Method development and validation for strobilurin fungicides in baby foods by solid-phase microextraction gas chromatography-mass spectrometry

The present study describes anew solvent-free method for the sensitive determination of seven strobilurin fungicides (azoxystrobin, metominostrobin, kresoxim-methyl, trifloxystrobin, picoxystrobin, dimoxystrobin and pyraclostrobin) in baby food samples. Direct immersion solid-phase microextraction (DI-SPME) coupled to gas chromatography with mass spectrometry in the selected ion monitoring mode, GC-MS (SIM), is used. All analyses were performed with 2 g of sample mass, 14 mL of sample extract volume and sample extract buffered at pH 5. Optimal extraction conditions were 60 degrees C for 40 min under continuous stirring using a PDMS-DVB fiber. Desorption was carried out at 240 degrees C for 4 min. The standard additions method is recommended and quantitation limits ranged from 0.01 to 0.4 ng g(-1) at a signal to noise ratio of 10, depending on the compound. Recoveries obtained for spiked samples were satisfactory for all the compounds. The method was validated according to the Commission Decision 2002/657/EC. Different baby foods were analyzed by the proposed method and none of the samples contained residues above the detection limits. (C) 2008 Elsevier B.V. All rights reserved.