Abstract
A new multi-residue method for determination of pesticide residues in a wide variety of fruit and vegetables, using the National Food
Administration (NFA) ethyl acetate extraction and determination by means of LC–MS/MS, is presented. The method includes pesticides nor-
mally detected by LC–UV or LC-fluorescence such as benzimidazoles, carbamates, N-methylcarbamates and organophosphorus compounds
with an oxidisable sulphide group as well. After extraction with ethyl acetate, the extract is concentrated and an aliquot of the extract is evap-
orated to dryness and redissolved in methanol before injection on LC–MS/MS. The method has been validated for 57 different pesticides and
metabolites. Representative species from different commodity groups were chosen as matrices in order to study the influence from different
matrices on recoveries. The fortification levels studied were 0.01–0.5mg kg−1
.Matrix effects were tested for allmatrices bymeans of standard
addition to blank extracts. The matrix effect, expressed as signal in solvent compared to signal in matrix, was in general found to be small. The
obtained recoveries are, with a few exceptions, in the range 70–100%. The proposed method is quick and straightforward and no additional
clean-up steps are needed. The method can be used for the analysis of all 57 pesticides in one single determination step at 0.01mg kg−1
.
© 2003 Elsevier B.V. All rights reserved.
Keywords: Fruit; Vegetables; Multi-residue analysis; Pesticides
1. Introduction
For the national authorities responsible for monitoring
pesticide residues in food and vegetables, multi-residue
methods are highly preferable due to the simplicity of de-
tecting several analytes in a single extraction. Multi-residue
methods facilitate the demands of more efficient moni-
toring, when the authorities have to create the necessary
conditions for monitoring new pesticides. Multi-residue
methods usually used in pesticide analysis are designed for
determination with gas chromatographs with different se-
lective detectors. In contrast to older, non-polar pesticides,
modern, recently introduced pesticides are often more po-
lar and less volatile. This complicated nature of pesticides
Presented at the Fourth European Pesticide Residue Workshop
(EPRW 2002), Rome, 28–31 May 2002.
∗ Corresponding author. Fax: +46-18105848.
E-mail addresses:
[email protected] (C. Jansson),
[email protected] (T. Pihlström).
gives rise to the development of special methods which are
intended for analysis of a certain pesticide or group of pes-
ticides. Several special methods have thus been used in the
Swedish monitoring of pesticide residues [1]. The special
methods include pesticides normally detected by LC–UV
or LC-fluorescence such as benzimidazoles, carbamates and
N-methylcarbamates. The LC–UV methods often have low
sensitivity, while the fluorescence methods normally have
better sensitivity. Both techniques lack sufficient selectiv-
ity towards endogenous compounds, which absorb at the
same wavelength. These methods are often time-consuming
and costly, including several steps in sample preparation.
Therefore, it was decided to develop a multi-residue method
which could replace the special methods and create a foun-
dation for more efficient monitoring.
Liquid chromatography/mass spectrometry (LC–MS) has
been used for analysis of these compounds and is rapidly
becoming an accepted technique in pesticide residue anal-
ysis for regulatory monitoring purposes. Recent reviews in
0021-9673/$ – see front matter © 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.chroma.2003.10.019
