From Helium to Hydrogen:
Case Study in the GC-MS Analysis
of VOCs and SVOCs
Sergio Guazzotti, Alexander N. Semyonov, Jessie Butler,
Thermo Fisher Scientific, Austin, Texas, USA
Overview
Results
Purpose: EPA Methods 8270, 524, and 525 were optimized with hydrogen carrier gas
Stabilization Bake out for H
Methods: Hydrogen carrier gas was configured by using a smaller ID column and adding a hydrogen kit to a mass
spectrometer
When switching from helium
no gas filters are necessary.
of hydrogen is used, grade U
spectrometer. The source te
is turned on for one hour dur
source temperature was set
contamination off the entire f
present in the gas lines, a m
ionization and protonation ar
observed in the calibration g
Results: Peak shape, resolution, and run time improved
Introduction
The global helium shortage and price increase of this non-renewable noble gas cause more and more laboratories to
migrate to the use of hydrogen as a carrier gas. This transition is easy for the GC methods utilizing FID, TCD, ECD,
and other non-mass-selective detectors. However, for the GC-MS methods, especially complex and regulated ones,
migration to hydrogen carrier gas presents significant challenges. In addition to the changes in chromatographic
conditions of the run due to the physical property differences of hydrogen, its reactivity brings about chemical
reactions in the mass spectrometer’s ion source that do not occur with the use of helium.
The analyses of semi-volatile organic compounds (SVOCs) in wastewater by EPA Method 82701 and volatile organic
compounds (VOCs) in drinking water by EPA Methods 5242 and 5253 involve identification and quantitation of well
over a hundred analytes of varying chemical structure, polarity, and volatility. The diversity of the analytes in this
method presents particular challenges when migrating from helium to hydrogen carrier. GC-MS analysis of SVOCs
was performed on a Thermo Scientific™ TRACE™ 1310 GC coupled to a Thermo Scientific™ ISQ™ Series single
quadrupole mass spectrometer utilizing helium and hydrogen carrier gases. Key modifications to both GC and MS
hardware and methods are necessary for successful migration to hydrogen carrier gas. The final, optimized EPA
methods were migrated to hydrogen carrier gas with improved peak shape, resolution, and run time.
FIGURE 2. Air/water spectr
m/z 18
Methods
m/z 19
Sample Preparation
For EPA Method 8270, standards were prepared in methylene chloride. A performance mix containing
pentachlorophenol, DFTPP, benzidine, and p,p’-DDT was made at a concentration of 50 ppm. A calibration curve was
prepared from 1 to 200 ppm with internal standards and surrogates at 40 ppm. For EPA Method 524, a 5 mL volume
of water was used in a purge and trap concentrator (Eclipse 4660 Purge-and-Trap Sample Concentrator, OI
Analytical),and a calibration curve from 0.4 to 200 ppb was run. For EPA Method 525, a 1 L volume of water was
extracted with ethyl acetate. A calibration curve was run from 0.1 to 10 ppm.
m/z 28
Gas Chromatography
FIGURE 4. Cal Gas (FC-43)
For EPA Methods 525 and 8270, an Instant Connect split/splitless injector module was used in the split mode. A one
microliter injection was made. The standard Thermo Scientific™ TraceGOLD TG-5MS capillary column (30 m × 0.25
mm × 0.5 µm film) was replaced with a TraceGOLD TG-5MS column of smaller ID (20 m × 0.18 mm × 0.36 µm film).
For EPA Method 524, a purge and trap (P&T) adapter was used to make the injection of gases purged from water
sample of 5 mL volume onto a TraceGOLD TG-VMS column of smaller ID (20 m × 0.18 mm × 1.0 µm film).
Mass Spectrometry
The ISQ Series mass spectrometer was equipped with a hydrogen kit. The instrument was preconditioned by baking
it out with an elevated hydrogen carrier flow rate with the EI ion source filament turned on for one hour.
Data Analysis
Data was acquired using Thermo Scientific™ Xcalibur™ 2.0 software and processed using either Thermo Scientific™
Target 4.14 or Thermo Scientific™ TraceFinder™ 3.0 software. The Xcalibur software was configured for direct target
processing. A typical chromatogram of a 40 ppm standard is shown in Figure 1.
FIGURE 1. TIC of 40 ppm EPA Method 8270 standard with hydrogen carrier gas.
