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Analysis of Glyphosate and AMPA in
Environmental Water by Ion Chromatography
Electrospray TandemMass Spectrometry
(IC-ESI-MS/MS)
Charles Yang
1
, Stacy Henday
2
, Leo Wang
2
, and Bill Schnute
2
1
Thermo Fisher Scientific, San Jose, CA;
2
Dionex Corporation, Sunnyvale, CA
Introduction
Glyphosate [N-(phosphonomethyl) glycine] is a
nonselective herbicide that inhibits the shikimic acid
pathway in plants. Glyphosate is the most commonly used
agricultural pesticide and the second most used pesticide
around homes and gardens.
1
It is applied to control
woody and herbaceous weeds in forestry, cropped, and
non-cropped sites. Although the bacteria in soil break
down glyphosates into aminomethylphosphonic acid
(AMPA), wastewater discharge samples and drinking
water samples in the United States and Europe have tested
positive for glyphosate.
2-4
Studies have raised global health
and environmental concerns about the usage of
glyphosate.
5
In 2006, the US EPA set the minimum
contaminant level (MCL) for glyphosate at 0.7 mg/L.
6
Long-term exposure to glyphosate at levels above the
MCL may cause kidney damage and reproductive defects
in human biological systems.
The U.S. EPA established Method 547 for the
determination of glyphosate in drinking water by direct
aqueous injection high pressure liquid chromatography
(HPLC), post-column derivatization, and fluorescence
detection. Other methods for the quantitation of
glyphosate typically use preliminary derivatization or
solid-phase extraction (SPE) followed by post-column
derivatization. Silica-based reversed-phase C18 columns,
which use cation-exchange mechanisms, experience
difficulty with the retention of such polar compounds.
Here, we present a two-dimensional technique that
separates glyphosate and AMPA by using anion-exchange
columns coupled to a triple stage quadrupole mass
spectrometer. This system eliminates the need for
derivatization and preparation of complex mobile phases.
Goal
To develop an ion chromatography-mass spectrometry
(IC-MS/MS) method to separate and quantitate glyphosate
and AMPA without derivatization or preparation of
complex mobile phases.
Experimental Conditions
Ion Chromatography
IC analysis was performed on a Dionex ICS 3000 ion
chromatography system (Dionex Corporation, Sunnyvale,
CA). Samples were directly injected and no sample pre-
treatment was required. The IC conditions used are as
follows:
First Dimension
Column set:
IonPac
®
AG19 (2.1 × 50 mm) / AS19
(2.1 × 250 mm); guard and separator columns
(Dionex)
IonPac UTAC (3 × 50 mm) Ultratrace anion
concentrator column (Dionex)
Suppressor:
ASRS
®
300, 2 mm; operated at 30 mA (Dionex)
Column temperature:
30 °C
Injection volume:
200 µL
Mobile phase:
Potassium hydroxide, electrolytically generated with
an EGC-KOH cartridge
Gradient:
0–12 min: 8 mM KOH
12–16 min: 8–40 mM KOH
16–21 min: 40 mM KOH
Flow rate:
300 µL/min
Second Dimension
Column set:
IonPac AG21 (2.1 × 50 mm) / AS21
(2.1 × 250 mm); guard and separator columns
(Dionex)
Suppressor: ASRS 300, 2 mm; operated at
48 mA (Dionex)
Column temperature:
35 °C
Mobile phase:
Potassium hydroxide, electrolytically generated with
an EGC-KOH cartridge
Gradient:
0–20 min: 1 mM KOH
20–30 min: 1–40 mM KOH
30–35 min: 40 mM KOH
Flow rate:
300 µL/min
Key Words
• TSQ Quantum
Access
• Ion
chromatography
• EPA
• Herbicides
• Water analysis
Application
Note: 491