GUM’s contribution to the International Metrology in Chemistry Programme at the BIPM
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Transcript of GUM’s contribution to the International Metrology in Chemistry Programme at the BIPM
Bureau International des Poids et Mesures
GUM’s contribution to the International Metrology in Chemistry Programme at the BIPM
R. I. Wielgosz (BIPM)
Bureau International des Poids et Mesures
1Bureau International des Poids et Mesures
Bureau International des Poids et Mesures
OUTLINE OF PRESENTATION
• BIPM, International Metrology, National Metrology Institutes
• Visiting Scientist secondment programme to the BIPM
• Standards and comparisons for Atmospheric Composition: Air Quality and Greenhouse Gases
• Conclusions and future outlook
Bureau International des Poids et Mesures
BUREAU INTERNATIONAL DES POIDS ET MESURES
The BIPM is an intergovernmental organization established by the Metre Convention, through which Member States act together on matters related to measurement science and measurement standards.
www.bipm.org
The mission of the BIPM is to ensure and promote the global comparability of measurements, including providing a coherent international system of units for:• Scientific discovery and innovation,• Industrial manufacturing and international trade,• Sustaining the quality of life and the global environment.
BIPM Chemistry Department includes programme on:
International equivalence of gas standards for air quality and climate change monitoring
Coordinating comparisons of gas standards with the National Metrology Institutes and Designated Institutes within the CCQM Gas Analysis Working Group
Bureau International des Poids et Mesures
Visiting Scientists to the BIPM Chemistry Department
J. Norris (NIST) 16 June – 1 Aug 2003M. Sega (INRIM) 5 Sept – 2 Dec 2005T. Ihara (NMIJ) 10 Oct – 10 Nov 2005A. Rakowska (GUM) 31 Jan – 27 Apr 2006Y. Shimitzu (NMIJ) 21 Aug – 15 Sept 2006J. Guardado (CENAM) 30 March – 31 July 2007C. Dazhou (NIM) 27 Aug- 20 Nov 2008G. Ochmann (GUM) 1 Sept – 30 Nov 2008C. Dazhou (NIM) 1 Oct – 4 Dec 2009P. Mitchell (NMIA) 1 July - 30 Sept 2011K. Tworek (GUM) 1 June – 30 Nov 2012S. Lee (KRISS) 1 March – 31 May 2013M. Lee (NIM) 1 May 2013 – 30 November 2015C. Pascal (METAS) 1 March 2014 – 30 July 2015D. Song (NIM) 1 June 2014 – 30 Nov 2014M. Minarro (NPL) 1 Sept 2014 – 30 Nov 2014B. Garrido (INMETRO) 1 Feb 2015 – 31 May 2015
Greenhouse and Air Quality Gases
GASRecent
tropospheric concentration
Carbon dioxide (CO2) 392.6 µmol/molMethane (CH4) 1874 nmol/molNitrous oxide (N2O) 324 nmol/molTropospheric ozone (O3) 34 nmol/mol
Halocarbons (0.003 to 0.5) nmol/mol
Pollutant Concentration Averaging period
Ozone 60 nmol/mol Maximum daily 8 hour mean
Sulphur dioxide (SO2) 120 nmol/mol 1 hour 45 nmol/mol 24 hours
Nitrogen dioxide (NO2) 100 nmol/mol 1 hour 20 nmol/mol 1 year
Carbon monoxide (CO) 8 µmol/mol Maximum daily 8 hour mean
Benzene 1.5 nmol/mol 1 year Fine particles (PM2.5) 25 µg/m3 1 year PM10 50 µg/m3 24 hours
40 µg/m3 1 year Lead (Pb) 0.5 µg/m3 1 year
Air Quality
Greenhouse Gases
2010 WMO-BIPM workshop on “
Measurements Challenges for Global Observation Systems for Climate Change Monitoring
’’Signature of CIPM-MRA by WMO
WMO-BIPM Workshop
http://www.bipm.org/en/events/wmo-bipm_workshop/6Bureau International des Poids et Mesures
