Liquid chromatography–electrospray ionization–timeof-
flight mass spectrometry (LC–ESI–TOF-MS), in positive
ionization was used to detect the pesticides. The separation
of the selected pesticides was carried out using an HPLC
system (consisting of vacuum degasser, autosampler and a
binary pump) (Agilent Series 1100, Agilent Technologies,
Palo Alto, CA, USA) equipped with a reversed-phase C8
analytical column of 150mm×4.6mm and 5m particle
size (Zorbax Eclipse XDB-C8). Column temperature was
maintained at 25 ◦C. The injected sample volume was 50 l.
Mobile phasesAandBwere acetonitrile andwater with 0.1%
formic acid, respectively. The optimized chromatographic
method held the initial mobile phase composition (10% A)
constant for 5 min, followed by a linear gradient to 100% A
in 25 min. The flow-rate usedwas 0.6 ml/min.A12-min postrun
time back to the initial mobile phase composition was
used after each analysis. This HPLC system was connected
to a time-of-flight mass spectrometer Agilent MSD TOF
(Agilent Technologies) with an electrospray interface, using
the operational parameters included in Table 1. LC–TOF-MS