RT: 0.00 - 13.27
Selecting the Appropriate
NL:
5.35E8
TIC MS
level8
6.83
100
95
Due to the lower viscosity of
min of column flow rate. By
the reduction in the vapor vo
90
85
3.85
80
8.98 9.19
7.90
70
4.56
65
Relative Abundance
FIGURE 6. Comparison of
10.24
75
6.26
5.18
60
55
5.65 6.08
6.45
3.88
45
8.41
11.16
4.61
3.34
40
4.67
5.02
11.44
9.76
7.01
4.26
35
11.19
8.06
5.34
50
12.35
10.27
7.64
6.97
9.45
7.37
11.72
10.79
8.84
12.55
5.95
30
9.97
25
3.31
20
FIGURE 7. Methylene Chlo
15
2.25
1.80
2.98
RT: 0.000 - 13.008
2.51
100
5
8.48
10.54
12.17
0
0
1
2
3
4
5
6
7
Time (min)
8
9
10
11
12
90
12.70
80
13
Relative Abundance
10
4.039
70
60
50
3.016
40
30
1.368
20
10
2.002
3.281
0
100
90
80
70
3.730
60
50
2.719
40
30
2 From Helium to Hydrogen: Case Study in the GC-MS Analysis of VOCs and SVOCs
20
10
1.079 1.526
0
0
1
2.681
2
3.000
3
4.3
4
Peak Shape and Resolution
Results
The advantage of hydrogen carrier g
spending less time in the stationary
narrower peak width, and the critical
Stabilization Bake out for Hydrogen Carrier Gas
and adding a hydrogen kit to a mass
When switching from helium to hydrogen carrier gas, a brief stabilization period is required. If using a hydrogen generator,
no gas filters are necessary. Gas lines should be plumbed with new, pre-cleaned 1/8 in. stainless steel tubing. If a cylinder
of hydrogen is used, grade UHP 5.0 or better is required with in-line gas purifiers. The hydrogen kit is installed in the mass
spectrometer. The source temperature is set to 350 °C for bake out. The hydrogen carrier is set to 4 mL/min. The filament
is turned on for one hour during the bake out period. After bake out, the hydrogen flow is reduced to 1 mL/min, and the
source temperature was set to 325 °C. Figures 2–5 show the effect of bake out. The hydrogen gas desorbs the
contamination off the entire flow path, and the reactive hydrogen species formed in the ion source clean it out. If water is
present in the gas lines, a m/z of 19 is seen. This is due to protonation of water (M+1). Other ions typical of chemical
ionization and protonation are also seen, m/z 29 and m/z 41 (Figure 2). Elevated levels of low mass hydrocarbons are
observed in the calibration gas spectrum (Figure 4). These all are reduced after the one-hour bake out.
as cause more and more laboratories to
GC methods utilizing FID, TCD, ECD,
especially complex and regulated ones,
to the changes in chromatographic
reactivity brings about chemical
e of helium.
FIGURE 8. Improvement of Peak S
critical pair of benzo[g&h]fluorant
RT: 11.87 - 13.34
12.29
100
12.50
90
H
80
Relative Abundance
arrier gas
70
60
50
40
30
20
10
0
100
11.88
11.97 12.02
12.11 12.14
12.53 12.56 12.63
12.65
12.34 12.37
12.26
12.72 12.76 12.81
90
H
80
70
60
50
EPA Method 82701 and volatile organic
identification and quantitation of well
The diversity of the analytes in this
en carrier. GC-MS analysis of SVOCs
ermo Scientific™ ISQ™ Series single
Key modifications to both GC and MS
arrier gas. The final, optimized EPA
esolution, and run time.
40
30
20
10
0
11.90 11.94 12.03 12.05 12.09 12.16 12.21 12.25 12.27
11.9
FIGURE 2. Air/water spectrum before bake out.
12.0
12.1
12.2
12.72
12.37 12.42 12.46 12.52 12.54
12.3
12.4
12.5
12.6
Time (min)
12.7
12.75 12.8
12.8
FIGURE 3. Air/water spectrum after bake out.
Linearity
m/z 18
m/z 28
m/z 19
m/z 29
formance mix containing
ation of 50 ppm. A calibration curve was
m. For EPA Method 524, a 5 mL volume
Trap Sample Concentrator, OI
hod 525, a 1 L volume of water was
m/z 19
m/z 28
FIGURE 4. Cal Gas (FC-43) spectrum before bake out.
dule was used in the split mode. A one
TG-5MS capillary column (30 m × 0.25
er ID (20 m × 0.18 mm × 0.36 µm film).
njection of gases purged from water
m × 0.18 mm × 1.0 µm film).
