Guillermina Font

Solid-phase extraction in multi-residue pesticide analysis of water

The determination of pesticides in water is fundamental to the solution of environmental problems as natural waters are usually contaminated with a large number of pesticides. The selection of an isolation and/or concentration technique depends largely on the class of pesticides to be determined. It is often necessary to determine simultaneously a wide variety of compounds in a water sample. Application of solid-phase extraction techniques offers a solution. The mechanisms of solid-phase extraction, types of sorbents and their application to multi-residue pesticide analysis are reviewed.

Comparison of microextraction procedures to determine pesticides in oranges by liquid chromatography-mass spectrometry.

A liquid chromatographic-mass spectrometric method has been developed for the determination of bitertanol, carbendazim, fenthion, flusilazole, hexythiazox, imidacloprid, methidathion, methiocarb, pyriproxyfen and trichlorfon. Two procedures, based on stir bar sorptive extraction (SBSE) and matrix solid-phase dispersion (MSPD), have been evaluated for the extraction of these compounds in oranges. Their respective advantages and disadvantages are also discussed. The recoveries obtained by MSPD ranged from 47 to 96% and the relative standard deviations (RSDs) ranged from 1 to 15%, whereas with the SBSE method the recoveries were between 8 and 84% and the RSDs between 4 and 16%. Although, the limits of quantitation of most compounds are much better (0.001-0.05 mg kg(-1)) by SBSE, it is not suitable to determine some polar pesticides as carbendazim, imidacloprid and trichlorfon. Results obtained by both methods were compared, in terms of sensitivity and selectivity, with a classical ethyl acetate extraction method, and the three methods were applied to analyze real samples. As MSPD is easier to perform, faster than the organic solvent extraction, and shows equal accuracy and resolution, its application for analyzing pesticides in oranges is recommended.

Pesticide residue determination in fruit and vegetables by liquid chromatography-mass spectrometry

An overview is given of pesticide residue determination in fruit and vegetables by liquid chromatography-mass spectrometry (LC-MS). Emphasis is placed on the thermospray, particle beam and atmospheric pressure ionization interfaces including advantages and drawbacks and typical detection limits. The capacity of each interface to provide useful data for identification/confirmation of analytes and the possibility of obtaining structural information for the identification of target and non-target compounds is discussed. Finally, sample preparation techniques are dealt with in relation to their influence on further LC-MS determination.

In vivo toxicity studies of fusarium mycotoxins in the last decade: A review

This review summarizes the information regarding the in vivo studies of Fusarium mycotoxins in the last decade. The most common studies are classified as subacute toxicity, subchronic toxicity, acute toxicity, toxicokinetic studies and teratogenicity in order of importance. The most used animals in in vivo studies are pigs, rats, chickens and mice. Fumonisin B1, deoxynivalenol, zearalenone, nivalenol and T-2 toxin are the most studied fusarotoxins. Studies with combinations of mycotoxins are also frequent, deoxynivalenol generally being one of them. The predominant route of administration is oral, administered mostly in the form of naturally contaminated feed. Other administration routes also used are intraperitoneal, intravenous and subcutaneous. In vivo research on Fusarium mycotoxins has increased since 2010 highlighting the need for such studies in the field of food and feed safety.

Reactive oxygen species induced by beauvericin, patulin and zearalenone in CHO-K1 cells.

The cytotoxic effects of mycotoxins, induction of reactive oxygen species (ROS) and generation of lipid peroxidation products in CHO-K1 cells were determined as function of increasing time of exposure and concentrations of beauvericin (BEA), patulin (PAT) and zearalenone (ZEA). The end points were evaluated after 24h of exposure, by the tetrazolium salt (MTT) and neutral red (NR) assays. The IC(50) values obtained on the MTT and NR assays ranged from 0.69 to 79.40 microM and 4.40 to 108.76 microM, respectively. To determine the intracellular production of ROS, the intensity of fluorescence emitted from the probe H(2)-DCFDA was measured. The relative intensity of fluorescence from cells incubated with BEA, PAT and ZEA was approximately 4-, 7- and 4-fold higher in comparison with control cells at 0 min, respectively. Lipid peroxidation induced by ROS generation was assessed using the thiobarbituric acid reactive substances (TBARS) method for 2, 24 and 48 h. The malondialdehyde (MDA) production was increased with BEA and PAT exposure in a concentration- and time-dependent manner. MDA was not increased after 1 and 5 microM ZEA exposures for 2h, but was slightly increased at 50 microM. In conclusion, PAT was the most cytotoxic mycotoxin to CHO-K1 cells, followed by BEA and ZEA. Mycotoxins reduce cell viability correlated with the increases of ROS generation and MDA formation in concentration- and time-dependent manner. These data suggested that cytotoxicity and ROS generation are mechanisms of mycotoxins mediated toxicity.

