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 C-8. 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/kg for flutiiafol, o-phenylphenol and dichloran, and 0.1 mg/kg 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) were obtained. Validation of the method was performed between 0.01 and 25 mg/kg. 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.