Low Level Determination of Triazine Herbicides using LC/MS with a New Field Free APCI Source

Low Level Determination of Triazine Herbicides using LC/MS with a New
Field Free APCI Source
Avinash Dalmia; Thomas White; Daniel Pentek
PerkinElmer Inc., Shelton, CT
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Objectives
Develop a reverse phase HPLC method to detect
triazine herbicides (propazine, atrazine, terbutylazine, simazine and irgarol) using a single
quadrupole MS detector with field free APCI source
Determine the detection limits for 5 triazine herbicides
Study the effect of a nitrogen supply hydrocarbon trap
on sensitivity determination of 5 triazine herbicides
Study the fragmentation pattern of triazine herbicides
compounds using APCI and capillary exit collision
induced decomposition (CID) in positive ionization
mode
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SIM of 10 pg Injected on column of
5 Triazine Herbicides
Method
Total Ion Chromatogram (TIC)
10 pg Simazine
(+) SIM at 202.2 u
Cap. Exit= 90 V
Atrazine
Injection amt.: 1ng on column
Scan range: m/z 120-300
Scan speed: 1000 u/s
Triazine Herbicides Detection Limits
Compound
3pg (S/N)
LOD (pg)
LOQ (pg)
Atrazine
63
0.14
0.48
Simazine
11
0.82
2.73
Propazine
31
0.29
0.97
Ter-butylazine
18
0.50
1.67
Irgarol
29
0.31
1.03
10 pg Atrazine
(+) SIM at 216.2 u
Cap. Exit= 90 V
Propazine
Irgarol
Ter-butylazine
10 pg Propazine & Ter-butylazine
(+) SIM at 230.2 u
Cap. Exit= 90 V
Propazine
Ter-butylazine
Simazine
10 pg Irgarol
(+) SIM at 254.2 u
Cap. Exit= 90 V
FlexarTM
HPLC: PerkinElmer
FX-10
MS: PerkinElmer FlexarTM SQ 300 MS with PerkinElmer field free APCI source
Column: PerkinElmer Brownlee Supra C18, 3 µm, 2.1 x 100 mm
Gradient: 60 % MeOH to 85 % MeOH in water, 5 mM ammonium formate
in 7 min at 0.5 mL/min
APCI source temperature: 300 oC
Corona Current: 5 µA
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Results & Discussion
Mass Spectra of Triazine Herbicides
[M+H]+
Simazine
Background spectra with and without a
hydrocarbon trap.
Isobaric Compounds (Propazine and
Ter-butylazine) Differentiated by CID
[M+H-C2H4]+
Background Spectra with Hydrocarbon Filter
The LOD of all 5 triazine herbicides was lower than 1 pg
Ter-butylazine fragment
(+) SIM at 174.2 u
Cap. Exit= 150 V
Atrazine
5
[M+H]+
Propazine fragment
(+) SIM at 188.2 u
Cap. Exit= 150 V
Summary
• A seven minute HPLC-MS method was
developed for measurement of 5 triazine
herbicides
[M+H-C3H6]+
Background Spectra with No Hydrocarbon Filter
[M+H]+
Propazine
Field Free APCI Source Performance: 4
Orders of Magnitude Linear Dynamic Range
[M+H-C3H6-C3H6]+ [M+H-C3H6]+
Atrazine
Simazine
[M+H]+
216.1 u
202.1 u
4
11
63
230.1 u
30
31
Ter-butylazine
230.1 u
18
18
254.1 u
32
Ter-butylazine
[M+H-C4H8
]+
[M+H]+
11
Propazine
Irgarol
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Log (Response ) (counts)
Compound
9
3pg (S/N) with no
3pg (S/N) with
hydrocarbon trap hydrocarbon trap
[M+H-C4H8-C2H4]+
• With a hydrocarbon trap, the detection
limit for atrazine was improved by a
factor of 15; the detection limits for the
other 4 triazine herbicides was
unaffected
7
6
5
4
3
• The field free APCI source response was
linear over 4 orders of magnitude
2
29
Irgarol
Using a hydrocarbon trap for the nitrogen gas, supply, the
detection limits for atrazine improved by a factor of 15 due to
removal of impurity at m/z 214.1 which could be due to presence
of n-butyl benzene sulfonamide. The sensitivity for the other
triazine herbicides did not improve due to hydrocarbon filtering
of the nitrogen supply.
y = 0.99x + 4.1744
R² = 0.9996
[M+H-C4H8]+
[M+H]+
• The isobaric compounds (propazine and
ter-butylazine) were differentiated
further by measuring their different
fragments using in-source CID
1
0
0
0.5
1
1.5
2
2.5
Log ( Atrazine) (pg)
3
3.5
4
4.5
• Using an optimized LC-MS method, the
detection limits of five triazine herbicide
compounds ranged from 0.14 to 0.82 pg
injected on column
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