Solid-phase microextraction and gas chromatography-mass spectrometry for the rapid screening of triazole residues in wine and strawberries

High contamination of a sentinel vertebrate species by azoles in vineyards: a study of common blackbirds (Turdus merula) in multiple habitats in western France

Azoles represent the most used family of organic fungicides worldwide and they are used in agriculture to circumvent the detrimental impact of fungi on yields. Although it is known that these triazoles can contaminate the air, the soil, and the water, field data are currently and dramatically lacking to assess if, and to what extent, the use of triazoles could contaminate non-target wild vertebrate species, notably in agroecosystems. In this study, we aimed to document for the first time the degree of blood contamination of a generalist wild bird species by multiple azoles which are used for plant protection and fungi pest control in various habitats. We deployed passive air samplers and captured 118 Common blackbirds (Turdus merula) in an agroecosystem (vineyard), a protected forest, and a city in western France. We collected blood and analyzed the plasma levels of 13 triazoles and 2 imidazoles. We found that a significant percentage of blackbirds living in vineyards have extremely high plasma levels of multiple azoles (means (pg.g^-1); tebuconazole: 149.23, difenoconazole: 44.27, fenbuconazole: 239.38, tetraconazole: 1194.16), while contamination was very limited in the blackbirds from the protected forest and absent in urban blackbirds. Interestingly, we also report that the contamination of blackbirds living in vineyard was especially high at the end of Spring and the beginning of Summer and this matches perfectly with the results from the passive air samplers (i.e., high levels of azoles in the air of vineyards during June and July). However, we did not find any correlation between the levels of plasma contamination by azoles and two simple integrative biomarkers of health (feather density and body condition) in this sentinel species. Future experimental studies are now needed to assess the potential sub-lethal effects of such levels of contamination on the physiology of non-target vertebrate species.

Facile synthesis of magnetic zinc metal-organic framework for extraction of nitrogen-containing heterocyclic fungicides from lettuce vegetable samples

We present a simple method for the fabrication of a magnetic amino-functionalized zinc metal-organic framework based on a magnetic graphene oxide composite. The resultant framework exhibited a porous 3D structure, high surface area and good adsorption properties for nitrogen-containing heterocyclic fungicides. The adsorption process and capacity indicated that the primary adsorption mechanism might be hydrogen bonding and π-π conjugation. In addition, an optimized protocol for magnetic solid phase extraction was developed (such as adsorbent content, pH, and desorption solvent), and utilized for the extraction of nitrogen-containing heterocyclic fungicides from vegetable samples. Quantitation by high performance liquid chromatography coupled with tandem mass spectrometry offered a detection limit of 0.21-1.0 μg/L (S/N = 3) with correlation coefficients larger than 0.9975. These results demonstrate that magnetic amino-functionalized zinc metal-organic framewor is a promising adsorbent for the extraction and quantitation of nitrogen-containing heterocyclic fungicides.

Covalent Bonding of Metal-Organic Framework-5/Graphene Oxide Hybrid Composite to Stainless Steel Fiber for Solid-Phase Microextraction of Triazole Fungicides from Fruit and Vegetable Samples

A hybrid material of the zinc-based metal-organic framework-5 and graphene oxide (metal-organic framework-5/graphene oxide) was prepared as a novel fiber coating material for solid-phase microextraction (SPME). The SPME fibers were fabricated by covalent bonding via chemical cross-linking between the coating material metal-organic framework-5/graphene oxide and stainless steel wire. The prepared fiber was used for the extraction of five triazole fungicides from fruit and vegetable samples. Gas chromatography coupled with microelectron capture detector (GC-μECD) was used for quantification. The developed method gave a low limit of detection (0.05-1.58 ng g(-1)) and good linearity (0.17-100 ng g(-1)) for the determination of the triazole fungicides in fruit and vegetable samples. The relative standard deviations (RSDs) for five replicate extractions of the triazole fungicides ranged from 3.7 to 8.9%. The method recoveries for spiked fungicides (5, 20, and 50 ng g(-1)) in grape, apple, cucumber, celery cabbage, pear, cabbage, and tomato samples were in the range of 85.6-105.8% with the RSDs ranging from 3.6 to 11.4%, respectively, depending on both the analytes and samples. The metal-organic framework-5/graphene oxide coated fiber was stable enough for 120 extraction cycles without a significant loss of extraction efficiency. The method was suitable for the determination of triazole fungicides in fruit and vegetable samples.

