2.3. Analysis
Analysis of the target pesticides in water was performed by on online
solid phase extraction–liquid chromatography–tandem mass
spectrometry (SPE–LC–MS/MS) as described in Köck-Schulmeyer et al.
(2012, 2013).
Briefly, 5 mL of the water samples (previously filtered and spiked
with the deuterated surrogate standards at 200 ng L−1) and the
standard calibration solutions were extracted with an automated online
SPE sample processor, Prospekt-2 (Spark Holland, Emmen, The
Netherlands), connected in series with the LC–MS/MS instrument,
using two types of disposable trace enrichment polymeric cartridges
(Hysphere Resin GP and PLRP-s, both from Spark Holland). The
Hysphere Resin GP cartridge was used for the extraction of 6 pesticides
that were measured in the negative ionisation (NI) mode, and the
PLRP-s cartridge was used for the extraction of the pesticides that
were measured in the positive ionisation (PI)mode (19 compounds)
(see Table 1). After sample loading, the cartridges were washed with
1 mL of water and eluted with the chromatographic mobile phase.