B. Cancho-Grande

Determination of 23 pesticide residues in leafy vegetables using gas chromatography–ion trap mass spectrometry and analyte protectants

A gas chromatographic method was developed for simultaneously determining residues of 12 insecticides (acrinathrin, bifenthrin, carbofuran, cyfluthrin, lambda-cyhalothrin, cypermethrin, chlorfenvinphos, deltamethrin, esfenvalerate, fenamiphos, methiocarb and tau-fluvalinate) and 11 fungicides (cyprodinil, fludioxonil, iprodione, metalaxyl, penconazole, pyrimethanil, procymidone tebuconazole, triadimefon, triadimenol and vinclozolin) in leafy vegetables. Samples were extracted with acetonitrile and cleaned-up with graphitized carbon black/primary secondary amine (GCB/PSA) solid-phase extraction (SPE) cartridges using acetonitrile:toluene (3:1, v/v) as eluent. The eluate was finally evaporated and redissolved with 0.5 mL of acetone containing the internal standards (pentachlorobenzene and fenpropathrin) and three analyte protectants (3-ethoxy-1,2-propanediol, d-sorbitol and l-gulonic acid gamma-lactone). The addition of analyte protectants allows to avoid the matrix-induced response enhancement effect on quantitation process with absolute recoveries ca. 100%. Precision (expressed as relative standard deviation) was lower than 10% for all pesticides and finally, limits of detection were also 10-20 times lower than maxima residue levels (MRLs) established by European Regulation. The proposed method was applied to determine pesticide residues in commercial leafy vegetables (lettuce, Swiss chard and spinach) purchased from markets in Orense (NW Spain). Pesticide residues were detected in 84% of the total samples (63 from 75 samples) and pesticide concentrations were higher than MRL in 18 samples.

Application of single-drop microextraction and comparison with solid-phase microextraction and solid-phase extraction for the determination of α- and β-endosulfan in water samples by gas chromatography-electron-capture detection

Water contamination due to the wide variety of pesticides used in agriculture practices is a global environmental pollution problem. The 98/83 European Directive requires the measurement of pesticides residues at a target concentration of 1.0 microg/l in surface water and 0.1 microg/l in drinking water. In order to reach the level of detection required, efficient extraction techniques are necessary. The application of a new extraction technique: single-drop microextraction (SDME), followed by gas chromatography with electron-capture detection, was assessed for determining alpha-endosulfan and beta-endosulfan in water samples. Experimental parameters which control the performance of SDME, such as selection of microextraction solvent and internal standard, optimization of organic drop volume, effects of sample stirring, temperature and salt addition, and sorption time profiles were studied. Once SDME was optimized, analytical parameters such as linearity, precision, detection and quantitation limits, plus matrix effects were evaluated. The SDME method was compared with solid-phase microextraction and solid-phase extraction with the aim of selecting the most appropriate method for a certain application.

Multiresidue determination of 11 new fungicides in grapes and wines by liquid-liquid extraction/clean-up and programmable temperature vaporization injection with analyte protectants/gas chromatography/ion trap mass spectrometry.

A gas chromatographic ion trap mass spectrometry (GC-ITMS) method was developed for the determination of 11 new generation fungicides (benalaxyl, benalaxyl-M, boscalid, cyazofamid, famoxadone, fenamidone, fluquinconazole, iprovalicarb, pyraclostrobin, trifloxystrobin and zoxamide) in grapes and wines. Samples were extracted with ethyl acetate:hexane (1:1, v/v) and cleaned-up with graphitized carbon black/primary secondary amine (GCB/PSA) solid-phase extraction (SPE) cartridges using acetonitrile:toluene (3:1, v/v) as eluent. The addition of analyte protectants (3-ethoxy-1,2-propanediol, d-sorbitol and l-gulonic acid gamma-lactone) in the final extracts allowed to avoid the matrix-induced response enhancement effect on quantitation process with absolute recoveries ca. 100%. Precision (expressed as relative standard deviation) was lower than 16% for all fungicides. Limits of detection and quantitation were lower than 0.01 mg/kg or mg/L, except for cyazofamid, much smaller in all cases than maximum residue levels (MRLs) established by European Union for grapes and by Switzerland and Italy for wines. The proposed method was applied to determine fungicide residues in three different white grapes for vinification produced in Ribeiro area in Galicia (NW Spain), as well as in their corresponding final wines.

