Determination of carbamate residues in fruits and vegetables by matrix solid-phase dispersion and liquid chromatography-mass spectrometry

Thirteen carbamates were analysed in orange, grape, onion and tomatoes by m atrix solid-phase dispersion (MSPD) followed by liquid chromatography-mass spectrometry (LC-MS). Electrospray (ES) and atmospheric pressure chemical i onisation (APCI) were compared and both gave similar results in terms of se nsitivity and structural information because at 20 V fragmentor voltages th e fragmentation is minimal. The efficiency of different solid-phases (C-18, C-8, cyano, amine and phenyl) for the MSPD was compared. Mean recoveries u sing C-8 varied from 64 to 106% with relative standard deviations of 5-15% in the concentration range of 0.01-10 mg kg(-1). Matrix constituents did no t interfere significantly with the ionisation process of carbamates. The li mits of detection were typically in the 0.001-0.01 mg kg(-1) range, which w ere between 10 and 100 times lower than the maximum residue levels (MRLs) e stablished by the European Union (EU). The method was applied to residue de tection in fruit and vegetable samples taken from Valencian markets, in whi ch carbamates were detected at low concentrations. (C) 2000 Elsevier Scienc e B.V All rights reserved.