Wielgosz R., Calpini B., (Editors), Report on the WMO-BIPM workshop on Measurement Challenges for Global Observation Systems for Climate Change Monitoring: Traceability, Stability and Uncertainty, Rapport BIPM-2010/08, 100 pp
Ozone StandardReferencePhotometer
BAKI titration
Gas Phasetitration
GravimetryNO / NO2
Gas standards
Absorptioncross section
(UV)
Absorptioncross section
(IR)
Opticalmeasurements
of pure O3
PressureVolume
Temperature
GravimetryIodide
standards
Atmospheric Ozone Measurements
(Total Column, Stratospheric) (Surface ozone)
Dobson and BrewerSpectrophotometers
Satellite basedmeasurement
systems
FTIR basedsystems
UV ozonephotometers
Establishing Traceability for Atmospheric Ozone Measurements
BIPM-NIST programme to maintain the comparability of the worldwide network of ozone reference standards
Surface Ozone Standards and Comparisons
NIS
T
ISC
III
ERLA
P
Envi
ronm
ent C
anad
a
MET
AS
SRP1
8
MET
AS
SRP1
4
KR
ISS
LNE
VNIIM FM
I
WM
O/W
CC
-EM
PA
UB
A (A
)
SP
NPL
ND
ENW
UB
A (D
)
NIE
S
CH
MI
CSI
R-N
ML(
1)
NER
I
NIL
U
NM
i-VSL
IMG
C
CSI
R-N
ML
(2)
BIP
M G
PT
NIE
S G
PT
-20
-15
-10
-5
0
5
10
15
20
Deg
ree
of e
quiv
alen
ce (nm
ol/m
ol)
(k=2)
GPT
UV Photometric Methods
2.5% bias relative to UV
method
CCQM-P28 Degrees of Equivalence, Ozone mole fraction:420 nmol/mol
Progress Report (2004-2005)
NO2 primary facility (dynamic preparation)
Ozone reference standard
comparison facility
CCQM-P28BIPM.QM-K1
Ozone (2-1000) nmol/mol
CCQM-P73NO (30-70) µmol/mol
Gas Phase TitrationNO + O3 NO2 + O2
CCQM-K74 (including validation of
spectroscopic methods)
-7.000
-6.000
-5.000
-4.000
-3.000
-2.000
-1.000
0.000
1.000
2.000
3.000
KR
ISS
(M1)
KR
ISS
(M15
)C
SIR
-NM
L (M
2)C
SIR
-NM
L (M
16)
CE
RI (
M3)
CE
RI (
M14
)V
ALC
RM
1 (M
4)V
ALC
RM
2 (M
11)
VA
LCR
M3
(M17
)LN
E (M
5)LN
E (M
19)
SM
U (M
6)S
MU
(M18
)C
EN
AM
(M7)
CE
NA
M (M
20)
VN
IIM (M
8)V
NIIM
(M22
)N
IST
(M9)
NIS
T (M
24)
NM
IA (M
10)
NM
IA (M
23)
IPQ
(M12
)IP
Q (M
25)
NM
i-VS
L (M
13)
NM
i-VS
L (M
21)
NP
L N
IST
NM
i-VS
L B
NM
-LN
E
KR
ISS
N
RLM
* N
RC
CR
M
VN
IIM
OM
H
BN
M-L
NE
N
PL
VN
IIM
NM
i-VS
L G
UM
C
EM
M
ETA
S
CH
MI
FM
I IP
Q
Laboratory (cylinder)
D/ m m
ol/m
ol
CCQM-P73 (LIMAS 11UV analysis) CCQM-K1.c EUROMET-K1.c
4000 3500 3000 2500 2000 1500 1000
0.00
0.05
0.10
0.15
0.20
Abs
orba
nce
Wavenumber / cm -1
GPT Experiment Sequence
0
200
400
600
800
1000
1200
0 50 100 150 200 250 300 350 400
time / minutes
[NO
], [O
3] /
(nm
ol/m
ol)
cycle 1 cycle 2 cycle 3 cycle 4 cycle 5
Nitrogen Monoxide Comparison
NO2
Differences in Reference Methods for Ozone
Consider ozone partial pressure, as decomposition 2O3 -> 3O2 will rapidly occur
3ln( )
2( )Oopt i T
T RL P P Na
Measure O2 and other impurities, as O3 will never be “pure” (max ~99%)
Lopt to be measured by interferometry
Ozone cross-section a measurement challenge
Ozone generator (high voltage discharges)
5 cm absorption cell
Large range pressure gauge
High accuracy pressure gauge (Baratron) for P < 1 mbar
Mass spectrometer
Temperature controlled cryostat
Frequency doubled argon-ion laser with intensity stabilisation
BIPM facility for ozone cross section measurements
• Double walls tube in glass
• Inside/outside electrodes to apply high voltage
• Discharges in oxygen produce ozone
20 kV, 50 kHz
• Entire system inside temperature controlled cryostat
• Ozone trapped in liquid form
