High Sensitivity GC/MS/MS Analysis of
Nonpolar Organic Compounds in Water
Using the Agilent 7000 Triple Quadrupole
GC/MS
Application Note
Environmental
Authors
Abstract
John Quick and Richard Glendinning
A highly sensitive and reliable method has been developed for 51 nonpolar com-
Severn Trent Services
pounds in potable water, and PBDEs, PAHs, and diazinon in wastewater. Most MRLs
Coventry,
in potable water were 2 ng/L or less, and the MRLs for the analytes in wastewater
United Kingdom
less than 0.2 ng/L for some compounds. Run time is less than 20 minutes, sample
Adrian Thomas
Severn Trent Services
Bridgend,
United Kingdom
preparation is straight forward, and the potable water method is accredited by the
UKAS.
Introduction
The environmental analysis of nonpolar organic compounds, including pesticides
and polychlorinated biphenyls (PCBs), has traditionally been done using gas chromatography (GC) with electron capture detection (ECD). Two columns with differing
modes of separation are often needed to confirm identity of the compounds, since
the ECD detector does not provide any structural information. As a result, GC/ECD
methods can be time-consuming and tedious due to the use of two columns, and
can be sensitive to interferences which can reduce sensitivity and the ability to
confirm identity.
The use of GC and tandem mass spectrometry (MS/MS) can eliminate interferences
problematic with GC/ECD, while providing the required sensitivity and high-confidence compound identification. Environmental analyses for nonpolar organic compounds can benefit by transitioning to a GC/MS/MS platform.
Severn Trent Services, in the United Kingdom, has successfully made this transition, using the Agilent 7000 Triple
Quadrupole GC/MS to provide required limits of detection
(LODs) and precision requirements for a suite of 51 nonpolar
organic compounds in potable water, including chlorinated
pesticides and PCBs. Using a single DB column and two multiple reaction monitoring transitions per analyte, Severn Trent
has developed a method with a 12-minute run time and as
little as 15-minute cycle time, better selectivity, enhanced
sensitivity and robustness, and easier data processing
compared to the previous GC/ECD method.
cooling, high selectivity through the use of two transitions per
compound, and easier data processing through the use of
Agilent MassHunter software.
Method Validation
The method was validated for the analysis of 51 compounds
in five water matrices: soft, medium, and hard potable water;
borehole and surface raw water. Most of the compounds contained organochlorine, and they exhibited a large volatility
range (Table 1). The laboratory precision target was less than
12.5%. The UK prescribed concentration values (PCVs) for
presence in potable water are 0.1 µg/L for individual pesticides. Method validation with water of medium hardness
spiked at PCV levels resulted in recoveries no lower than
98.4% and no higher than 105.1%, with RSDs as low as 2.1%
and no higher than 7.1% (Table 2). Over three months, the
RSDs ranged from 1.6 to 7.4%, with 43 of the 51 compounds
having RSDs below 5%. Figure 1 illustrates some typical
results for the hexachlorohexane (HCH) delta isotope over a
three month period.
This application note presents the results obtained using this
method to analyze both potable water and wastewater. The
highest limit of detection (LOD) in potable water with minimal
sample prep was 3 ng/L for captan, all others were
2 ng/L or less, well below the LOD requirement of < 0.025 µg/L.
Recoveries ranged from 99.5 to 105.1% for compounds spiked
into water of medium hardness (200 mg/L CaCO3) at the UK
prescribed concentration value (PCV), with the majority of the
relative standard deviations (RSDs) below 5%. The method
has also been used for crude sewage and industrial effluents,
with more extensive sample preparation. These matrices are
held to very low detection limits, and this method can provide
method reporting limits (MRLs) less than 1 ng/L for some
compounds. The method is accredited for potable water by
the United Kingdom Accreditation Service (UKAS) and is used
routinely at Severn Trent Services for analysis of potable
water.
Table 1.
The 51 Compounds Analyzed Using the GC/MS/MS Method
1,2,4-Trichlorobenzene
p,p’-DDE
PCB 28
Hexachlorobutadiene
Dieldrin
PCB 52
Dichlobenil
o,p’-TDE
PCB 101
alpha-HCH
Endrin
PCB 118
beta-HCH
beta-Endosulphan
PCB 153
Hexachlorobenzene
p,p’-TDE
PCB 138
gamma-HCH
o,p’-DDT
PCB 180
Results and Discussion
delta-HCH
p,p’DDT
Cyfluthrin
Chlorothalonil
Methoxychlor
Cypermethrin
Method Development
Heptachlor
Captan
Fenvalerate
Aldrin
EPTC
Deltamethrin
Isodrin
Tecnazene
Phorate
cic-Heptachlor Epoxide
Trifluralin
Tri-allate
trans-Heptachlor Epoxide
Disulphoton
Chlorpyritos-methyl
o,p’-DDE
Fenitrothion
Parathion-ethyl
alpha-Chlordane
cis-Permethrin
Chlorpyrifos-ethyl
alpha-Endosulphan
trans-Permethrin
Carbophenothion
Moving the method from a GC/MS/ECD platform to
GC/MS/MS on the Agilent 7890 Series GC and 7000 Triple
Quadrupole GC/MS required only a slight modification in the
liquid extraction method. A DB1 column provided good separation of DDT isomers, and the multimode inlet enabled large
injection volumes, eliminating the need for a time consuming
solvent evaporation step. Moving the method to GC/MS/MS
made possible cycle times less than 15 minutes with cryo
2
Table 2.
