Progress on standards for NMHC,
terpenes and oxygenated VOCs
Marivon Corbel
4th GAW Expert Workshop on Volatile Organic Compounds
11-12th September 2012, York, United Kingdom
1. Terpenes
Terpenes
 1300 Tg(C)yr-1 reactive biogenic emissions
10x larger than anthropogenic emissions
 Target class of compound for Global Atmosphere
Watch (GAW)
Monoterpenes
Ambient
Mixing Ratio
(ppb)
Desired
Calibration
Concentration
(ppb)
Desired
Gas
Cylinder
Uncertainty
0.001 – 1
0.5
3%
Terpenes at NPL since 2007





2007 Terpene mixture with 2 terpenes (TP704)
2009 Terpene mixture with 18 components (TP910)
2009 Terpene mixture with 17 components (TP915)
2010 Terpene mixture with 17 components (TP1003)
2010 Terpene mixture with 17 components in NPL
proprietary cylinder (TP1005)
 2011 Terpene mixture with 4 components (TP1120)
 2012 Terpene mixture with 4 components (TP1203)
Stability issues with 17 & 18
component mixtures
32,000
µV
TP907_7.DATA
28,000
26,000
24,000
400 µV
TP907_7.DATA
96.451
sabinene
30,000
350
300
0.765
22,000
250
0.286
0.316
0.102
0.016
0
8,000
0.137
0.265
50
10,000
0.171
100
12,000
0.085
150
14,000
0.466
16,000
0.355
200
18,000
0.222
 Sabinene decomposition
20,000
-50
6,000
RT [min]
4,000
4.8
5
5.2
5.4
5.6
5.8
6
6.2
6.4
6.6
6.8
7
7.2
7.4
7.6
7.8
8
8.2
8.4
8.6
8.8
9
9.2
9.4
9.6
9.8
2,000
RT [min]
0
 Sabinene degradation in SPT
 Reduction in various compounds:
4.6
camphor
myrcene
4.8
5
5.2
5.4
5.6
5.8
6
6.2
6.4
cis-ocimene
6.6
6.8
7
7.2
7.4
7.6
7.8
8
8.2
8.4
8.6
8.8
9
p-cymene
9.2
9.4
9.6
Terpene Family Tree (Mark IV)
limonene
α-pinene
1,8-cineole
Δ3-carene
100 ppb
2 ppb
5 ppm
2011
TP1120
2012
TP1203
Chromatogram of 2 ppb TP1120
α-pinene
limonene
Δ3-carene
1,8-cineole
Stability data for TP1120 NPL
in-house 2011 2ppb Terpene
Standard
Measured against mixture freshly diluted from
100 ppb standard
Calibrated concentration (ppb)
2.5
2
1.5
1
0.5
0
+/- a-pinene
gravimetric
+3-carene
t = 14 months
limonene
t = 15 months
1,8-cineole
t = 17 months
Collaboration with NIST
July
August
November
Cylinder sent to NIST
for analysis
NIST sent 5 ppb
cylinder to NPL
NPL to send
cylinders to NIST
Jan
2013
June
2012
October
June
August
Reanalysis of NPL
cylinder
NPL made 2 ppb
Terpene to send
to NIST
Cylinder returned to
NPL for reanalysis
Reanalysis of NIST
cylinder at NPL
Bi-lateral comparison results
NPL standard
3
Concentration (ppb)
2.5
NPL Grav ppb
2
NIST results
ppb
1.5
1
0.5
0
+/- a-pinene
+3-carene
limonene
1,8-cineole
Bi-lateral comparison results
NIST standard
9.00
Concentration (ppb)
8.00
7.00
6.00
5.00
NIST Grav ppb
4.00
NPL results ppb
3.00
2.00
1.00
0.00
+/- a-pinene
+3-carene
limonene
1,8-cineole
Bi-lateral comparison with NIST
Concentration (ppb)
3
2.5
2
NPL Grav ppb
1.5
1
NIST results
ppb
0.5
0
Concentration (ppb)
+/- a-pinene
+3-carene
limonene
1,8-cineole
9.00
8.00
7.00
NIST Grav
ppb
6.00
5.00
4.00
3.00
NPL results
ppb
2.00
1.00
0.00
+/- a-pinene
+3-carene
limonene
1,8-cineole
Moving Forward…
 4 component terpene mixture available
 Continuation of 2007 terpenes stability analysis
 Continue stability trials of all in-house mixtures
 Assess decay of 1,8-cineole in 4 component mixtures
 Conclusions from NIST-NPL analyses
2. NMHC
Non-Methane Hydrocarbons
(NMHCs)
 Reactive trace gases
 Found in ratios of a few ppb or below 1 ppb
 Generally C1 to C8 alkanes, alkenes, alkyne and
aromatics
 Influence the oxidising capacity of the atmosphere
 1300 Tg(C)yr-1 reactive biogenic emissions
 140 Tg(C) yr-1 reactive anthropogenic emissions
NMHCs at NPL
Date
Mixtures available
1988
11 components
1990
25 components
1992
27 components
1993
26 components
1997
30 components
2005
Ozone Precursor (O3P) VOC mixtures containing all of
the VOCs listed in the EU directive (2002/3/EC)
2008
O3P MkII
2010
30 component EU Directive ozone precursor gas
standard is recognised by the World Meteorological
Organisation (WMO) as their primary standard.