• Pumping to remove remaining oxygen
• Slow temperature increase release pure gas-phase
ozone
Liquid ozone trapped at 80 K
Cryogenic Ozone Generator
Michelson interferometer to deduce Lopt in the cell in which the pressure is varied
a01
2n L F
n : index of refraction of air L0 / m : light path length F : number of fringesa / m : laser wavelength
8 2 1 2 1 810 8342.54 2406147(130 ) 15998(38.9 ) 1 10 0.601 0.009721
96095.43 1 0.003661
p T pn
T
Pressure in the cell: 1 bar -> 0.1 mbar -> F fringes on the photodiode -> Path length L0
Edlen formula for the air index of refraction at pressure P and temperature T
Absorption pathlength measurements by interferometry
Typical valuesStarting pressure Pi = 1012 hPa Temperature T = 22.39°CLaser l = 632.991 nm F = 42.37 fringes
Giving Lopt = 4.978 cm, u(Lopt) = 0.012 cm
Fringes signal on photodiode recorded with Labview:
Fringes are counted with Labview as well => most important uncertainty component
Last series of measurements
0 2 4 6 8 104.95
4.96
4.97
4.98
4.99
5.00
5.01
path
leng
th (c
m)
Measurement number
Lopt = 4.978 cm with u(Lopt) = 0.012 cm
Absorption pathlength measurements by interferometry
Absolute measurements of ozone cross-section with the UV-laser
245 250 255 260-1.0
-0.5
0.0
0.5
1.0 This work Gorshelev BDM Burrows
(
bogu
mil) /
10-1
8 cm
2 mol
ecul
e-1
/ nm
Accurate laser measurements of ozone absorption cross-sections in the Hartley band
0.2 0.4 0.6 0.8 1.00.985
0.990
0.995
1.000
x(O
3) / (m
ol m
ol-1)
P (sample) / (mbar) Liquid ozone trapped at 80 K
Cryogenic ozone generator Evaporation-condensation cycles Impurity analysis by RGA & FTIR
Ozone purity better than 99%
BIPM values in agreement with absolute measurements (in pure ozone)
Lowest uncertainty : 0.6%
Accurate laser measurements of ozone absorption cross-sections in the Hartley band.J. Viallon , S. Lee , P. Moussay, K. Tworek , M. Petersen , R.I.WielgoszSubmitted to Atmospheric Measurement Techniques
Bureau International des Poids et Mesures
NO2 standards and comparison (10ppm)CCQM GAWG key comparison on NO2 and Spectroscopic Measurements
The Air Quality Strategy for England, Scotland, Wales and Northern Ireland
Objectives (for 2020) for particulate matter (PM10), nitrogen dioxide (NO2), ozone (O3), and polycyclic aromatic hydrocarbons (PAHs) are unlikely to be achieved, without further measures
BIPM dynamic gas standard facility for NO2
Flow Control System for Rubotherm1. Zero air generator2. Nitrogen Generator3. Nitrogen Cylinders4. molbloc (0-1000) mL/min5. SAES Nitrogen purifier6. Mass flow controller (0-100) mL/min7. Mass flow controller (0-1000) mL/min
Rubotherm System (dynamic gas mixtures)8. Magnetic suspension balance9. NO2 permeation tube
Flow Control System for NO2 Gas Standards10.Mass flow controller (0-1000) mL/min11.Multi position valve (16-ports)
11
waste
waste
10
V
8Flow Control System for Rubotherm
Flow Control System for NO2 Gas Standards
V
P
1
V3
3
2
Rubotherm System
P
P
7
6
4
5
P
P
9
BIPM facility for NO2 Standards
Bureau International des Poids et Mesures
2000 1800 1600 1400 1200 1000
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
H2O
HNO3
NO2 HNO
3
Abs
orba
nce
/Abs
Wavenumber /cm-1
N2O
4
H2O
Infrared absorbance spectrum of a 150 μmol mol−1 NO2/N2 gas mixture generated using the small NO2 permeation device
Quantification of HNO3 without gas standards?
