Analysis of Fungicides in Fruits and Vegetables by Capillary Electrophoresis-Mass Spectrometry

A method based on solid-phase extraction (SPE) and capillary electrophoresis-mass spectrometry (CE-MS) for determining fungicides in fruits and vegetables is described. The sample, previously chopped and homogenized, is extracted with a methanol-water mixture by sonication, filtrated, and adjusted to an appropriate volume with water. The target compounds are isolated by solid-phase extraction (SPE) on C8, eluted with dichloromethane, evaporated to dryness, and reconstituted in buffer. Fungicide residues present in the sample are preconcentrated by stacking with buffer removal. Separation is achieved by capillary zone electrophoresis (CZE) using a buffer of formic acid-ammonium formate at pH 3.5 with 2% methanol and an untreated 150 cm � 75 � m fused-silica capillary placed in a special external detector adapter (EDA) cartridge. The CE device is coupled to an electrospray interface by a commercial sheath flow adapter, in which the CE eluate is mixed with a suitable sheath liquid at the probe tip and then nebulized using nitrogen gas. The detection of fungicides is carried out on a single quadrupole using positive ionization and selected ion monitoring modes.