This document summarizes research analyzing the detection of common herbicides like atrazine in Iowa water systems using LC-MS/MS techniques. The research achieved detection limits below 1 ppb and differentiated similar compounds. Water samples from a river in North Central Iowa were tested and found to contain levels of atrazine that varied with precipitation, with concentrations up to 1.025 ppb. The LC-MS/MS method provided a fast and sensitive way to detect herbicides and complemented standard ELISA field tests.

1. Timothy J. McCall and Elaine M. Marzluff, Department of Chemistry, Grinnell College, Grinnell IA
Herbicide Usage in Iowa
Analytical Techniques in Environmental Chemistry:
Detection and Quantification of Common Herbicides
Detection Limit: <1 ppb
Instrumentation: Electrospray Source Quadrupole Collision Cell Time-of-Flight
• Atrazine used extensively in Iowa, to control broadleaf weeds in
corn crop
• Enzyme Linked Immunosorbent Assay (ELISA) gives false
positives due in part to detection of closely related compounds
• LC-MS useful for comparative analysis and differentiation of
similar compounds
Mode Run Time Set Mass (Da) CE (eV) LC Conditions
%A %B
MS 2-5 min N/A 6 (off) 97 3
MSMS 5-6 min 202 10 60 40
MSMS 6-7 min 216 17 60 40
MSMS 7-8.5 min 230 19 60 40
MS 8.5-10 min N/A 6 (off) 44 56
MS 10-12 min N/A 6 (off) 97 3
Figure 3. The chromatogram of standards of used for construction of an atrazine
calibration curve. These chromatograms were filtered to reduce noise and
improve the detection limit.
Figure 4. The calibration curve for the atrazine. Curve was constructed by filtering
chromatogram by each parent and product ion mass and solving for the
combined peak area.
Surface Water Samples
References and Acknowledgements
Adams, C.; Blute, N.; Graziano, N.; Jiang, H.; McGuire, M. J.; Roberson, A. 2004 National Atrazine Occurrence Monitoring Program Using the Abraxis
ELISA Method. Environ. Sci. Technol. 2006, 40, 1163-1171.
Grzyb, A.; Richardson, R.; Tomczyk, N.; Wallace, A., Wildgoose, J. Targeted High Resolution Quantification with Tof-MRM and HD-MRM; Technology Brief
for Waters, Inc.: Milford, MA, 2013.
Munch, D.J.; Pepich, B.V.; Smith, G.A. Determination of Triazine Pesticides and Their Degradates in Drinking Water by M=Liquid Chromatography
Electrospray Ionization Tandem Mass Spectrometry (LC/ESI-MS/MS); 815-B-07-002; EPA: Cincinnati, OH, 2007.
United States Geological Survey. Watershed Regression for Pesticides (WARP). http://infotrek.er.usgs.gov/warp/
Electrospray
Source (ESi)
Quadrupole Collision
Chamber Time-of-
Flight
(ToF)
Ions Produced
Ions Selected
Fragments
Produced
Detector
Ions are bombarded by argon gas in the
collision chamber to produce charged fragments
The Time-of-Flight analyzer accelerates ions
to different velocities depending on their m/z
The quadrupole can select specific ions to
pass through for monitoring and detection
The Electrospray source produces and isolates
ions from neutral analyte molecules and solvent
0.04-0.149 ppb
0.15-1.025 ppb
>1.026 ppb
Separated Sample
Matrix (from LC)
Compound
Parent Ion (m/z)
Product Ions (m/z)
Simazine
202
132
159
Atrazine
216
132
174
Propazine
230
146
188
Figure 2a. A chromatogram of a 30 ppb standard containing simazine, atrazine, and propazine.
2b. The combined mass spectra collected in MS/MS mode at a rate of 1 scan/sec. Each spectra,
except that of simazine, depicts the parent ion and characteristic fragment ions.
2c. The molecular structures of each parent ion and typical fragment ions.
Table 1. The LC conditions and MS method used for herbicide detection. The highlighted rows
correspond to the portions of the chromatogram in figure 2. Mobile phase consisted of water +
0.1% formic acid (A) and acetonitrile + 0.1% formic acid.
Table 2. A summary of the CID (collision induced dissociation) products present in figure 2.
Figure 5. A chromatogram of a surface
water sample run with the method
described in table 1. Each portion was
filtered by parent ion mass to improve the
peak to noise ratio.
Figure 1. A map of major waterways in Iowa and their predicted yearly average
concentration of atrazine based on usage in 2007. The star indicates roughly the
area where samples were collected for this project (North Skunk River). Model
adapted from USGS Watershed Regressions for Pesticides.
Figure 6. The total concentration of
atrazine in four water samples taken
over a three week period in June. Total
precipitation for the 48 hours preceding
sampling are shown above each bar.
A general schematic of a Q-ToF
tandem mass spectrometer. A
Waters Xevo Qtof with Acquity
UPLC was used in this research
Thank you to the National Science Foundation and Grinnell College for funding and support throughout the research process.
Thanks to Dr. Andrew Graham for his help with herbicide detection.
Overview
0
200
400
600
800
1000
6.4 6.5 6.6 6.7 6.8 6.9 7
Intensity
Time (min)
30 ppb
10 ppb
0
10
20
6 6.5 7
Intensity
Time (min)
1.0 ppb
0.3 ppb
c)
0
100
200
300
400
500
600
700
800
900
1000
5 5.5 6 6.5 7 7.5 8 8.5
Intensity
Time (min)
Simazine Atrazine Propazine
m/z m/z m/z
a)
b)
The prolific usage of atrazine and related herbicides poses a
significant risk to water supplies, especially in areas like Iowa with
high agricultural activity. We have adapted a standard protocol
using LC/MS/MS (Liquid Chromatography/Tandem Mass
Spectrometry) for the detection of herbicides. This laboratory
exercise is designed to complement standard field sampling
techniques, such as enzyme linked immunosorbent assay
(ELISA).
The LC/MS/MS analysis is fast with low detection limits,
demonstrates important instrumental features (collision induced
dissociation, MS/MS), and can be completed in a single
laboratory period. In this work, samples of local surface water
were probed for three common herbicides, atrazine, propazine,
and simazine, with minimal preparation. Overall, this instructional
laboratory utilizes important field and laboratory based techniques
in the context of a in environmental chemistry.
Results