Preparation of nitrous oxide (N 2 O) in air standard being traceable to SI by gravimetric method

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Francine Stevens
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1 Preparation of nitrous oxide ( O) in air standard being traceable to SI by gravimetric method 15th WMO Meeting of Experts on Carbon Dioxide, Other Greenhouse Gases, and Related Tracer Measurement Techniques September 7 th, 2009 Jena, Germany Nobuyuki Aoki, Takuya Shimosaka, Nobuhiro Matsumoto, Kenji Kato (National Metrology Institute of Japan, AIST) Keiichi Katsumata, Toshinobu Machida (National Institute for Environmental Studies)

2 O standard O WMO Round-Robin intercomparison ( ) 1 step International comparison among National Metrology Institutes (NMI) CIPM International Committee of Weights and Measures 2 step Air CCQM the Consultative Committee for Amount of Substance 250 nmol/mol 300 nmol/mol 3 step nmol/mol 350 nmol/mol 400 nmol/mol preparation sequence of NIES-standard courtesy of Dr. Zhou Lingxi CCQM-K68 Analysis of O standard prepared in pilot laboratory (KRISS) Component: O in air Concentration: 320nmol/mol Time of measurement: Status: in progress

This study NMIJ Preparation of O standard traceable to SI Evaluation of NIES standards Linkage to NMIJ NIES Measurement of NMIJ standards using NIES-standards comparison of NMIJ and NMI

3 This study NMIJ Preparation of O standard traceable to SI Evaluation of NIES standards Linkage to NMIJ NIES Measurement of NMIJ standards using NIES-standards comparison of NMIJ and NMI standards Traceable to NMI NMIs International comparison (CCQM-K68) WMO NMIJ (Japan) Pilot laboratory ( KRISS, Korea ) IMK-IFU NOAA NMi-VSL (Netherlands) NIST (USA) NIM (China) VNIIM (Rossia)

4 Gravimetric method traceable to SI 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 SI x j,a : mol fraction of the component in parent gas O O 2 purity analysis Measurement of Impurity with primary standards Amount of substance (mol) m A : mass of parent gas kg Weighing amount of gases by standard mass piece Mass (kg) Weighing Verification M j : Molar mass of component IUPAC Atomic weight Relative mass

5 Purity analysis of raw materials Purity table of Purity table of O Components Applied concentration (μmol/mol) Standard uncertainty (μmol/mol) Analytical method Micro GC O Micro GC CO GC-FID with methanizer CH GC-FID CO H 2 O O GC-FID with methanizer Capacitance-type moisture meter Purities of all raw materials are more than % Components Components Applied concentration (μmol/mol) Applied concentration (μmol/mol) Standard uncertainty (μmol/mol) Analytical method GC-TCD Ar GC-TCD CO FT-IR CH FT-IR CO FT-IR H 2 O Capacitance-type moisture meter O Clyo. conc. /GC/MS O Standard uncertainty (μmol/mol) Analytical method O Micro GC CO FT-IR CH FT-IR CO FT-IR H 2 O Capacitance-type moisture meter O Clyo. conc. /GC/MS Purity table of O 2

6 O concentrations in O 2 and Analytical system for impurity O Calibration standards O in He (gravimetric method) 0.149, 1.141, nmol/mol GC-MS Module 1 Module 2 Module 3 adsorbent Tenax Glass beads Capillary colmn Trap Temp PoraPLOT Q 0.32 mm ID 25 m Desorb Temp Area Calibration curve DL=0.04 nmol/mol Concentration (nmol/mol)) O concentrations in O 2 and are less than 0.04 nmol/mol

7 Weighing Main sources of uncertainty Balance Buoyancy effect Absorption and adsorption to external cylinder surface. etc. Comparative Weighing Weighing room Filling room Mixture Reference 25 C, 50% 24 C, 20~80% kg Alternately-measured an hour after filling parent gases five hours after filling dilution gases O or O in or O 2

8 Weighing system of NMIJ Mixture cylinder Reference cylinder Electric mass comparator Max=15kg, d=1mg Automatic cylinder exchanger Standard deviation of balance system : 2.6 mg!

9 Preparation sequence O, CPB16182 CPB16250 CPC00878 CPB16181 CPB st step %mol/mol Expanded uncertainty: 0.04 % CPB16174 CPB16178 CPC00871 CPB16176 CPB nd step μmol/mol Expanded uncertainty: 0.05 % CPB16185 CPB16184 CPB16187 CPB16186 CPB rd step μmol/mol Expanded uncertainty: 0.06 %, O 2 CPB16463 CPB31362 CPC00877 CPC00415 CPB th step nmol/mol Expanded uncertainty: 0.06 % Five standards of 4th step were independently prepared!

10 Verification of intermediated gases 1 step Deviation between both 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 both values < ± 0.08 % FT-IR Deviation between both values < ± 0.06 % GC-ECD

11 O standards of NMIJ Column: Porapak-Q(80/100) 1.2m(1/8inch) Oven: 30 C ECD: 345 C Carrier gas: (10ml/min) Make up gas:arch 4 (10ml/min) Cylinder number Gravimetric Value (nmol/mol) Expanded uncertainty [k=2] (nmol/mol) Concentration with calibration carve (nmol/mol) Deviation (nmol/mol) CPB CPB31362 CPB16468 CPC00415 CPB

12 Comparison between NMIJ and NIES standards ±0.1% NIES scale is comparable to SI

13 Draft report of CCQM-K68 Relative deviation (%) NMIJ Key comparison reference value (KCRV) Laboratory Y axis = (Analysis value)-(kcrv) Analysis result of NMIJ is in excellent agreement with key comparison reference value (KCRV)

14 Summary O standards traceable to SI have been prepared at NMIJ The scale of NIES-standards is linkage to the scale of NMIJ-standards Analysis result of NMIJ is in excellent agreement with KCRV in CCQM-K68 The scale of NIES-standards will be comparable to NMI

16 International comparison among NMi Measurement capability CCQM-K68 : Nitrous oxide 320 nmol/mol in artificial Air Gravimetric preparation of N2O by coordinating lab. Purity Assessment + Weighing Technique + Stability + Verification N2O 300 ~ 350 nmol/mol ± 0.06 % (95 % confidence level) How far does the light shine This key comparison will support the measurement capability of O at ambient level Participation(8) KRISS, NIM, NIST, NMIJ, GMD/NOAA, VSL, IMK-IFU, VNIIM

17 Uncertainty Main source of uncertainty Purity of raw material Balance mass piece adsorption/desorption buoyancy effect molar mass

Preparation of nitrous oxide in air standard (320 nmol/mol) for CCQM-K68

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