Detection of triazole pesticides in environmental water and juice samples using dispersive liquid–liquid microextraction with solidified sedimentary ionic liquids

The solidification of a sedimentary ionic liquid, [P₄₄₄₈][PF₆], was used to simplify the extraction process for the detection of triazole pesticides.

Genotoxic effects of commercial formulations of Chlorpyrifos and Tebuconazole on green algae

The alkaline single-cell gel electrophoresis assay (comet assay) was used for the study of the genotoxic effects of insecticide Chlorpyrifos and fungicide Tebuconazole (commercial formulations) on two freshwater green algae species, Pseudokirchneriella subcapitata and Nannocloris oculata, after 24 h of exposure. The percentage of DNA in tail of migrating nucleoids was taken as an endpoint of DNA impairment. Cell viability was measured by fluorometric detection of chlorophyll "a" in vivo and the determination of cell auto-fluorescence. Only the higher concentration of Chlorpyrifos tested resulted to affect significantly the cell viability of P. subcapitata, whereas cells of N. oculata were not affected. Tebuconazole assayed concentrations (3 and 6 mg/l) did not affect cell viability of both species. The results of comet assay on P. subcapitata showed that Chlorpyrifos concentration evaluated (0.8 mg/l) exerted a genotoxic effects; while for the other specie a concentration of 10 mg/l was needed. Tebuconazole was genotoxic at 3 and 6 mg/l for both species. The comet assay evidenced damage at the level of DNA simple strains molecule at pesticide concentrations were cytotoxicity was not evident, demonstrating that algae are models to take into account in ecological risk assessments for aquatic environments.

Proteomic analysis of complex protein samples by MALDI-TOF mass spectrometry

MALDI MS has become a technique of considerable impact on many fields, from proteomics to lipidomics, including polymer analysis and, more recently, even low molecular weight analytes due to the introduction of matrix-less ionization techniques (e.g., DIOS) or new matrices such as ionic liquids, proton sponges, and metal nanoparticles. However, protein identification by peptide mass fingerprint (PMF) still remains the main routine application. In the last few years, MALDI MS has played an emerging role in food chemistry especially in detection of food adulterations, characterization of food allergens, and investigation of protein structural modifications, induced by various industrial processes that could be detrimental for food quality and safety. Sample handling and pretreatment can be very different depending on the physical state, liquid or solid, of the analyzed matrices. Here, we describe simple protocols for protein extraction and MALDI MS analysis of liquid (milk) and solid (hazelnuts) samples taken as model. A classic approach based on a preliminary SDS gel electrophoresis separation followed by in-gel digestion and a faster approach based on in-solution digestion of whole samples are described and compared.

Dispersive liquid-liquid microextraction combined with online preconcentration MEKC for the determination of some phenoxyacetic acids in drinking water

A fast and simple technique composed of dispersive liquid-liquid microextraction (DLLME) and online preconcentration MEKC with diode array detection was developed for the determination of four phenoxyacetic acids, 2,4,5-trichlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, 2,6-dichlorophenoxyacetic acid, and 4-chlorophenoxyacetic acid, in drinking water. The four phenoxyacetic acids were separated in reversed-migration MEKC to the baseline. About 145-fold increases in detection sensitivity were observed with online concentration strategy, compared with standard hydrodynamic injection (5 s at 25 mbar pressure). LODs ranged from 0.002 to 0.005 mg/L using only the online preconcentration procedures without any offline concentration of the extract. A DLLME procedure was used in combination with the proposed online preconcentration strategies, which achieved the determination of analytes at limits of quantification ranging from 0.2 to 0.5 μg/kg, which is far lower than the maximum residue limits established by China. The satisfactory recoveries obtained by DLMME spiked at two levels ranged from 67.2 to 99.4% with RSD <15%, making this proposed method suitable for the determination of phenoxyacetic acids in water samples.

