Preparation of nitrous oxide in air standard (320 nmol/mol) for CCQM-K68 8th APMP/TCQM Gas CRM Workshop June 10 th, 2010 Tukuba, Ibaraki, Japan Nobuyuki Aoki, Takuya Shimosaka, Nobuhiro Matsumoto, Kenji Kato (National Metrology Institute of Japan, AIST)
Table of contents Background of CCQM-K68 Outline of CCQM-K68 Preparation procedure Purity analysis of parent gas Weighing process of filling gas Result of CCQM-K68 Summary
Background 300 times GWP of CO 2 0.2-0.3 %/yr(0.8ppb/yr) It is necessary to harmonize calibration scale
Outline of CCQM-K68 Pilot laboratory Component KRISS Nitrous Oxide in synthetic air Concentration Target uncertainty 0.1 % Supported claims Participants objective 320 nmol/mol N 2 O in synthetic air at atmospheric level with the uncertainty within calibration scale of global monitoring division NMIJ, VSL, NIST, VNIM, NIM, KRISS, NOAA* 1, IMK-IFU* 2 Comparison of the measurement capability of N 2 O at a trace level of 320 nmol/mol * 1 NOAA is the Central Calibration Laboratory to maintain WMO scale * 2 IMK-IFU is a World Calibration Centre for N 2 O to take over Quality Assurance and Quality Control (QA/QC) to combine N 2 O measurements from different sites and different monitoring programs responsibility.
Preparation procedure Gravimetric value x i = P i, A A n n A= 1 A= 1 x j, A M j x j= 1 m P j= 1 x m A j, A M j x j,a : mol fraction of the component Purity of parent gas SI Amount of substance (mol) Impurity analysis with primary standards m A : mass of parent gas Amount of parent gas Mass (kg) Weighing with balance calibrated by the mass piece M j : Molar mass IUPAC Atomic weight Relative mass
Purity analysis of raw materials Purity table of N 2 Purity table of N 2 O Components Applied concentration (μmol/mol) Standard uncertainty (μmol/mol) Analytical method N 2 0.983 0.567 Micro GC O 2 1.020 0.589 Micro GC CO 2 0.128 0.006 GC-FID with methanizer CH 4 0.019 0.003 GC-FID CO 0.056 0.032 H 2 O 0.439 0.253 N 2 O 999997.36 GC-FID with methanizer Capacitance-type moisture meter Components Components Applied concentration (μmol/mol) Applied concentration (μmol/mol) Standard uncertainty (μmol/mol) Analytical method N 2 0.090 0.052 GC-TCD Ar 0.087 0.050 GC-TCD CO 2 0.056 0.004 FT-IR CH 4 0.003 0.002 FT-IR CO 0.005 0.003 FT-IR H 2 O 0.439 0.253 Capacitance-type moisture meter N 2 O 0.00002 0.00001 Clyo. conc. /GC/MS O 2 999999.32 Standard uncertainty (μmol/mol) Analytical method O 2 0.819 0.473 Micro GC CO 2 0.010 0.006 FT-IR CH 4 0.026 0.015 FT-IR CO 0.175 0.101 FT-IR H 2 O 0.439 0.253 Capacitance-type moisture meter N 2 O 0.00002 0.00001 Clyo. conc. /GC/MS N 2 999998.53 Purity table of O 2
Analytical system for impurity N 2 O in N 2, O 2 pump Module 1 Module 2 Module 1 Module 2 Module 3 Tenax Glass bead Module 3 Precolum forcouser -120 C -150 C -180 C 20 C 150 C 70 C GC-MS Column: Pora PLOT Q 0.32mm 25m Oven: 50 Time: 12min Carrier gas: He 2.0ml/min Mode: SIM(mass:30)
N 2 O concentration in O 2 and N 2 140000 120000 N 2 O was not detected! 100000 Area 80000 60000 40000 The value was determined from detection limit 20000 0 0.00 0.50 1.00 1.50 2.00 Concentration (nmol/mol)) N 2 O in He (gravimetric method) He (nmol/mol) 0.149 1.141 1.521 Concentration(x d ) = Detection limit 2 Standard uncertainty(u xd ) Detection limit = 3 N 2 O value in dilution gases are 0.02±0.02 nmol/mol The uncertainty is expanded uncertainty with the coverage factor of 2
Weighing process Main source of uncertainty Balance Buoyancy effect Absorption and adsorption to external cylinder surface.etc Comparative Weighing Weighing room 25 C, 50% Filling room 24 C, 20~80% Mixture Reference 12.123456 kg Alternately-measured an hour after filling parent gas five hours after filling dilution gases N 2 O or N 2 O in N 2 N 2 or O 2
Weighing system of NMIJ Mixture cylinder Reference cylinder Electric mass comparator Max=15kg, d=1mg Automatic cylinder exchanger Standard uncertainty of balance system : 2.6 mg!
Preparation protocol N 2 O, N 2 CPB16182 CPB16250 CPC00878 CPB16181 CPB16252 1 step 1.3-1.5 %mol/mol Expanded uncertainty: 0.04 % N 2 CPB16174 CPB16178 CPC00871 CPB16176 CPB28390 2 step 280-300μmol/mol Expanded uncertainty: 0.05 % N 2 CPB16185 CPB16184 CPB16187 CPB16186 CPB16183 3 step 9.0-10μmol/mol Expanded uncertainty: 0.06 % N 2, O 2 CPB16463 CPB31362 CPC00877 CPC00415 CPB16468 4 step 300-345nmol/mol Expanded uncertainty: 0.06 % Five standards were independently prepared!
Verification of parent gases 1 step Deviation between five values < ± 0.15 % Internal consistency test check that gravimetric value is consistent with analytical value highlight significant errors in the preparation process FT-IR 3 step 2 step Deviation between five values < ± 0.08 % FT-IR Deviation between five values < ± 0.06 % GC-ECD
N 2 O standards of NMIJ Cylinder number Gravimetric Value (nmol/mol) Expanded uncertainty (nmol/mol) [k=2] Calculated Value (nmol/mol) Deviation (nmol/mol) CPB00877 303.57 0.13 303.54 0.03 CPB31362 312.77 0.19 312.84-0.07 CPB16468 326.44 0.20 326.37 0.07 CPC00415 338.20 0.20 338.10 0.10 CPB16463 343.73 0.23 343.84-0.11
Analytical system
Chromatogram Column: Porapak-Q(80/100), 1.2m(1/8inch) Oven: 30 C ECD: 345 C Carrier gas: N 2 (10ml/min) Make up gas: ArCH 4 (10ml/min) A good chromatogram was obtained!
Draft A report of CCQM-K68 Draft of CCQM-K68 Relative deviation (%) NMIJ Laboratory Y axis =(Analysis value)-(kcrv) Reported value of NMIJ is in excellent agreement with key comparison reference value (KCRV)
Summary N 2 O concentration in N 2 and O 2 is estimated by preconcentration GC-MS N 2 O standards traceable to SI have been prepared Analysis result of is in excellent agreement with KCRV in CCQM-K68
This study NMIJ Preparation of N 2 O standard traceable to SI Evaluation of NIES standards NIES Measurement of NMIJ standards by GC-ECD of NIES Evaluation of NMIJ standards NMIJ (Japan) NMis International comparison (CCQM-K68) Pilot laboratory KRISS ( KRISS ) WMO IMK-IFU NOAA NMi-VSL (Netherlands) NIST (USA) NMi (China) VNIIM (Rossia)