A Review on the Fate of Pesticides during the Processes within the Food-Production Chain

Only the intake of toxicologically-significant amounts can lead to adverse health effects even for a relatively toxic substance. In the case of residues in foods this is based on two major aspects—first, how to determine quantitatively the presence of a pollutant in individual foods and diets, including its fate during the processes within the food production chain; and second, how to determine the consumption patterns of the individual foods containing the relevant pollutants. The techniques used for the evaluation of the fate of pesticides during food processing have been critically reviewed in this paper to determine those areas where improvements are needed or desirable. Options for improvements are being suggested, including, for example, the development of a pan-European food composition database, activities to understand better effects of processing on individual food pesticides, and harmonization of food consumption survey methods with the option of a regular pan-European survey. The ultimate aim is to obtain appropriate estimations for the presence and quantity of a given chemical in a food and in the diet in general. Existing pragmatic approaches are a first crude step to model food pollutant intake. It is recommended to extend, refine, and validate this approach in the near future. This has to result in a cost-effective exposure-assessment system to be used for existing and potential categories of pollutants. This system of knowledge (with information on sensitivities, accuracy, etc.) will guide future data collection.

Relationships between Godello white wine sensory properties and its aromatic fingerprinting obtained by GC-MS.

Godello is a traditional white-grape vine grown widely in the Valdeorras area (Northwest Spain) available information about the sensory and chemical characteristics of which is scant. In this work, exploratory research was conducted with a view to correlate the results of instrumental analyses of the aroma compounds in Godello wine and their sensory perception. Principal Component Analysis (PCA) and Partial Least Squares Regression (PLS) were the multivariate data analysis methods selected. PCA showed the distribution of the Godello wines based on volatile compounds with Odour Activity Values (OAV) higher or near-unity and sensory characteristics, and PLS exposed relationships between sensory descriptors and volatile compounds, in the wines. The compounds that mostly contributed to the flavour of Godello wines were those conferring a fruity (ethyl esters and acetates, accounting 55.1% of total OAV), spicy (fatty acids, 35.3%) or floral aroma (terpenes, 3.1%) based on instrumental analysis. In sensory analysis the descriptors with the highest intensity percent were fruity and floral aromas (floral, apple and citrus), together with herbaceous notes.

Wine Aroma Compounds in Grapes: A Critical Review

Volatile organic compounds are vital to wine quality, determining their aroma and varietal characteristics. Which are present, and in what quantity, depends on the cultivar, the situation and soil of the vineyard, weather, cultivation methods, and wine-making practices. Here, we review the literature on the development of wine aroma compounds in grapes, and how it is affected by the above-named factors. Increasing understanding of these processes at the molecular level will aid vine growers in the optimal selection of harvest dates and other decisions favoring the consistent production of balanced, flavorful berries.

Comparison of solid-phase extraction and solid-phase microextraction for carbofuran in water analyzed by high-performance liquid chromatography–photodiode-array detection

In this study a direct solid-phase microextraction (SPME) procedure has been developed for the determination of carbofuran in water. Experimental parameters such as selection of SPME coating, effect of temperature, effect of salt addition and solvent desorption were studied and optimized. Analytical parameters such as linearity, precision, detection and quantitation limits, and matrix effects for solid-phase extraction (SPE) and SPME methods were evaluated for comparison purposes with the aim of selecting the most appropriate depending on the detection capabilities required. SPE and SPME were followed by high-performance liquid chromatography with diode-array detection, using a 50 x 4.6 mm I.D. guard column and a 150 x 4.6 mm I.D. analytical column, both packed with C18 silica. Both methods can be applied to real samples and give the same results, but SPE allows the detection of lower carbofuran concentrations (0.06 microg/L) as compared to

