Screening of Carbamates and Ureas in Fresh and Processed Tomato Samples using Microwave-Assisted Extraction and Liquid Chromatography

Abstract

An analytical method, based on microwave-assisted extraction and liquid chromatography with diode array detection, for the determination of six carbamate and three urea pesticides in fresh and processed tomato samples is described. Significant parameters affecting extraction efficiency were optimized. Under optimum microwave-assisted extraction conditions (20 mL acetonitrile, for 10 minutes, at 60°C), pesticides were extracted with recoveries ranging from 57.6 to 102% (RSDs < 7%). Quantification limits between 6.5 and 39.6 µg/kg were obtained. A total number of 28 different fresh tomato samples and 6 processed tomato products were analysed. Confirmation of suspicious samples was performed by LC-MS.

Keywords:

• Carbamates
• liquid chromatography
• microwave-assisted extraction
• Pesticides
• tomato
• ureas

The authors wish to thank the Fundação para a Ciência e a Tecnologia (FCT) for the financial support through the project POCTI/AGR/44491/2002 (co-financed by FEDER).

Notes

R–correlation coefficient; y–peak area; x–concentration (µg/L);

^a –tomato;

^b –different fruits and vegetables;

^c –potato;

n.a.–use not allowed;

∗Portuguese Ministry of Agriculture (2008).

n.d.–not detected.