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)