Aroma profile of Garnacha Tintorera-based sweet wines by chromatographic and sensorial analyses

The aroma profiles obtained of three Garnacha Tintorera-based wines were studied: a base wine, a naturally sweet wine, and a mixture of naturally sweet wine with other sweet wine obtained by fortification with spirits. The aroma fingerprint was traced by GC-MS analysis of volatile compounds and by sensorial analysis of odours and tastes. Within the volatiles compounds, sotolon (73 μg/L) and acetoin (122 μg/L) were the two main compounds found in naturally sweet wine. With regards to the odorant series, those most dominant for Garnacha Tintorera base wine were floral, fruity and spicy. Instead, the most marked odorant series affected by off-vine drying of the grapes were floral, caramelized and vegetal-wood. Finally, odorant series affected by the switch-off of alcoholic fermentation with ethanol 96% (v/v) fit for human consumption followed by oak barrel aging were caramelized and vegetal-wood. A partial least square test (PLS-2) was used to detect correlations between sets of sensory data (those obtained with mouth and nose) with the ultimate aim of improving our current understanding of the flavour of Garnacha Tintorera red wines, both base and sweet. Based on the sensory dataset analysis, the descriptors with the highest weight for separating base and sweet wines from Garnacha Tintorera were sweetness, dried fruit and caramel (for sweet wines) vs. bitterness, astringency and geranium (for base wines).

Evolution of the aromatic profile in Garnacha Tintorera grapes during raisining and comparison with that of the naturally sweet wine obtained

The postharvest dehydration is one of the most important steps in obtaining a high quality naturally sweet wine and it can play an important role in modulating the production and the release of volatile compounds. However, only a few studies have analysed the changes in the free and bound volatile compounds of grapes throughout the process. In this work, GC-MS was applied to determine the aromatic composition of Garnacha Tintorera grapes subjected to off-vine dehydration or raisining at several points during the process. The total water loss in 83 days was about 62% and the sugar concentration rose from 225 to 464 g/L. Within the free volatile compounds, isoamyl alcohols, benzaldehyde and guaiacol registered the largest increase above the concentration effect due to water loss; while within the bound volatile compounds were isoamyl alcohols, ethyl vanillate and benzoic acid. The aromatic profile of the raisins obtained were mainly caramelised, floral, phenolic and burned.

Aroma potential of Brancellao grapes from different cluster positions.

In this study the presence of aroma compounds in grapes of Brancellao (Vitis vinifera L.) was investigated in order to obtain its aroma potential fingerprint. It is well known that differences exist in aromatic compounds amongst grapevine varieties at ripening stages. Within the framework of an increasingly competitive market, the chance of obtaining different wines from vines of the same variety grown at the same vineyard is becoming of increasing importance. This can be done through the managing of the vineyard, but also some wineries have assayed the separation of the tip and shoulder berries of the clusters of a specific variety with this objective. In this work it is evaluated that, in the final stages of maturation, differences exist in the probable alcoholic degree, total acidity of the must, as well as in the aromatic composition of skin and flesh of berries coming from the tips and shoulders of the clusters. Gas chromatography coupled to mass spectrometry (GC-MS) was used to determine the aromatic composition, in the skin and flesh of each sample, either tip or shoulder berries from the clusters. The obtained results showed that there was not variability for the probable alcoholic degree and total acidity between the shoulders and tips, whereas there was variability for their aromatic composition. For the berries from the tips of the clusters most of volatiles were found in the flesh (except aldehydes) and spicy and floral nuances (with the only exception of β-ionone) were in higher proportions. For the berries from the shoulders of the clusters, most of volatiles were found in the skin (monoterpenes, norisoprenoids, aldehydes, and C6 alcohols), where the flesh was slightly richer in aromatic alcohols, volatile phenols and pantolactone; β-ionone and herbaceous nuances were in higher proportions. These results are promising for those wineries that are considering the chance of separating berries from tips and shoulders of the clusters for the elaboration of different quality wines.