2012
O3P MkIII
Route to O3P MKIII
12,3-TMB
10 ppm
n-octane
n-heptane
i-octane
n-hexane
i-hexane
100 ppm
1,2,4-TMB
10 ppm
1,3-butadiene
propane
propene
acetylene
ethane
ethene
100 ppm
trans-2-pentene
n-pentane
isoprene
1-pentene
2-methylbutane
100 ppm
cis-2-butene
trans-2-butene
n-butane
1-butene
i-butane
100 ppm
1,3,5-TMB
10 ppm
BTEX
10 ppm
200 ppb
10 ppm
4 ppb
OP1112
OP1115
OP1112 verification using O3P
MKII standard
10.00%
8.00%
6.00%
% difference
4.00%
2.00%
0.00%
-2.00%
-4.00%
-6.00%
-8.00%
-10.00%
1
2
3
4
5
Number of measurements
6
ethane
ethene
propane
propene
acetylene
i-butane
n-butane
trans-2-butene
1-butene
cis-2-butene
2-methyl butane
n-pentane
1,3-butadiene
trans-2-pentene
1-pentene
2-methyl pentane
n-hexane
isoprene
n-heptane
benzene
2,2,4-trimethyl pentane
n-octane
toluene
ethyl-benzene
m+p-xylene
o-xylene
1,3,5-trimethyl benzene
1,2,4-trimethyl benzene
1,2,3-trimethyl benzene
OP1115 verification using O3P
MKII standard
10.00%
8.00%
6.00%
% difference
4.00%
2.00%
0.00%
-2.00%
-4.00%
-6.00%
-8.00%
-10.00%
1
2
Number of measurements
3
ethane
ethene
propane
propene
acetylene
i-butane
n-butane
trans-2-butene
1-butene
cis-2-butene
2-methyl butane
n-pentane
1,3-butadiene
trans-2-pentene
1-pentene
2-methyl pentane
n-hexane
isoprene
n-heptane
benzene
2,2,4-trimethyl pentane
n-octane
toluene
ethyl-benzene
m+p-xylene
o-xylene
1,3,5-trimethyl benzene
1,2,4-trimethyl benzene
1,2,3-trimethyl benzene
Moving Forward…
 Continuation of O3P stability analysis
 Assess the difference in acetylene concentration
between the O3P standards MKII and the O3P
standards MKIII
 Resolve analytical issues encountered with acetylene
3. Oxygenated VOCS
Oxygenated Volatile Organic
Compounds
 From direct-primary or indirect-secondary biogenic or
anthropogenic sources
 Short chained carbonyls
acetone
methanol
ethanol
Estimated lifetime in
the troposphere:
15 days
Estimated lifetime in
the atmosphere:
10 days
Estimated lifetime in
the atmosphere:
3.5 days
mixing ratios range
from 0.3 to 80 ppbv
2nd most abundant gas
in the atmosphere
after methane
0.2 to 200 ppbv
mixing ratios below
10 ppbv
Oxygenated VOC Standards
Family Tree
VOC8
5 ppm
Sept-09
VOC9
50 ppm
Sept-09
VOC10
5 ppm
Sept-09
A373
5 ppm
June-10
A395
5 ppm
May-12
A396
50 ppm
May-12
A386
5 ppm
Oct-11
A394
5 ppm
May-12
stability study of 5 ppm oxy-VOCs
 Standards prepared in Spectraseal cylinders
 Preparation uncertainties:
• methanol
0.1%
• ethanol
0.1%
• acetone
0.08%
• n-hexane
0.06%
Gravimetric values (µmol/mol)
Date
Aug-09
Aug-09
May-10
Oct-11
May-12
May-12
VOC 8
VOC 10
A373
A386
A394
A395
methanol
5.040
5.042
5.043
5.040
4.985
4.987
ethanol
5.041
5.043
5.044
5.041
5.073
5.076
acetone
4.868
4.870
4.870
4.868
4.989
4.991
n-hexane
5.062
5.064
5.065
5.062
4.908
4.911
Stability data for VOC8 and
VOC10 5 ppm standards
• % Difference between calculated concentration and
gravimetric data
• Measured against mixture freshly diluted from 50
ppm standard
0.5
0.4
0.3
% difference
0.2
VOC 8 after 52
months
0.1
0
methanol
-0.1
-0.2
-0.3
-0.4
-0.5
ethanol
acetone
n-hexane
VOC 10 after 53
months
Verification of 5 ppm standards
A394 and A395 using A386
% Difference between calculated concentration and
gravimetric data
2.00%
% difference
1.50%
1.00%
A394
0.50%
A395
0.00%
Methanol
-0.50%
-1.00%
-1.50%
Ethanol
Acetone
n-hexane
VSL analysis of 5 ppm NPL
standard A394
6
Concentration (ppm)
5
4
NPL Grav
ppm
3
2
VSL Results
ppm
1
0
Methanol
Ethanol
Acetone
n-hexane
Moving Forward…
 Stable 5 ppm oxygenated-VOC standards available
containing methanol, ethanol, acetone and n-hexane
 Continue stability trials of all in-house mixtures
 Complete tri-lateral comparison with VSL and NIST
Thank you