A linearity study was performed in t
results are shown in Figures 9 and
than hydrogen but still met the crite
m/z 18
m/z 29
FIGURE 9. Comparison of linea
R2 fit with hydrogen).
FIGURE 5. Cal Gas (FC-43) spectrum after bake out.
strument was preconditioned by baking
nt turned on for one hour.
FIGURE 10. Typical linearity plo
cessed using either Thermo Scientific™
software was configured for direct target
1.
ier gas.
Selecting the Appropriate Column Dimensions and Inlet Pressure
NL:
5.35E8
TIC MS
level8
Due to the lower viscosity of hydrogen carrier gas compared to helium, a lower head pressure is required to obtain 1 mL/
min of column flow rate. By reducing the ID of the column, the pressure may be set to a usable level (Figure 6 ). Also note
the reduction in the vapor volume of methylene chloride at higher pressures (Figure 7).
FIGURE 6. Comparison of inlet pressure for helium and hydrogen for a 0.25 mm and 0.18 mm ID column.
10.24
A linearity study was performed in
results for the PAHs is shown in F
range of concentration from 0.4 to
8.98 9.19
12.35
10.27
11.19
FIGURE 11. Typical linearity of
.41
11.16
Compound
11.44
9.76
9.45
11.72
10.79
8.84
12.55
9.97
FIGURE 7. Methylene Chloride solvent tailing at low vs. high inlet pressures.
RT: 0.000 - 13.008
9
10
12.17
11
12
8.596
90
12.70
80
13
Relative Abundance
10.54
NL:
2.12E8
TIC MS
level1
7.031
100
8.48
5.795
4.039
8 psi
9.808
70
60
50
3.016
40
30
1.368
20
10
2.002
3.281
6.358
4.698 5.057
7.075 7.874
0
100
8.953 9.423
10.099
11.114 11.520
12.801
NL:
1.55E8
TIC MS
1ng
8.309
6.802
90
80
9.338
70
13 psi
5.430
3.730
60
50
2.719
40
30
6.1
2-methylnaphthalene
8.7
1-methylnaphthalene
7.7
acenaphthylene
8.5
acenaphthene
8.5
flourene
8.5
phenanthene
3.8
anthracene
7.0
pyrene
3.6
acenaphthene-d10
4.6
chrysene-d12
9.7
Sensitivity
The sensitivity of the EPA Method
The average Instrument Detection
Figure 12 shows most of the IDLs
Thermo Scientific Poster Note • EAS2013_PN10360_E 11/13S 3
20
10
1.079 1.526
0
0
1
2.681
2
3.000
3
4.367 4.721
4
5
6.035
6.849 7.633
6
7
Time (min)
9.036
8
9
10.411 10.742 11.648 12.000
9.577
10
11
12
13
%RSD
naphthalene
Compound
9.76
9.45
11.72
10.79
8.84
naphthalene
12.55
2-methylnaphthalene
9.97
1-methylnaphthalene
FIGURE 7. Methylene Chloride solvent tailing at low vs. high inlet pressures.
RT: 0.000 - 13.008
s and SVOCs
8.48
9
10
12.17
11
8.596
90
12.70
12
80
13
acenaphthene
NL:
2.12E8
TIC MS
level1
7.031
100
flourene
5.795
4.039
phenanthene
8 psi
9.808
70
Relative Abundance
8
10.54
acenaphthylene
60
anthracene
50
3.016
pyrene
40
30
1.368
acenaphthene-d10
20
10
Texas, USA
2.002
3.281
6.358
4.698 5.057
7.075 7.874
0
100
8.953 9.423
11.114 11.520
10.099
NL:
1.55E8
TIC MS
1ng
8.309
6.802
90
chrysene-d12
12.801
80
Sensitivity
9.338
70
13 psi
5.430
3.730
60
The sensitivity of the EPA M
The average Instrument De
Figure 12 shows most of th
50
2.719
40
30
20
10
1.079 1.526
0
0
1
2.681
2
3.000
3
6.035
4.367 4.721
4
5
6.849 7.633
6
9.036
7
8
10.411 10.742 11.648 12.000
9.577
9
10
11
12
13
Time (min)
FIGURE 12.
Peak Shape and Resolution
FIGURE 8. Improvement of Peak Shape for Indeno[1,2,3-cd]pyrene & benzo[g,h,i]perylene and separation of the
critical pair of benzo[g&h]fluoranthenes.
