Estimation of the validation parameters for a fast analysis of herbicide residues by LC-MS/MS.

Due to strict regulatory requirements for pesticide residue analysis, only the results of residue analysis with acceptable quality should be reported. As a consequence proper validation of the measurement method is required. In this context, accuracy, precision, specificity, limit of determination (LOQ), matrix effect, linearity, uncertainty calculation and ruggedness become increasingly important. This paper reports a description of the validation parameters of a fast method for the determination of five phenoxy acid herbicides (2,4-D, MCPA, MCPP, haloxyfop and fluazifop) in food crops. The recoveries were performed in the concentration range from 0.05 to 0.5 mg kg⁻¹ for apples, pears, carrots and celeriac with five replicates at each level. The mean recoveries ranged from 70% to 95% for all crops. The precision of the method expressed as a relative standard deviation (RSD%) was found to be in the range 3-14%. For all herbicides, the linearity response of the detector was tested by correlation coefficients (r² > 0.99) in the concentration range from 0.05 to 0.5 mg kg⁻¹. The LOQ was determined as the lowest spiked level meeting the requirement of accuracy (70-120%) and precision (RSD% < 20% according to European Union guidelines. The uncertainty and robustness were calculated. On the basis of the results, the method can be considered fast, simple and robust and is suitable to be applied to the analysis of studied herbicides in routine testing laboratories.

Determination of toxaphene residues in fish foodstuff by GC-MS.

A method for the determination of toxaphene residues in fish and fish-based baby foods has been developed. The cleanup of the fatty matrices was performed using an acid treatment on an Extrelut-NT3 and ENVI-Florisil SPE cartridges system, using light petroleum as eluent. Instrumental analysis was carried out by gaschromatography with mass spectrometry detector (GC/MS) in SIM mode. Recoveries from spiked samples were tested at 0.005 and 0.01 mg/kg per single congener and were in the range 82-104% while relative standard deviations (RSDs) were in the range 3.7-10.9%. Nineteen samples of both frozen fish food and fish-based baby foods representative of the Italian market were collected from local dealers and analysed.

Organochlorine pesticides and polychlorinated biphenyls in 12 edible marine organisms from the Adriatic Sea, Italy, Spring 1997.

Edible portions of 12 marine organisms from several areas of the Adriatic Sea, Italy, were collected during Spring 1997 and analysed for 32 organochlorine pesticides residues and 27 polychlorobiphenyl congeners. Only eight organochlorine pesticides - hexachlorobenzene (HCB), hexachlorocyclohexane (HCH) isomers, diphenyl-dichloro-trichloroethane (DDT) group, dieldrin - were determined at levels in the range <0.01-19.88 ng g(-1) wet weight, with 1,1'-dichloro-2,2'-bis(4-chlorophenyl)ethylene (DDE) being the more relevant single organochlorine. The contamination by organochlorine pesticides was comparable in organisms from the North, Centre and South Adriatic. Polychlorinated biphenyls (PCBs) were determined at levels in the range <0.05-14.46 ng g(-1), with CB 101, 118, 138, 153, 180 and 187 being more relevant (penta-, hexa- and hepta-chlorinated congeners). The sum of PCBs congeners determined were in the range 1.18-69.05 ng g(-1). The contamination by PCBs is more relevant in organisms from the North Adriatic Sea owing to the antropic discharge from major rivers such as Po and Adige that flow through highly industrialized and densely populated areas.