Generic sample treatment method for simultaneous determination of multiclass pesticides and mycotoxins in wines by liquid chromatography-mass spectrometry

In this work, a generic sample treatment method for simultaneous determination of multiclass pesticides and mycotoxins in wines is presented. The proposed method is based on solid-phase extraction (SPE) using polymeric-type SPE cartridges. To evaluate the proposed sample treatment, a liquid chromatography electrospray time-of-flight mass spectrometry method was used for testing 60 selected representative multiclass pesticides and 9 mycotoxins. Two different polymeric sorbents were evaluated, with hydrophilic-lipophilic-balanced (HLB) polymer cartridges being selected (Oasis HLB) as the most suitable for the present study. The identification and confirmation of the compounds was based on retention time and accurate mass measurements of the protonated molecules ([M+H](+)). Limits of detection were below 1 μg L(-1) for the 87% of the studied compounds. With the selected 4:1 preconcentration factor, 70% of the target compounds showed relatively low matrix effects, corresponding to signal suppressions lower than 30%. Recovery studies (n=10) were carried out at two concentration levels, 2.5 μg L(-1) and 25 μg L(-1), obtaining mean recovery rates between 70 and 120% for the 90% of studied analytes. The relative standard deviation (RSD%) values of the entire procedure were below 15% in most cases (97% of the studied analytes). The proposed method was successfully applied to 24 red wine samples produced in different regions of Spain. The concentration levels of the target compounds found in the studied samples were in compliance with the current regulations. Aflatoxin B(2) and metalaxyl were the most detected compounds (75% and 50% of the studied samples, respectively).

Persistence of trifloxystrobin and tebuconazole on grape leaves, grape berries and soil

Following four foliar applications of Nativo 75 WG (trifloxystrobin 25% + tebuconazole 50%) on grapes @ 175 and 350 g/ha, resulting in active applications of trifloxystrobin @ 43.75 and 87.5 g a.i./ha and that of tebuconazole @ 87.5 and 175 g a.i./ha, the average initial deposits of trifloxystrobin were observed to be 7.76 and 15.53 mg/kg, respectively, at single and double the application rates. These residue levels dissipated to >85% after 10 days of its application at both the dosages. Similarly, the average initial deposits of tebuconazole were observed to be 13.84 and 26.55 mg/kg at single and double the application rate, respectively. These residue levels dissipated to >90% after 10 days of application at both the dosages. The half-life (t(1/2)) periods of trifloxystrobin on grape leaves were observed to be 2.92 and 3.48 days at single and double application rates, respectively, whereas these values were 2.68 and 3.96 days for tebuconazole. Ripe grape berries and soil samples collected at harvest which happened to be 34 days after the last application, did not show the presence of residues of trifloxystrobin and tebuconazole at their determination limit of 0.01 and 0.02 mg/kg, respectively.

Development of monoclonal immunoassays for the determination of triazole fungicides in fruit juices

Enzyme-linked immunosorbent assays (ELISAs) based on monoclonal antibodies for the detection of triazole fungicides have been developed. With this aim, hapten-protein conjugates, containing the common triazole and chlorinated aromatic moieties, were prepared. From mice immunized with these conjugates, several monoclonal antibodies (MAbs) with the ability to sensitively bind several triazoles with different specificity were obtained. Both analyte- and class-specific ELISAs were developed. The hexaconazole-specific immunoassay can determine this fungicide with a limit of detection of 0.3 mug/L in standard buffer. The so-called triazole-specific immunoassay allowed for the detection of tetraconazole, penconazole, cyproconazole, and myclobutanil, with limits of detection in the 0.1-0.7 mug/L range. These immunoassays were applied to the determination of triazoles in spiked fruit juices. Samples were adequately diluted to minimize the matrix effects. Coefficients of variation were below 30%, and recoveries ranged from 62 to 135%. Therefore, the developed immunoassays can determine triazole fungicides in fruit juices down to the maximum residue limits currently legislated, without any sample treatment other than dilution.