RT: 11.87 - 13.34
NL:
5.23E6
m/z=
275.50276.50
MS level5
12.29
100
12.50
90
Hydrogen
80
70
Helium
60
50
Hydrogen
40
30
20
RT: 10.26 - 10.43
10
0
100
100
11.88
11.97 12.02
12.11 12.14
12.53 12.56 12.63
12.65
12.34 12.37
12.26
12.72 12.76 12.81
90
12.87
12.93
13.01 13.06 13.12 13.17
Helium
80
NL:
7.26E6
m/z=
275.50276.50
MS level5
90
60
50
95
90
85
80
75
75
70
70
50
45
55
50
45
40
30
25
25
20
60
35
35
30
30
11.11
65
60
55
40
40
NL:
6.19E6
m/z=
251.50252.50
MS level5
11.14
100
85
80
65
Relative Abundance
70
NL:
1.19E7
m/z=
251.50252.50
MS level5
10.36
10.33
95
13.26
13.23
RT: 11.06 - 11.20
Relative Abundance
Relative Abundance
s required. If using a hydrogen generator,
d 1/8 in. stainless steel tubing. If a cylinder
s. The hydrogen kit is installed in the mass
gen carrier is set to 4 mL/min. The filament
en flow is reduced to 1 mL/min, and the
The hydrogen gas desorbs the
in the ion source clean it out. If water is
(M+1). Other ions typical of chemical
d levels of low mass hydrocarbons are
the one-hour bake out.
The advantage of hydrogen carrier gas is that higher than helium linear velocities can be used without sacrificing resolution. By
spending less time in the stationary phase, the late eluting polynuclear aromatic hydrocarbons (PAHs) come out with a
narrower peak width, and the critical pair of benzo[g&h]flouranthenes was easily separated (Figure 8).
20
20
15
15
10
0
10
10
11.90 11.94 12.03 12.05 12.09 12.16 12.21 12.25 12.27
11.9
12.0
12.1
12.2
12.3
12.72
12.37 12.42 12.46 12.52 12.54
12.4
12.5
12.6
Time (min)
12.7
12.75 12.84 12.87 12.94 12.98 13.03
12.8
12.9
13.0
5
13.13
13.1
5
13.2
13.3
0
10.42
10.26
10.26
10.27
10.28
10.29
10.30
10.31
10.32
10.33
10.34
10.35
Time (min)
10.36
10.37
10.38
10.39
10.40
10.41
0
11.06
11.07
11.07
11.16
11.08
11.08
11.09
11.10
11.11
10.42
11.12
11.13
Time (min)
11.14
11.15
11.16
11.17
11.17
11.19
11.18
11.20
11.19
Instrument de
IDL was 0.07
level as 200
/water spectrum after bake out.
Linearity
A linearity study was performed in the range of concentration from 1 to 200 ppm in CH2Cl2 for EPA Method 8270. The
results are shown in Figures 9 and 10 below. Helium carrier gas gave lower relative percent standard deviations (%RSD)
than hydrogen but still met the criteria for the method. A few compounds required the fit of least squares (R2 = > 0.99).
m/z 18
m/z 28
FIGURE 13.
RT: 0.80 - 1.81 SM: 7B
100
50
Compounds:
≤ 0.99
•  nitrophenols
•  nitroanilines
•  dinitrophenols
•  4,6-dinityrophenol-2-methylphenol
•  t richlorophenols
•  dinitrotoluenes
•  hexachlorocyclopentadiene
•  t ribromophenol
•  pentachlorophenol
•  butylbenzylphthalate
•  di-n-octylphthalate
•  bis(2 ethylhexyl)phthalate
0
100
R2
al Gas (FC-43) spectrum after bake out.
50
0
Relative Abundance
m/z 19
m/z 29
FIGURE 9. Comparison of linearity with helium and hydrogen carrier (the compounds on the insert required
R2 fit with hydrogen).
100
50
0
100
50
0
100
50
0
100
50
0
0.80
FIGURE 10. Typical linearity plots with hydrogen carrier gas.
0.85
Robustness
The stability
robustness s
samples also
the internal s
All check sta
FIGURE 14.
head pressure is required to obtain 1 mL/
set to a usable level (Figure 6 ). Also note
ure 7).
5 mm and 0.18 mm ID column.