Method Validation Results for Potable Water of Medium Hardness
Med. water - PCV spike
Med. water - PCV spike
Med. water - PCV spike
Name
Recovery
RSD
Name
Recovery
RSD
Name
Recovery
RSD
EPTC
105.1%
2.9%
trans-Heptachlor epoxide
104.0%
6.8%
Methoxychlor
100.7%
6.3%
124-TCB
100.3%
3.3%
Dieldrin
100.6%
8.3%
PCB 180
100.9%
4.8%
Hexachlorobutadiene
101.6%
5.2%
Isodrin
101.8%
4.5%
cis-Permethrin
102.2%
3.5%
Dichlobenil
103.1%
3.5%
o,p’DDT
100.7%
3.7%
trans-Permethrin
102.0%
3.3%
Tecnazene
102.7%
5.1%
PCB 101
101.3%
3.7%
Cyfluthrin
99.1%
3.4%
Trifluralin
104.3%
3.8%
alpha-Chlordane
99.5%
4.7%
Cypermethrin
100.6%
3.0%
alpha-HCH
101.6
2.9%
alpha-Endosulphan
102.3%
3.3%
Fenitrothion
100.6%
4.7%
Hexachlorobenzene
101.7%
4.8%
p,p’-DDE
101.0%
3.5%
Deltamethrin
98.4%
6.9%
gamma-HCH
101.6%
2.6%
OP-TDE
100.7%
4.0%
delta-HCH
102.0%
2.6%
beta-HCH
101.9%
3.0%
PCB 118
100.9%
3.3%
Triailate
104.1%
3.9%
PCB 28
102.9%
4.4%
PP-TDE
100.8%
4.5%
Parathion-ethyl
100.7%
3.2%
Chlorothalonil
107.8%
3.6%
Endrin
98.9%
7.2%
Carbophenothion
99.9%
5.6%
Heptachlor
104.7%
6.0%
op-DDT
102.8%
5.4%
Chlorpyritos-methyl 101.0
2.4%
PCB 52
100.8%
5.0%
PCB 153
100.5%
3.6%
Chlorpyrifos-ethyl
100.7%
2.7%
Fenitrothion
103.5%
3.9%
beta-Endosulphen
103.1%
3.7%
Captan
101.5%
5.4%
Aldrin
104.2%
5.8%
PCB 138
100.5%
3.1%
Phorate
101.1%
2.5%
cic-Heptachlor epoxide
104.0%
7.1%
pp-DDT
101.1%
2.1%
Disulphoton
102.1%
2.1%
0.106
0.104
0.102
0.100
0.098
0.096
0.094
22/06/12
09/07/12
Used: Mn: 0.09959
17/07/12
Sd: 0.00187
23/07/12
26/07/12
27/07/12
Ual: 0.1052
06/08/12
Uwt: 0.10333
14/08/12
20/08/12
Lwt: 0.09585
30/08/12
31/08/12
Lal: 0.09398
07/09/12
Norm: 01
Figure 1. Analytical quality control (AQC) results for analysis of hexachlorocyclohexane (HCH) delta spiked into water at 0.1 µg/L, over a three month period.
Applying the method to wastewater specifically for the analysis of PBDEs, PAHs, and diazinon required more extensive
sample preparation than was required for the 51 nonpolar
organic compounds in potable water. The run time is also
slightly longer owing to the need to separate Benzo(b) and (k)
Fluoranthene.
Method Performance
R2
The method routinely provided calibration curves with
values >0.998 for a concentration range of 10 to 120 ng/L.
Chromatographic separation was sufficient to separate the
isomers of DDT in potable water for example, as well as the
HCH isomers (Figure 2).