Gas chromatographic method for the determination of hexaconazole residues in black tea

A highly reliable, quantitative and sensitive analytical method for determining the residues of the fungicide, hexaconazole in black tea is described. The proposed method is based on liquid-liquid extraction followed by gas chromatographic determination, using nitrogen phosphorus detector (GC-NPD) for the identification and quantitation of hexaconazole. The most appropriate solvent mixture for extracting hexaconazole residues from black tea was n-hexane:acetone at 1:1 (v/v). The extract was cleaned up by adsorption column chromatography using activated florisil. Performance of the method was assessed by evaluating quality parameters such as recovery value, repeatability, reproducibility, linearity and limits of detection and quantitation. When the method was assessed for repeatability, the percentage of recovery ranged between 86% and 96% while the relative standard deviation was between 0.30% and 2.35%. In studies on reproducibility the recovery ranged from 81% to 85% and relative standard deviation from 1.68% to 5.13%, implying that the method was reliable. A field trial was conducted to verify the application of this method with real samples. Results prove that the validated method was suitable for extracting hexaconazole residues.

Development and application of quantitative methods for monitoring dermal and inhalation exposure to propiconazole

Quantitative methods to measure dermal and inhalation exposure to the fungicide propiconazole were developed in the laboratory and applied in the occupational exposure setting for monitoring five farm workers' exposure during pesticide preparation and application to peach crops. Dermal exposure was measured with tape-strips applied to the skin, and the amount of propiconazole was normalized to keratin content in the tape-strip. Inhalation exposure was measured with an OVS tube placed in the worker's breathing-zone during pesticide handling. Samples were analyzed by GC-MS in EI+ mode (limit of detection 6 pg microl(-1)). Dermal exposure ranged from non-detectable to 32.1 +/- 22.6 ng per microg keratin while breathing-zone concentrations varied from 0.2 to 2.2 microg m(-3). A positive correlation was observed between breathing-zone concentrations and ambient air temperature (r2 = 0.87, p < 0.01). Breathing-zone concentrations did not correlate with dermal exposure levels (r2 = 0.11, p = 0.52). Propiconazole levels were below limit of detection when rubber gloves, coveralls, and full-face mask were used. The total-body propiconazole dose, determined for each worker by summing the estimated dermal dose and inhalation dose, ranged from 0.01 to 12 microg per kg body weight per day. Our results show that tape-stripping of the skin and the OVS can be effectively utilized to measure dermal and inhalation exposure to propiconazole, respectively, and that the dermal route of exposure contributed substantially more to the total dose than the inhalation route.

Methods of sample preparation for determination of pesticide residues in food matrices by chromatography-mass spectrometry-based techniques: a review

Much progress has been made in pesticide analysis over the past decade, during which time hyphenated techniques involving highly efficient separation and sensitive detection have become the techniques of choice. Among these, methods based on chromatographic separation with mass spectrometric detection have resulted in greater likelihood of identification and are acknowledged to be extremely useful and authoritative methods for determination of pesticide residues. Even with such powerful instrumental techniques, however, the risk of interference increases with the complexity of the matrix studied, so sample preparation before instrumental analysis is still mandatory in many applications, for example food analysis. This article summarizes the analytical characteristics of the different methods of sample-preparation for determination of pesticide residues in a variety of food matrices, and surveys their recent applications in combination with chromatographic mass spectrometric analysis. We discuss the advantages and the disadvantages of the different methods, address instrumental aspects, and summarize conclusions and perspectives for the future.

Determination of imidazole and triazole fungicide residues in honeybees using gas chromatography–mass spectrometry

An analytical method employing clean up by high-performance gel permeation chromatography (HPGPC) and solid-phase extraction (SPE) on Florisil cartridges was developed to determine residues of eleven imidazole and triazole ergosterol-biosynthesis-inhibiting (EBI) fungicides in honeybee samples. Detection was by means of gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. The method was validated by fortifying control samples at levels of 0.01 and 0.05 micro g/bee. Mean recoveries for each analyte except imazalil were between 79 and 99% with relative standard deviations of 12.3% or less. Mean recoveries of imazalil were 51% at 0.01 micro g/bee and 81% at 0.05 micro g/bee. Limits of detection for the analytes investigated ranged from 0.005 to 0.001 micro g/bee.