A linearity study was performed in the range of concentration from 0.05 to 10 ppm for EPA Method 525. An excerpt of
in theforGC-MS
Analysis
of VOCs
and11.
SVOCs
4 From Helium to Hydrogen: Case Study
results
the PAHs
is shown
in Figure
Similarly, for EPA Method 524, a linearity study was performed in the
range of concentration from 0.4 to 200 ppb.
(Figure 6 ). Also note
ID column.
A linearity study was performed in the range of concentration from 0.05 to 10 ppm for EPA Method 525. An excerpt of
results for the PAHs is shown in Figure 11. Similarly, for EPA Method 524, a linearity study was performed in the
range of concentration from 0.4 to 200 ppb.
FIGURE 11. Typical linearity of PAHs in EPA Method 525 with hydrogen carrier gas.
Compound
%RSD
Compound
%RSD
naphthalene
6.1
flouranthene
6.7
2-methylnaphthalene
8.7
benzo(a)anthracene
8.2
1-methylnaphthalene
7.7
chrysene
5.9
acenaphthylene
8.5
benzo(b)fluoranthene
8.6
100
acenaphthene
8.5
benzo(k)fluoranthene
9.2
90
80
FIGURE 15. TIC 5 % diesel sam
RT: 0.00 - 13.26
8.5
benzo(a)pyrene
7.8
phenanthene
3.8
indeno(1,2,3,c,d)pyrene
5.1
anthracene
7.0
dibenz(a,h)anthracene
5.4
pyrene
3.6
benzo(g,h,i)perylene
6.0
acenaphthene-d10
4.6
phenanthene-d10
4.5
chrysene-d12
9.7
perylene-d12
7.4
4.55
85
3.43
5.0
4.01
75
70
65
Relative Abundance
flourene
95
60
55
50
45
40
35
4.92
30
25
3.75
20
4.35
2.80 3.21
15
10
5
Sensitivity
3.19
2.63
1.70
1.96 2.15
2.57
0
0
1
2
3
4
5
The sensitivity of the EPA Method 8270 using hydrogen carrier was within a factor of two to that achieved with helium.
The average Instrument Detection Limit (IDL) with helium was 0.08 ppm and 0.15 ppm with hydrogen. The chart in
Figure 12 shows most of the IDLs are around 0.1 ppm. Replicate injections of the standard were made at 1 ppm.
FIGURE 12. EPA Method 8270 Instrument Detection Limits (ppm) Average = 0.15 ppm.
FIGURE 16. Stability of internal standard are
ithout sacrificing resolution. By
PAHs) come out with a
ure 8).
and separation of the
Butylbenzyl phthalate
Di-n-octylphthalate
Hydrogen
Bis-2-chloroisopropylether
NL:
6.19E6
m/z=
251.50252.50
MS level5
11.14
11.11
11.16
11.10
11.11
11.12
11.13
Time (min)
11.14
11.15
11.16
11.17
11.17
11.19
11.18
11.20
11.19
Instrument detection limits for EPA Method 524 were determined by running replicate injections at 0.4 ppb. The average
IDL was 0.074 ppb (74 ppt) vs. 0.048 ppb (48 ppt) with helium. Excellent sensitivity for the first six gases, even at as low
level as 200 ppt, was obtained (Figure 13).
EPA Method 8270. The
andard deviations (%RSD)
t squares (R2 = > 0.99).
RT: 0.80 - 1.81 SM: 7B
dichlorodifluoromethane
RT: 0.93
AA: 9279
BP: 85
0
pentadiene
ol
late
te
phthalate
RT: 1.04
AA: 47618
BP: 50
100
≤ 0.99
0
chloromethane
RT: 1.09
AA: 19284
BP: 62
100
vinylchloride
RT: 1.29
AA: 21231
BP: 94
100
bromomethane
RT: 1.38
AA: 14294
BP: 64
RT: 1.08
AA: 5325
BP: 64
100
50
0
RT: 1.47
AA: 16876
BP: 101
100
50
0
0.80
0.85
0.90
0.95
1.00
1.05
1.10
1.15
1.20
1.25
1.30
Time (min)
1.35
1.40
90
1.45
1.50
1.55
1.60
1.65
1.70
1.75
3.85
80
4.56
70
6.26
5.18
60
3.34
40
30
3.88
4.26
7
6.97
5.65
50
4.61
7.01
3.31
20
1.80
10
2.25 2.98
2.51
0
100
NL: 1.11E4
m/z= 101-102 F: {0,0}
+ c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
trichlorofuoromethane
6.83
100
NL: 9.91E3
m/z= 64-65 F: {0,0} +
c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
chloroethane
12/5/2012 2:04:03 PM
RT: 0.00 - 20.01
NL: 1.30E4
m/z= 94-95 F: {0,0} +
c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
50
0
C:\chem\...\level8.d\level8
NL: 1.51E4
m/z= 62-63 F: {0,0} +
c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
50
0
FIGURE 17. Comparison of run time with hyd
NL: 2.67E4
m/z= 50-51 F: {0,0} +
c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
50
Relative Abundance
ol-2-methylphenol
NL: 7.88E3
m/z= 85-86 F: {0,0} +
c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
50
n the insert required
nds:
The run time for EPA Method 8270 was reduce
x 0.36 µm) and hydrogen carrier gas. The more
mm x 30 m x 0.5µm. (Figure 16).