Further data on the presence of Fusarium emerging mycotoxins enniatins, fusaproliferin and beauvericin in cereals available on the Spanish markets

In this work, 64 samples of cereals purchased from local markets in the Valencian community (Spain) were investigated for the presence of six emerging mycotoxins: enniatins ENs (ENA, ENA1, ENB and ENB1), beauvericin (BEA) and fusaproliferin (FUS). Samples were extracted with a mixture of water/acetonitrile (85/15, v/v) by using an Ultra-turrax homogenizer. Mycotoxins were then identified and quantified with a liquid chromatography (LC) with diode array detector (DAD). Positive samples were confirmed with an LC-MS/MS. Analytical Results showed that the frequencies of contamination of samples with ENs, BEA and FUS were 73.4%, 32.8% and 7.8%, respectively. ENA1 was the most mycotoxin found and levels ranged from 33.38 to 814.42 mg/kg. ENB levels ranged between 2.23 and 21.37 mg/kg. ENB1 levels varied from 4.34 to 45.94 mg/kg. All samples were free of ENA. BEA levels ranged from 0.51 to 11.78 mg/kg and FUS levels varied between 1.01 and 6.63 mg/kg. It could be concluded from this study that the high contamination levels found especially for ENs could be of a negative impact on the population. This is the first paper on the presence of emerging mycotoxins in cereals available in Spain.

Determination of triazines and organophosphorus pesticides in water samples using solid-phase extraction

Octadecyl (C18)-bonded porous silica was evaluated for the extraction of triazine and organophosphorus pesticides from natural water. The extraction results showed an effective performance when 11 of water was passed through small glass columns containing 500 mg of 50-100-microns C18 bonded porous silica. The adsorbed compounds were removed with ethyl acetate, evaporated to 200 microliters and determined by gas chromatography. The overall average recoveries were greater than 85% except for dimethoate and trichlorfon. Application of this procedure to the analysis of natural water samples gave results that agree well with those obtained by solvent extraction methods.

Determination of fungicide residues in fruits and vegetables by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

A liquid chromatography (LC) method for the quantitative determination of five fungicide residues (dichloran, flutriafol, o-phenylphenol, prochloraz and tolclofos methyl) in oranges, lemons, bananas, peppers, chards and onions is described. The residues were extracted by matrix solid-phase dispersion (MSPD) using C8. Quantitative analysis was performed by isocratic LC coupled to quadrupole mass spectrometer using atmospheric pressure chemical ionization in the negative ionization mode. The limit of quantification was 0.01 mg kgmicro for flutriafol, o-phenylphenol and dichloran, and 0.1 mg kg(-1) for prochloraz and tolclofos methyl. The MSPD method is also suitable for LC-UV analysis but higher limits of quantification (between 1 and 5 mg kg(-1)) were obtained. Validation of the method was performed between 0.01 and 25 mg kg(-1). Recoveries for fungicides ranged from 52.5 to 91.1% with relative standard deviations between 6.1 and 11.9%. The method was applied to the determination of residues in samples taken from agricultural cooperatives. The fungicides most often detected were o-phenylphenol and prochloraz.

Matrix effects on solid-phase microextraction of organophosphorus pesticides from water

Abstract This study develops a method for solid-phase microextraction (SPME) of eight organophosphorus pesticides, diazinon, fenthion, fenitrothion (sumithion), methyl-parathion, parathion, methyl-trithion, ethion and triazophos, from water. Determination is carried out by gas chromatography with nitrogen-phosphorus detection. To perform the SPME, poly(dimethylsiloxane) and polyacrylate fibers were initially compared on the basis of their absorption capacities for the selected pesticides, and polyacrylate was selected to accomplish the rest of assays. The main factors affecting the SPME process such as memory effect, stirring rate, extraction temperature and absorption-time profile were studied. The proposed method requires 2 ml of sample and reaches limits of detection ranging between 6 ng/l for fenthion and 136 ng/l for methyl-parathion, with relative standard deviations at the 500 ng/l level between 2% for diazinon and 13% for ethion. The method was applied to spiked tapwater, seawater, wastewater with high dissolved organic matter content (DOC = 212 mg/l) and water containing 15 mg/l of sodium lauryl sulfate (SDS), which were previously analyzed to control interferences. Recoveries for diazinon, fenthion and methyl-trithion were better from seawater than from Milli-Q water. Recoveries for fenthion and ethion increased with the presence of SDS and those for methyl-parathion and triazophos decreased from the wastewater because of the presence of the organic matter. Finally, a wastewater from a pesticide producer industry was analyzed showing the presence of diazinon and ethion at concentrations of 0.97 μg/l and 0.67 μg/l, respectively. Results were in concordance with those obtained using a standard liquid-liquid extraction method.

Determination of macrolide antibiotics in meat and fish using pressurized liquid extraction and liquid chromatography–mass spectrometry ☆

We developed a method for determining the quantities of seven macrolide antibiotics in meat and fish by using pressurized liquid extraction (PLE) and liquid chromatography-mass spectrometry with electrospray ionization (LC-(ESI)MS). The PLE was optimized with regard to solvents, temperature, pressure, extraction time and number of cycles. The optimum conditions were: methanol as the extraction solvent; a temperature of 80 degrees C; a pressure of 1500psi; an extraction time of 15min; 2 cycles; a flush volume of 150% and a purge time of 300s. All recoveries for macrolide antibiotics were over 77% at 200mug/kg, except for erythromycin, which was 58%. The repeatability and reproducibility on days in between, expressed as %RSD (n=12), were lower than 10% and 12%, respectively. The quantification limits of all compounds were 25mug/kg of dry weight of animal muscle except for troleandomycin (50mug/kg). The method was applied to determine the pharmaceuticals in real samples taken from 18 meat and fish samples. The results showed that PLE is quantitative short time consuming technique, with use of smaller initial sample sizes. Greater specificity and selectivity in extraction and increased potential for automation were shown.