Hello everyone
my name is Benjamin Wuyts, I'm a
Applications Chemist at Waters and I
provide post-sales support to customers
who are struggling with our analysis on
quadrupole-based mass spectrometry instruments.
Besides on-site support I'm also heavily
involved in internal method development
to generate fit-for-purpose solutions
for challenging applications. I recently
developed a method for the direct
analysis of glyphosate and other anionic
polar pesticides using the latest
addition in our family of
Xevo tandem quadrupoles, 
the Xevo TQ-XS. Due to the potential harmful
nature of these commonly used pesticides
their concentration should be closely
monitored in food, soil, and water samples.
Routine testing of these analytes can be
challenging as they're highly polar
physical chemical characteristics do not
lend them to the traditional multi-residue
methods by reversed-phase chromatography.
I carried out all testing by direct
analysis using electrospray negative
ionization, which can be easily
configured in the system's tune page.
Different food samples were prepared
using the EURL quick pour pesticides
extraction protocol and I achieved
excellent levels of sensitivity,
well below the maximum residue levels
enforced in Europe and other global legislation.
Using the benefits of the
Xevo TQ-XS's source design and StepWave
technology, we can achieve excellent
levels of sensitivity, robustly, without
the need for derivatization. During
initial development I found it difficult
to maintain good peak shape for several
polar pesticides. This was experienced
across many chromatographic column
chemistries and during extensive runs of
food samples I observed significant peak
tailing, especially for glyphosate, which is
a known challenge in polar pesticide
analysis nowadays. However, by choosing
the correct column and using our
chemically clean UPLC system, I was
able to generate robust methods,
maintaining good results with Gaussian
peak shape. This provided UPLC
retention time stability performance
over large batches of food matrices. Also,
since samples were analyzed in the
absence of isotopically labeled internal
standards, I used standard addition
calibration in TargetLynx XS.
This is allowed for the accurate
quantification of chlorate and  phosphonic
acid in beer and tomato juice all in
compliance with the 2015 SANTE
guidelines as well as enforced anywhere else.