FIGURE 13. EPA Method 524 first six gases at 200 ppt with hydrogen carrier gas.
100
R2
Run Time
Relative Abundance
11.09
7
6.63 7.46
90
6.14
80
70
1.80
60
5.34
Robustness and Ion Ratio Stability
7.22
5.36
6.04
50
6.76
40
The stability of ion ratios for DFTPP and BFB was studied. The values were very stable (Figure 14). Next, a
robustness study was run for EPA Method 8270 by injecting 30 of 5% diesel samples in methylene chloride. The
samples also contained 40 ppm of the internal standards. The diesel sample TIC is shown in Figure 15. A chart with
the internal standards plotted is shown in Figure 16. A check standard was run after each set of 10 diesel samples.
All check standards met the QC criteria for the method.
FIGURE 14. Ion ratio stability for DFTPP (left) and BFB (right).
m/z Criteria/Batch 01 02
30
3.84
20
2.82
10
2.65
0
0
1
2
3.24
3
4.17
4
5
Thermo Scientific Poster Note • EAS2013_PN10360_E 11/13S 5
03
04 05 06 07 08 09
10
11
6
7
di-n-octylphthalate
bis(2 ethylhexyl)phthalate
0
RT: 1.47
AA: 16876
BP: 101
100
50
0
0.80
0.85
0.90
0.95
1.00
1.05
1.10
1.15
1.20
1.25
1.30
Time (min)
1.35
1.40
1.45
1.50
1.55
1.60
1.65
1.70
1.75
100
NL: 1.11E4
m/z= 101-102 F: {0,0}
+ c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
trichlorofuoromethane
90
80
70
1.80
60
50
Robustness and Ion Ratio Stability
40
The stability of ion ratios for DFTPP and BFB was studied. The values were very stable (Figure 14). Next, a
robustness study was run for EPA Method 8270 by injecting 30 of 5% diesel samples in methylene chloride. The
samples also contained 40 ppm of the internal standards. The diesel sample TIC is shown in Figure 15. A chart with
the internal standards plotted is shown in Figure 16. A check standard was run after each set of 10 diesel samples.
All check standards met the QC criteria for the method.
30
3.84
20
2.82
10
2.65
0
0
1
2
3.24
3
4.17
4
FIGURE 14. Ion ratio stability for DFTPP (left) and BFB (right).
m/z Criteria/Batch 01 02
03
04 05 06 07 08 09
10
11
50
15-40%
28 26
26
24 27 26 25 26 28
25
25
75
>30%
52 51
48
48 51 52 49 48 48
50
53
95
100%
96
ppm for EPA Method 525. An excerpt of
nearity study was performed in the
5-9%
8.0 7.3 7.9 7.7 8.2 7.2 7.7 7.4 7.8 7.5 7.7
173 < 2% of 174 0.4 0.6 0.7 1.5 0.4 0.4 0.8 0.7 0.5 1.1 0.3
174
>50%
76 75
69
69 75 70 72 72 71
74
72
175 5-9% of 174 7.3 7.4 7.4 5.9 7.6 8.5 6.4 7.7 6.8 6.4 6.7
carrier gas.
95-101% of
96 95 100 96 93 96 98 95 96 101 96
174
176
177 5-9% of 176 5.1 6.3 6.6 5.2 6.4 6 5.1 5.5 6.6 6.5 6.0
FIGURE 15. TIC 5 % diesel sample.
