Effect of clarification process on the removal of pesticide residues in red wine and comparison with white wine.

The aim of this study was to determine the potential of seven clarifying agents to remove pesticides in red wine. The presence of pesticides in wine consists a great problem for winemakers and therefore, results on pesticide removal by clarification are very useful for taking a decision on the appropriate adsorbent. The selection of an efficient adsorbent can be based on data correlating pesticide removal in red wine to pesticides' properties, given the great number and variety of pesticides used. So, this experimental work is focused on the collection of results with regard to pesticide removal by clarification using a great number of pesticides and fining agents. A Greek red wine, fortified with single solutions and mixtures of 23 or 9 pesticides was studied. The seven fining agents, used at two concentrations, were activated carbon, bentonite, polyvinylpolypyrrolidone (PVPP), gelatin, egg albumin, isinglass-fish glue, and casein. Pesticides were selected with a wide range of properties (octanol-water partition coefficient (log Kow) 2.7-6.3 and water solubility 0.0002-142) and belong to 11 chemical groups. Solid phase extraction (SPE) followed by gas chromatography (GC) with electron capture detector (ECD) were performed to analyze pesticide residues of the clarified fortified wine. The correlation of the clarifying agents' effectiveness to pesticide's chemical structure and properties (log Kow, water solubility) was investigated. The antagonistic and/or synergistic effects, occurring among the pesticides in the mixtures, were calculated by indices. Pesticide removal effectiveness results of the red wine were compared to those obtained from a white wine under the same experimental conditions and discussed. The order of decreasing adsorbent effectiveness (mixture of 23 pesticides) was: activated carbon 40% > gelatin 23% > egg albumin 21% > PVPP 18% > casein 12% > bentonite 7%. Isinglass showed 12% removal at the highest permitted concentration. In the case of 9 pesticides mixture, the effectiveness was quite higher but the order remained the same compared to 23 pesticides mixture. The removal of each pesticide from its single solution was generally the highest (particularly for hydrophobic pesticides). Adsorption on fining agents is increased by increasing hydrophobicity and decreasing hydrophilicity of organic pesticide molecules.

Fipronil in eggs. Is LC-MS/MS the only option? A comparison study of LC-MS/MS and GC-ECD for the analysis of fipronil.

Fipronil is a broad-spectrum insecticide belonging to the phenylpyrazole chemical family, classified by the U.S. EPA as a group C (possible human) carcinogen. It is highly toxic to crustaceans, insects and zooplankton as well as to termites, rabbits and certain groups of gallinaceous birds. In European Union and Greece, fipronil is authorized only for the control of termites and cockroaches and not as a plant protection product or as a veterinary drug. The definition of residue of fipronil comprises of the sum of fipronil and its sulfone metabolite expressed as fipronil and is set at 5 µg kg-1. In this study, a sensitive and reliable modified QuEChERS method, proposed by the European Reference Laboratory for animal origin products, has been validated and applied to the residue analysis of fipronil and its metabolites (sulfone and desulfinyl) in chicken eggs and other egg products by LC-MS/MS and GC-ECD analysis. The two analytical systems performed almost equally concerning validation process and with regard to the analysis of real samples, results from both systems were in agreement: out of 11 samples analysed, 4 samples showed measurable residues of fipronil sulfone with 3 samples exceeding the MRL limit.

Determination of benzoylurea insecticide residues in tomatoes by high-performance liquid chromatography with ultraviolet-diode array and atmospheric pressure chemical ionization-mass spectrometry detection.