3
This version of the method meets the requirement for low
method reporting limits (MRLs) in wastewater for these analytes, with some compounds having MRLs <0.2 ng/L. In these
dirty matrices, including crude sewage, the sensitivity and
selectivity of GC/MS/MS are essential. For example, the
method easily detects cypermethrin in crude sewage at
2.5 ng/L and PBDE 47 at 1 ng/mL (Figure 3). The dynamic
range of the method enables detection of diazinon in landfill
A
leachate at 0.7 ng/L, and 1,300 ng/L in effluent from a dyeing
plant (Figure 4). The lower MRLs for the wastewater method
are due to a greater concentration factor during sample
preparation, compared with the potable water method. The
sensitivity and selectivity of the 7000 Triple Quadrupole
GC/MS enables these LODs across a range of difficult matrix
types, which would be impossible with a mass selective
detector (MSD) and/or conventional detectors.
×106
2.4
2.2
2
1.8
Counts
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
3
4
4.5
5
5.5
6
8
6.5
7
7.5
Acquisition time (min)
8.2
8.3
8.5
9
9.5
10
10.5
11
11.5
×105
1.2
1.1
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Counts
B
3.5
7.5
C
7.6
7.7
7.8
7.9
8
8.1
8.4
8.5
8.6
8.7
8.8
8.9
9
9.1
9.2
9.3
9.4
6.15
5.2
6.25
Acquisition time (min)
×104
3.2
2.8
Counts
2.4
2
1.6
1.2
0.8
0.4
0
5.25
5.3
5.35
5.4
5.45
5.5
5.55
5.6
5.65 5.7 5.75 5.8 5.85
Acquisition time (min)
5.9
5.95
6
6.05
6.1
Figure 2. Representative chromatograms for: A. Total ion current (TIC) of 51 nonpolar compounds spiked at 120 ng/L into potable water of medium hardness;
B. Extracted ion current (EIC) for DDT isomers spiked at 10 ng/L; C. EIC for four HCH isomers spiked at 10 ng/L.
4
Cypermethrin at 2.5 ng/L in crude sewage
×103
3.5
13.840 min
Cypermethrin
2.4247 ng/L
9818
Counts
3
2.5
2
1.5
1
0.5
13.68
13.7 13.72 13.74 13.76 13.78 13.8
13.82 13.84 13.86 13.9 13.92 13.94 13.96 13.98 10.5
Acquisition time (min)
14
14.02 14.04 14.06 14.08
PBDE 47 at 1 ng/L in crude sewage
×103
12.007 min
PBDE 47
1.2635 ng/L
1189
1
Counts
0.8
0.6
0.4
0.2
0
11.84
11.86
11.88
11.9
11.92
11.94
11.96
11.98
12
12.02 12.04
Acquisition time (min)
12.06
12.08
12.1
12.12
12.14
12.16
12.18
Figure 3. Analysis of very low levels of cypermethrin and PBDE 47 in crude sewage.
Diazinon at 0.7 ng/L in landfill leachate
6.886 min
Diazinon
0.7439 ng/L
63
Counts
×101
8
7
6
5
4
3
2
1
0
6.70 6.72 6.74 6.76 6.78
6.8
6.82 6.84 6.86 6.88 6.90 6.92 6.94 6.96 6.98 7.00 7.02 7.04 7.06 7.08 7.10 7.12 7.14 7.16 7.18
Acquisition time (min)
Diazinon at 1,300 ng/L in a dyeing works effluent
6.877 min
Diazinon
1369.3646 ng/L
428409
×105
Counts
4
3
2
1
0
6.70 6.72 6.74 6.76 6.78
6.8
6.82 6.84 6.86 6.88 6.90 6.92 6.94 6.96 6.98 7.00 7.02 7.04 7.06 7.08 7.10 7.12 7.14 7.16 7.18
Acquisition time (min)
Figure 4. Dynamic range of analysis of diazinon in wastewater.
5
Conclusion
A sensitive and reliable GC/MS/MS method has been developed on the Agilent 7000 Triple Quadrupole GC/MS that provides required LODs and precision for analysis of 51 nonpolar
organic compounds in potable water. It also enables detection
of as low as sub-1 ng/L (ppt) levels in wastewater for PAHs,
PBDEs and organochlorine pesticides. It is rapid and robust,
with a cycle time as little as 15 minutes and recovery RSDs
that did not exceed 7.4% for all 51 compounds in potable
water over a three month period. This method is UKAS
accredited for potable water and has been in routine use in
this laboratory for several months.
For More Information
These data represent typical results. For more information on
our products and services, visit our Web site at
www.agilent.com/chem.
www.agilent.com/chem
Agilent shall not be liable for errors contained herein or for incidental or consequential
damages in connection with the furnishing, performance, or use of this material.
Information, descriptions, and specifications in this publication are subject to change
without notice.
© Agilent Technologies, Inc., 2013
Printed in the USA
January 16, 2013
5991-1553EN