RT: 0.00 - 13.26
NL:
6.22E8
TIC MS
diesel5
7.76
100
6.21
6.77
8.18
95
7.30
90
5.65
3.43
7.31
5.09
4.01
75
70
8.92
Relative Abundance
65
55
7.79
50
9.25
7.01
5.97
45
5.50
5.29
35
9.56
4.92
7.47
25
3.75
20
9.85
4.35
2.63
5
1.70
1.96 2.15
3.19
0
1
2
10.68
3
4
5
6
= 0.15 ppm.
7
8
9
10
12
3. 
EPA Method 525.2, D
capillary column gas c
© 2013 Thermo Fisher Scientific
This information is not intended t
Run Time
The run time for EPA Method 8270 was reduced by using a smaller ID column (TraceGOLD TG-5MS 0.18 mm x 20 m
x 0.36 µm) and hydrogen carrier gas. The more commonly used column with helium is the TraceGOLD TG-5MS 0.25
mm x 30 m x 0.5µm. (Figure 16).
ier gas.
NL: 7.88E3
m/z= 85-86 F: {0,0} +
c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
FIGURE 17. Comparison of run time with hydrogen and helium at 1 mL/min.
C:\chem\...\level8.d\level8
NL: 2.67E4
m/z= 50-51 F: {0,0} +
c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
12/5/2012 2:04:03 PM
RT: 0.00 - 20.01
Hydrogen 1 mL/min
(TraceGOLD TG-5MS 0.18 mm x 20 m, 0.36 µm)
6.83
100
90
3.85
Relative Abundance
80
6.26
5.18
60
3.34
40
30
3.88
4.26
9.19
11.19
8.06
8.41
4.61
9.76
7.01
1.80
11.44
12.55
2.25 2.98
2.51
12.70
0
100
7.58
6.63 7.46
90
8.06
6.14
80
1.80
50
11.16
10.79
8.84
3.31
20
60
12.35
10.27
7.64
6.97
5.65
50
10
NL:
5.35E8
TIC MS
level8
10.24
7.90 8.98
4.56
70
8.80
9.44
10.65 10.71
8.59
9.01
in the GC-MS Analysis of VOCs and SVOCs
6 From Helium to Hydrogen: Case Study
70
1.75
EPA Method 524.2, M
chromatography/mass
13
plicate injections at 0.4 ppb. The average
itivity for the first six gases, even at as low
1.70
2. 
11.62 12.01 12.80 13.23
FIGURE 16. Stability of internal standard areas during injection of 5% diesel.
1.65
EPA Method 8270D, S
MS) REV. 4, 2007, En
11.47
10.95
11
e
1.60
1. 
Time (min)
actor of two to that achieved with helium.
0.15 ppm with hydrogen. The chart in
f the standard were made at 1 ppm.
1.55
Shorter run time
10.24
2.57
0
trichlorofuoromethane
Good ion ratio stability
 
10.13
10
NL: 1.11E4
m/z= 101-102 F: {0,0}
+ c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
Sensitivity was within
 
2.80 3.21
15
chloroethane
Linearity met the crite
 
6.55
30
NL: 9.91E3
m/z= 64-65 F: {0,0} +
c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
Good resolution and i
 
60
40
ethane
 
References
8.57
80
NL: 1.30E4
m/z= 94-95 F: {0,0} +
c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
GC-MS analysis of SVOCs wa
an ISQ single quadrupole mas
MS hardware and methods ne
optimized EPA Method 8270 w
time. The ISQ Series MS was
were:
4.55
85
NL: 1.51E4
m/z= 62-63 F: {0,0} +
c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
Conclusion
5.34
9.56
6.04
NL:
1.12E8
TIC MS
03091102_
110309112
925
13.21 13.84
13.15
11.27
14.62
13.96
15.37
18.08
12.57
10.02
6.76
12.43
9.61
7.22
5.36
10.89
12.13
15.33
15.85
g replicate injections at 0.4 ppb. The average
ensitivity for the first six gases, even at as low
Run Time
The run time for EPA Method 8270 was reduced by using a smaller ID column (TraceGOLD TG-5MS 0.18 mm x 20 m
x 0.36 µm) and hydrogen carrier gas. The more commonly used column with helium is the TraceGOLD TG-5MS 0.25
mm x 30 m x 0.5µm. (Figure 16).
arrier gas.
NL: 7.88E3
m/z= 85-86 F: {0,0} +
c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
FIGURE 17. Comparison of run time with hydrogen and helium at 1 mL/min.