N2O4 negligible impurity at lower concentrations
Purity and quantification of permeating gas: Analysis by FTIR
20Bureau International des Poids et Mesures
xNO2 - NO2 mole fraction;
P - NO2 permeation rate;
Vm - molar volume of nitrogen;
MNO2 - the molar mass of NO2;
qv - total flow of nitrogen;
MHNO3 - the molar mass of NO3; and
xHNO3 - HNO3 mole fraction measured by FTIR.
2
33
2
2NO
HNOHNO
NO
mNO M
xMMqVPx
v
17.82
17.83
17.84
17.85
17.86
17.87
17.88
17.89
17.9
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05/12/200700:00:00
05/12/200712:00:00
06/12/200700:00:00
06/12/200712:00:00
07/12/200700:00:00
07/12/200712:00:00
08/12/200700:00:00
08/12/200712:00:00
09/12/200700:00:00
NO2 Permeation Rate and Impurities
• Resolution: 2 μg;• Stability,3 days: ~ 0.5 μg;
NO2 permeation rate, P, (5000-10000) ng/min u 2 ng/min
FTIR gas facility
Flores E., Idrees F., Moussay P., Viallon J., Wielgosz R., Highly Accurate Nitrogen Dioxide (NO2) in Nitrogen Standards Based on Permeation, Anal. Chem., 2012, 84(23), 10283-10290
HNO3 quantification using MALT
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HNO3
H2O
NO2
0.050
0.080
0.110
0.140
0.170
0.200
0.230
8.0 9.0 10.0 11.0 12.0 13.0BIPM_NO2 Facility XNO2 μmol/mol
MA
LT c
alcu
latio
n of
HN
O3
μm
ol/m
ol
6.45 m 48.12 m
Uncertainty budget for the HNO3 for mole fractions of (0.1-0.2) µmol/mol
2HNO2
HNO2
HNO 33305.0017.0020.0)( xxxu
Signal stability MALT-CLS HITRAN database
Quantity Typical value Standard uncertaintyRelative
uncertainty
P 8.3573 μg min−1 4.18×10−3 μg min−1 5×10-4
Vm 22.4038 L mol−1 0.34×10-3 L mol−1 1.52×10-5
qv 452 mL min−1 0.455 mL min−1 1.00×10-3
MNO2 46.0055 g mol−1 1.40×10−3 g mol−1 3.04×10-5
xHNO3 0.104 μmol mol−1 0.021 μmol mol−1 2.02×10-1
MHNO3 63.013 g mol−1 1.17×10−3 g mol−1 1.86×10-5
xN2O4 0 nmol mol−1 0.866 nmol mol−1 N.A.
Quantity Value Standard Uncertainty
xNO2 8.86 μmol mol-1 0.03 μmol mol−1
Uncertainty budget for NO2 standards
2
33
2
2NO
HNOHNO
NO
mNO M
xMMqVPx
v
Accurate FT-IR spectroscopy measurements of nitrogen dioxide (NO2) and nitric acid (HNO3) calibrated with synthetic spectra, Edgar Flores*, Joële Viallon, Philippe Moussay and Robert Ian Wielgosz (APPLIED SPECTROSCOPY 67 (10), 1171-1178, 2013)
22Bureau International des Poids et Mesures
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Value assignment of cylinders with BIPM NO2 facility (KCRV)Flores E., et al. Final report on international comparison CCQM-K74: Nitrogen dioxide, 10 µmol/mol, Metrologia, 2012, 49, Tech. Suppl., 08005
Results of international comparison for NO2 standards (CCQM-K74)
Transfer Gas Standard NO2 mixture developed by VSLAmount of substance fraction~10 μmol/mol
Passivated aluminum cylinders of 5 L.
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Conclusions and Acknowledgments
• Strong collaboration and support of GUM through visiting scientists highly valued
• Leads to innovation and improved international agreement of standards at low levels of uncertainty
• Important for monitoring and decision making on Air Quality and Greenhouse Gas Measurements
• Many thanks to GUM and Krzysztof Tworek, Grzegorz Ochmann and Agata Rakowska
Future Outlook• BIPM welcomes the support of GUM for its continued programme into
2016-2019, addressing:• Carbon dioxide and Methane Standards (CCQM-K120)• Formaldehyde Standards (CCQM-K90)• Nitrogen Monoxide Standards