jerry rhoderick and christina liaskos
TRANSCRIPT
Jerry Rhoderick and Christina Liaskos
Gas Sensing Metrology GroupChemical Sciences Division
National Institute of Standards and Technology100 Bureau Drive, MS‐8393
Gaithersburg, Maryland 20899‐8393 USA
5th WMO/GAW‐VOC Expert Workshop on Volatile Organic CompoundsKRISS, Daejeon, Republic of Korea
October 20‐24, 2014
Recap of 4th WMO/GAW‐VOC meeting in York, UK, 2012
• Air Products aluminum w/ Experis treatment very promising• Nickel plate steel cylinders show degradation, but at a much slower
rate than Aculifed aluminum
• Results indicated stable mixtures of α‐pinene, β‐pinene, 3‐carene, p‐cymene, R‐limonene, and camphene (300+ days)
• 1,8‐cineole at 70+ days
• Based on discussions and request at York meeting, NIST submitted proposal to become WMO CCL for monoterpenes in Dec 2012
• NIST became official WMO CCL for Monoterpenes in Feb 2013
Continued Stability Study of Monoterpene Standard D646508
• Error bars are expanded uncertainties (U) based on standard deviations (sd) of the average response of replicate measurements (n) of the individual terpene and benzene, where n = 3 to 5; U = [sqrt (sd 2
terpene + sd 2benzene) *2] *Ratio
“Stability Assessment of Gas Mixtures Containing Monoterpenes in Varying Cylinder Materials and Treatments”, G.C.Rhoderick, Janice Lin, Analytical Chemistry, Vol.85 (9) pp. 4675‐4685, 2013.
Monoterpene Standards Preparation Timeline
APE1082180225 ppbα-pinene3-carenelimonene1,8-cineolen-hexane (IS)prepared 21/8/2013
APE11359132 ppb prepared 25/09/2013
APE11359152 ppb prepared 30/01/2014
APE1135902225 ppbα-pinene3-carenelimonene1,8-cineolen-octane (IS)prepared 16/04/2014
Aug 2013 | Oct 2013 | Dec 2013 | Feb 2014 | Apr 2014 | Jun 2014 | Aug 2014 | Oct 2014
stability check
APE1135917225 ppbß-pinenecampheneα-terpinenep-cymenen-octane (IS)prepared 23/07/2014
APE1135894225 ppbß-pinenecampheneα-terpinenep-cymenen-octane (IS)prepared 15/09/2014
stability/cross check
consistency check
Impurities/Purity of Starting Monoterpenes
Error bars are combined uncertainties, k=1.
Tracking Stability in APE1082180; 250 nmol mol‐1
1.50
1.52
1.54
1.56
1.58
1.60
1.62
1.64
1.66
1.68
1.70
0 50 100 150 200 250 300 350 400
Ratio
to n‐Hexane
Days from Preparation
α‐Pinene and 3‐Carene in APE1082180
α‐Pinene
3‐Carene
• Ratios (monoterpene/n‐hexane peak areas) over time from preparation date• Error bars are standard deviations (sd) of replicate measurements (n) of the individual
terpene and n‐hexane, where n = 3 to 5; u = [sqrt (sd 2terpene + sd 2
n‐hexane) ] *Ratio
1.50
1.52
1.54
1.56
1.58
1.60
1.62
1.64
1.66
0 50 100 150 200 250 300 350 400
Ratio
to n‐Hexane
Days from Preparation
Limonene and 1,8‐Cineole in APE1082180
Limonene
1,8‐Cineole
Tracking Stability in APE1082180; 250 nmol mol‐1
Stability Determined vs. New StandardGrave Va
lue, August 2
1,20
13
vs. APE11
3590
2, April 30
,201
4
vs. APE11
3590
2, April 21
,201
4
vs. APE11
3590
2, August ,20
14
180.00
190.00
200.00
210.00
220.00
230.00
240.00
250.00
Concen
tratio
n, nmol/m
ol
APE1082180 analyzed vs. new standard APE1135902
Grav Value :Aug 21,2013
vs.APE1135902,April 21,2014
vs.APE1135902,April 30,2014
vs.APE1135902,Aug 22,2014
α‐pinene 3‐carene R‐limonene 1,8‐cineole
• Original standard APE1082180 prepared August 21, 2013• New standard APE1135902 prepared April 16, 2014• Error bars are expanded uncertainties, 95 % confidence interval
Tracking Stability in APE1135913; 2 nmol mol‐1
• Ratio of monoterpene to n‐hexane over time from preparation date
1.52
1.54
1.56
1.58
1.6
1.62
1.64
1.66
1.68
0 50 100 150 200 250 300
Ratio
to n‐He
xane
Days from Preparation
a‐pinene
3‐carene
à‐pinenestart line
3‐carenestart line
1.46
1.51
1.56
1.61
1.66
1.71
0 50 100 150 200 250 300
Ratio
to n‐He
xane
Days from Preparation
limonene
1,8‐cineole
1,8‐cineolestart line
limonenestart line
Tracking Stability in APE1135913; 2 nmol mol‐1
• Ratio of monoterpene to n‐hexane over time from preparation date
• Error bars are expanded uncertainties, 95 % confidence interval
NIST Determinations of NPL Standard D910392
Tracking Stability in APE1135917; 225 nmol mol‐1
0.64
0.69
0 10 20 30 40 50 60 70 80 90 100Ratio to n‐O
ctan
e
Days from Preparation
α‐Terpinene
Linear (α‐Terpinene start line)
1.05
1.15
1.25
1.35
1.45
0 10 20 30 40 50 60 70 80 90 100
Ratio to n‐O
ctan
e
Days from Prepartion
Camphene
ß‐Pinene
p‐Cymene
Linear (Camphenestart line)
Linear (ß‐Pinene startline)
Linear (p‐Cymene startline)
Future Work/Collaborations with other NMIs
• Continue comparisons of monoterpenes with other National Metrology Institutes
• Continue stability studies
• Further development of “2nd Group” of monoterpene standards at 2 ppb• β-pinene, camphene, α-terpinene, p-cymene
• Planned CCQM/GAWG key comparison (K-121) on monoterpenes at 2 ppb level• NIST coordinating; participants include NPL, NIM, KRISS• Underway with participant analyses of samples planned for 2015• α-pinene, 3-carene, limonene, 1,8-cineole
NIST PSM and Reference Materials Development to Support Measurements of Atmospheric and Air Pollution Species PSMs developed for:
- greenhouse gases CO2, CH4, N2O, CO, SF6- halocarbons including CFC-12, CFC-11, CFC-113, HCFC-22, HCFC-142b, HFC-134a, CFC-114, HCFC-141b, HFC-152a, HFC-143a
- VOCs: 80+ light & heavey hydrocarbons, aromatics, chloro/fluoro species- monoterpenes : α‐pinene, 3-carene, limonene, 1,8-cineole, β -pinene, camphene, terpinene, p-cymene (others being studied)
- oxygenates methanol, ethanol, acetone- developing methods for ammonia, HCHO, HCl
SRMs completed or near completion:- 1718 N2O in Synthetic Air at 1000 ppb- 1720 Northern Continental Air (Dry) and 1721 Southern OceanicAir with CO2, CH4, N2O certified; informational values for O2,Ar, CO, 13C-CO2 and 18O
- SRM 1722 Halocarbons in Air (Northern Continental)