A simple and sensitive method using high-performance liquid chromatography/ mass spectrometry (LC/MS) was developed and validated for simultaneous determination of 5 benzoylurea insecticides-diflubenzuron, triflumuron, teflubenzuron, lufenuron, and flufenoxuron-in tomatoes. Residues were successfully separated on a C18 column by methanol-water isocratic elution. Detection was carried out by an ultraviolet diode array detector (UV-DAD) coupled with a quadrupole mass spectrometer, using atmospheric pressure chemical ionization (APCI) in negative-ion mode. The main ions were the deprotonated molecules [M-H]- for triflumuron, and the anions formed by elimination of hydrofluoric acid [M-H-HF]- for diflubenzuron and flufenoxuron, and [M-2H-HF] for lufenuron and teflubenzuron. The calibration plots were linear for both detectors over the range 0.05 to 10 microg/mL, and the method presented good quality parameters. The limits of detection for standard solutions were 0.008-0.01 mg/L (equivalent to 0.08-0.1 ng injected) for both detectors, and the limits of quantification (LOQs) were approximately 10 times lower than national maximum residue levels (MRLs). Depending on the compound and the detector, the LOQ values ranged from 0.2 to 0.4 ng injected. The optimum LC-UV-DAD/APCI-MS conditions were applied to the analysis of benzoylureas in tomatoes. The obtained recoveries from fortified tomato samples (50 g), extracted with ethyl acetate and purified by solid-phase extraction on silica sorbent, were 88-100 and 92.9-105% for the UV-DAD and MS detectors, respectively, with precision values (relative standard deviations) of 2.9-11 and 3.7-14%, respectively. The method was applied to 12 tomato samples from local markets, and diflubenzuron and lufenuron were detected in only one sample at concentrations lower than the MRLs. The results indicate that the developed LC/MS method is accurate, precise, and sensitive for quantitative and qualitative analysis at low levels of benzoylureas required by legislation.

Removal of pesticides from white and red wines by microfiltration.

The aim of this work is the investigation of microfiltration in removing pesticides from a white and a red Greek wine. Six membranes with pore size 0.45µm were investigated. Two mixtures of 23 and 9 pesticides, and single pesticide solutions were added in the wine. The pesticides tested belong to 11 chemical groups. Solid phase extraction (SPE) followed by gas chromatography (GC) with electron capture detector (ECD) were performed to analyze pesticide residues of the filtered fortified wine. Distinct behavior was exhibited by each membrane. Cellulose acetate and cellulose nitrate showed higher mean pesticide removal for both wines, followed by polyethersulfone, regenerated cellulose, and polyamides. The filtration effectiveness was correlated to the membrane type and to the pesticide chemical structure and properties (octanol-water partition coefficient, water solubility) and compared for the wines tested. In most cases, the more hydrophobic pesticides (pyrethroids and aldrin) showed higher removal from red wine than white wine. Adsorption on membranes was increased by increasing hydrophobicity and decreasing hydrophilicity of organic pesticide molecule. The removal of each pesticide from its single solution was generally higher than that from its mixtures, allowing the estimation of the antagonistic and synergistic effects of pesticides in the mixtures.

Rapid multi-residue method for the determination of azinphos methyl, bromopropylate, chlorpyrifos, dimethoate, parathion methyl and phosalone in apricots and peaches by using negative chemical ionization ion trap technology.

A rapid, selective and sensitive multi-residue method for the determination of six common pesticides in stone fruit samples is described. The proposed method involves the extraction of the pesticides with the use of acetone solvent followed by liquid-liquid partition with a mixture of dichloromethane and light petroleum (40-60 degrees C) and subsequent determination by a gas chromatographic-mass spectrometry system using ion trap technology in negative ion chemical ionization mode. The average percent recoveries of bromopropylate and phosalone in the concentration range 0.2-2.0 mg/kg were 97.3 +/- 6.7 to 120 +/- 1.0%, while the recoveries of chlorpyrifos and parathion methyl examined in the concentration range 0.02-0.2 mg/kg were 95.5 +/- 7.5 to 145 +/- 3.6%, the recoveries of azinphos methyl in the range 0.05-0.5 mg/kg were 74.8 +/- 29.6 to 96.5 +/- 13% and those of dimethoate in the range 0.1-1.0 mg/kg were 73.1 +/- 5.7 to 92.8 +/- 2.8% for n = 3 for all the above pesticides. The high mean recovery (145%) for chlorpyrifos is attributed to a matrix enhancement effect. The limits of quantitation in apricots were 0.01 mg/kg for chlorpyrifos, 0.02 mg/kg for dimethoate and parathion methyl, 0.05 mg/kg for azinphos methyl and phosalone and 0.1 mg/kg for bromopropylate. The usefulness of tandem mass spectrometry for confirmation purposes was also examined. The method was applied successfully to the determination of the target pesticides in 32 samples of stone fruits (apricots and peaches).