Mass spectrometry in grape and wine chemistry. Part II: The consumer protection

Controls in food industry are fundamental to protect the consumer health. For products of high quality, warranty of origin and identity is required and analytical control is very important to prevent frauds. In this article, the "state of art" of mass spectrometry in enological chemistry as a consumer safety contribute is reported. Gas chromatography-mass spectrometry (GC/MS) and liquid-chromatography-mass spectrometry (LC/MS) methods have been developed to determine pesticides, ethyl carbamate, and compounds from the yeast and bacterial metabolism in wine. The presence of pesticides in wine is mainly linked to the use of dicarboxyimide fungicides on vineyard shortly before the harvest to prevent the Botrytis cinerea attack of grape. Pesticide residues are regulated at maximum residue limits in grape of low ppm levels, but significantly lower levels in wine have to be detected, and mass spectrometry offers effective and sensitive methods. Moreover, mass spectrometry represent an advantageous alternative to the radioactive-source-containing electron capture detector commonly used in GC analysis of pesticides. Analysis of ochratoxin A (OTA) in wine by LC/MS and multiple mass spectrometry (MS/MS) permits to confirm the toxin presence without the use of expensive immunoaffinity columns, or time and solvent consuming sample derivatization procedures. Inductively coupled plasma-mass spectrometry (ICP/MS) is used to control heavy metals contamination in wine, and to verify the wine origin and authenticity. Isotopic ratio-mass spectrometry (IRMS) is applied to reveal wine watering and sugar additions, and to determine the product origin and traceability.

Quantitation of 13 azole fungicides in wine samples by liquid chromatography–tandem mass spectrometry

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed for the direct quantitation of residues of 13 azole fungicides in wine and has been successfully applied to 103 wine samples. The method utilizing 25 transitions is highly sensitive and specific with centrifugation as the only sample work-up step. Precision was better than 14% and accuracy ranged between 80 and 120%. Quantitation limits (LOQs) ranged between 0.25 (penconazole) and 7.5 ng/mL (triadimefon). Since the LOQs achieved are at least four times lower than the maximum residue levels for azole-fungicides in wine prescribed, the method presented here can be conveniently used as a screening assay for azole-residues in wine samples.

Determination of azolic fungicides in wine by solid-phase extraction and high-performance liquid chromatography–atmospheric pressure chemical ionization–mass spectrometry

A method for simultaneous analysis of eight azolic fungicides: cyproconazole, diniconazole, tetraconazole, thiabendazole, flusilazole, triadimenol, triadimefon, carbendazim and the degradation product 2-aminobenzimidazole in wine samples is described. The compounds are isolated from the samples and concentrated by solid-phase extraction on polymeric cartridges. The determination is carried out by liquid chromatography with mass spectrometric detection in positive ionization and selected ion monitoring modes. The influence of parameters such as the mobile phase composition, column temperature, corona current and fragmentor voltage is studied and the proposed method is validated. Recoveries of the nine compounds added to wine samples range from 83 to 109%, with relative standard deviations below 10%. The quantitation limits are between 9 and 31 microg/L. Real wine samples are analyzed by the proposed method, also.

Determination of major compounds in sweet wines by headspace solid-phase microextraction and gas chromatography

Headspace solid-phase microextraction (HS-SPME) was studied by high resolution gas chromatographic analysis of major compounds (ethyl acetate, methanol, 1-butanol, 2-butanol, 1-propanol, isobutanol, 2-methyl-1-butanol and 3-methyl-1-butanol) in sweet wines. Five different SPME fibres were tested and the influence of different factors such as temperature and time of desorption, extraction time, stirring, sample and vial volume, sugar and ethanol content were studied and optimized using model solutions. The SPME method was validated with the direct injection method. The proposed HS-SPME-GC method is an appropriate technique for the quantitative analysis of the mentioned analytes in real sweet wines.