Potentiality of Gas Chromatography-Triple Quadrupole Mass Spectrometry in Vanguard and Rearguard Methods of Pesticide Residues in Vegetables
A new analytical strategy for the screening and confirmation/
quantification of multiclass pesticide residues in
vegetables has been established and validated. No complicated
sample preparation was needed, but only a
simple and rapid extraction using ethyl acetate and
sodium sulfate, which required no cleanup. The approach
is based on the use of the triple quadrupole (QqQ) mass
spectrometry (MS) as detection system in gas chromatography
(GC). In a first step, a GC-QqQ-MS screening
method, which monitors only one MS/MS transition by
compound, allows the identification of 130 pesticides
in 11.6 min. In this way, the differentiation between
negative and potentially nonnegative samples is carried
out. In the second step, the nonnegative samples are
reanalyzed by the GC-QqQ-MS confirmation/quantification
method, which monitors two or three MS/MS transitions
by compound. Confirmation of pesticides was based
on the comparison of intensity ratios for the main ions in
samples with those obtained on the same day from the
standard in a matrix containing the pesticides at a
preestablished concentration level. Quantification of the
identified and confirmed pesticides was based on the
addition standard method, which avoids matrix effect. The
proposed analytical strategy allowed a reliable identification
and confirmation of the target pesticides at trace
levels, reducing analysis time and increasing sample
throughput in routine analytical laboratories.
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