C:\chem\...\level8.d\level8
NL: 2.67E4
m/z= 50-51 F: {0,0} +
c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
90
47
6876
01
1.50
1.55
Relative Abundance
NL: 9.91E3
m/z= 64-65 F: {0,0} +
c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
1.60
1.65
1.70
1.75
6.26
5.18
60
3.88
4.26
3.34
40
30
9.19
12.35
10.27
7.64
6.97
5.65
50
11.19
8.06
8.41
4.61
9.76
7.01
11.16
11.44
10.79
8.84
12.55
3.31
1.80
10
2.25 2.98
2.51
12.70
0
100
8.80
7.58
6.63 7.46
90
9.44
10.65 10.71
8.06
6.14
80
8.59
9.01
9.56
10.89
12.13
12.43
60
5.34
14.62
13.15
13.96
11.27
15.37
6.04
50
18.08
7.22
5.36
NL:
1.12E8
TIC MS
03091102_
110309112
925
13.21 13.84
9.61
70
1.80
12.57
15.33
10.02
15.85
6.76
18.71
40
e very stable (Figure 14). Next, a
l samples in methylene chloride. The
le TIC is shown in Figure 15. A chart with
run after each set of 10 diesel samples.
NL:
5.35E8
TIC MS
level8
10.24
7.90 8.98
4.56
70
20
NL: 1.11E4
m/z= 101-102 F: {0,0}
+ c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
trichlorofuoromethane
3.85
80
NL: 1.30E4
m/z= 94-95 F: {0,0} +
c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
chloroethane
Hydrogen 1 mL/min
(TraceGOLD TG-5MS 0.18 mm x 20 m, 0.36 µm)
6.83
100
NL: 1.51E4
m/z= 62-63 F: {0,0} +
c EI Full ms
[47.00-300.00] MS
ICIS 200pptC
omethane
12/5/2012 2:04:03 PM
RT: 0.00 - 20.01
30
3.84
20
15.92
2.82
10
2.65
0
0
1
2
3.24
3
11.32
4.17
4
5
6
7
8
9
10
Time (min)
11
12
18.91
16.42 17.11
13
14
15
16
17
18
19
20
Helium 1 mL/min
(TraceGOLD TG-5MS 0.25 mm x 30 m, 0.5 µm)
/Batch 01 02
03
04 05 06 07 08 09
10
11
0%
28 26
26
24 27 26 25 26 28
25
25
%
52 51
48
48 51 52 49 48 48
50
53
100%
%
8.0 7.3 7.9 7.7 8.2 7.2 7.7 7.4 7.8 7.5 7.7
of 174 0.4 0.6 0.7 1.5 0.4 0.4 0.8 0.7 0.5 1.1 0.3
%
76 75
69
69 75 70 72 72 71
74
72
of 174 7.3 7.4 7.4 5.9 7.6 8.5 6.4 7.7 6.8 6.4 6.7
1% of
96 95 100 96 93 96 98 95 96 101 96
4
of 176 5.1 6.3 6.6 5.2 6.4 6 5.1 5.5 6.6 6.5 6.0
NL:
6.22E8
TIC MS
diesel5
Conclusion
GC-MS analysis of SVOCs was performed in accordance with EPA Method 8270 on a TRACE 1310 GC coupled with
an ISQ single quadrupole mass spectrometer utilizing hydrogen carrier gases. Key modifications to both the GC and
MS hardware and methods necessary for successful migration to hydrogen carrier were performed. The final,
optimized EPA Method 8270 was fully migrated to hydrogen carrier gas with improved peak shape, resolution, and run
time. The ISQ Series MS was stable and maintained good ion ratio stability after injecting 5% diesel samples. Results
were:
 
Good resolution and improved peak shape
 
Linearity met the criteria of the method
 
Sensitivity was within a factor of 2 of that obtained with helium carrier gas
 
Good ion ratio stability and robustness
 
Shorter run time
References
1. 
EPA Method 8270D, Semi-volatile Organic Compounds by Gas Chromatography/Mass Spectrometry (GC/
MS) REV. 4, 2007, Environmental Protection Agency.
2. 
EPA Method 524.2, Measurement of purgeable organic compounds in water by capillary column gas
chromatography/mass spectrometry. Rev. 4.1, 1995.
3. 
EPA Method 525.2, Determination of organic compounds in drinking water by liquid-solid extraction and
capillary column gas chromatography/mass spectrometry. Rev.2, 1995.
13.23
13
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