatographic analyses were performed with a gas chromatograph equipped with an electron capture detector. The recoveries of all 26 pesticides were acceptable (70-120%), with relative standard deviations of less than 15%. The limit of detection and the limit of quantification were 1.13-5.48 ng/g and 3.42-16.60 ng/g, respectively. In the original QuEChERS method, primary secondary amine is extensively used as the r-DSPE sorbent in the cleanup process, but it is eightfold more expensive than the ACFs used in this study. Therefore, the modified QuEChERS method using ACFs during the cleanup process is more efficient, cheaper, and more robust to determine pesticides from different types of matrices, including vegetables, grains, and fruits, and ACFs could be used as a cost-effective alternative to primary secondary amine. Graphical Abstract Sample clean-up using PSA and ACF as r-DSPE sorbent in QuEChERS method.

Rapid, low temperature synthesis of molecularly imprinted covalent organic frameworks for the highly selective extraction of cyano pyrethroids from plant samples.

New imine-linked molecularly imprinted covalent organic frameworks (MICOFs) were successfully prepared, using fenvalerate as the dummy template. Schiff base reaction between 1,3,5-tris(4-aminophenyl)benzene and 1,3,5-triformylphloroglucinol was rapidly achieved at room temperature, using Sc(OTf)3 as the catalyst. The surface groups and morphologies of MICOFs were assessed by Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface area analysis, and scanning electron microscopy. The MICOFs exhibited high selectivity toward four structurally similar cyano pyrethroids, including fenvalerate, flucythrinate, ß-cyfluthrin and λ-cyhalothrin. A method based on solid phase extraction using MICOFs coupled to high performance liquid chromatography was established for the determination of cyano pyrethroids in plant samples. Linearity in the range 0.1-200 ng g-1, with correlation coefficients of 0.9981-0.9993, was obtained for the four cyano pyrethroids. Detection limits and quantification limits were in the range 0.011-0.018 ng g-1 and 0.036-0.060 ng g-1, respectively. Recoveries at three spiked levels ranged from 94.3% to 102.7%. The developed method is thus a promising technique for the selective extraction of cyano pyrethroids from complex matrices.

Automated Online Solid-Phase Derivatization for Sensitive Quantification of Endogenous S-Nitrosoglutathione and Rapid Capture of Other Low-Molecular-Mass S-Nitrosothiols.

S-Nitrosothiols (RSNOs) constitute a circulating endogenous reservoir of nitric oxide and have important biological activities. In this study, an online coupling of solid-phase derivatization (SPD) with liquid chromatography-mass spectrometry (LC-MS) was developed and applied in the analysis of low-molecular-mass RSNOs. A derivatizing-reagent-modified polymer monolithic column was prepared and adapted for online SPD-LC-MS. Analytes from the LC autosampler flowed through the monolithic column for derivatization and then directly into the LC-MS for analysis. This integration of the online derivatization, LC separation, and MS detection facilitated system automation, allowing rapid, laborsaving, and sensitive detection of RSNOs. S-Nitrosoglutathione (GSNO) was quantified using this automated online method with good linearity (R2 = 0.9994); the limit of detection was 0.015 nM. The online SPD-LC-MS method has been used to determine GSNO levels in mouse samples, 138 ± 13.2 nM of endogenous GSNO was detected in mouse plasma. Besides, the GSNO concentrations in liver (64.8 ± 11.3 pmol/mg protein), kidney (47.2 ± 6.1 pmol/mg protein), heart (8.9 ± 1.8 pmol/mg protein), muscle (1.9 ± 0.3 pmol/mg protein), hippocampus (5.3 ± 0.9 pmol/mg protein), striatum (6.7 ± 0.6 pmol/mg protein), cerebellum (31.4 ± 6.5 pmol/mg protein), and cortex (47.9 ± 4.6 pmol/mg protein) were also successfully quantified. When the derivatization was performed within 8 min, followed by LC-MS detection, samples could be rapidly analyzed compared with the offline manual method. Other low-molecular-mass RSNOs, such as S-nitrosocysteine and S-nitrosocysteinylglycine, were captured by rapid precursor-ion scanning, showing that the proposed method is a potentially powerful tool for capture, identification, and quantification of RSNOs in biological samples.

Multianalyte, high-throughput liquid chromatography tandem mass spectrometry method for the sensitive determination of fungicides and insecticides in wine.

Evidence of pesticide transfer from grapes to wine, added to differences in the national regulations regarding the number and the maximum concentration of these species in wine, demands analytical procedures suitable for their routine control in this foodstuff. In this research, solid-phase extraction (SPE) and ultra-performance liquid chromatography (UPLC), with tandem mass spectrometry (MS/MS) detection, are combined to obtain a sensitive and rapid procedure to determine 50 pesticides in red and white wines. Efficiency and selectivity of sample preparation are correlated with the type of sorbent, the elution solvent, and the physicochemical properties of pesticides. SPE of 2-mL wine samples followed by direct injection of the extract in the UPLC-MS/MS system provides quantification limits (LOQs) below 1 ng mL-1 for 48 out of 50 compounds, linear responses up to 200 ng mL-1, and acceptable accuracy, employing quantification against solvent-based standards, for 45 species. A total analysis time of 10 min, including compounds separation and re-equilibration of the UPLC column, was achieved. The developed methodology was applied to 25 wines (20 conventional and 5 ecological), produced in 7 different countries. Out of 27 pesticides quantified in these wines, 12 displayed occurrence frequencies above 24%; moreover, all wines, except one of the ecological ones, contained residues from at least one pesticide.

Facile and fast preparation of low-cost silica-supported graphitic carbon nitride for solid-phase extraction of fluoroquinolone drugs from environmental waters.

The analytical application of silica-supported graphitic carbon nitride (g-C3N4@silica) for solid-phase extraction (SPE) of fluoroquinolone (FQ) pollutants from water is presented for the first time. g-C3N4@silica was easily and quickly prepared by one-pot thermal condensation of dicyandiamide and characterized by powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared spectroscopy and surface area measurements. The novel composite was applied as sorbent for SPE of FQs from water prior high-performance liquid chromatography with fluorescence detection. The extraction efficiency of g-C3N4 was tested in tap and surface waters at actual concentrations (10-100ngL-1). Quantitative adsorption was achieved using 100mg sorbent (20wt% g-C3N4) for pre-concentration of 50-500mL sample, at the native pH (∼7.5-8). Elution was performed with 25mM H3PO4 aqueous solution-acetonitrile (80:20), obtaining recoveries in the range 70-114%, enrichment factors up to 500 and inter-day RSDs≤12%. The batch-to-batch reproducibility was assessed on three independently synthesized g-C3N4@silica preparations (RSD 6-12%). g-C3N4 supported on silica microparticles proved to be of easy preparation, inexpensive, reusable for at least 4 extractions of raw surface waters, and suitable for determination in real matrices.