June 23, 2009Office of Research and DevelopmentNational Risk Management Research Laboratory, Air Pollution and Prevention Control Division, RTP, NC

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Richard C. Shores, Alan F. Vette, Sue Kimbrough, Donald A. Whitaker, Victoria Martinez, Kevin N. Black, Richard Baldauf, Daniel A. Vallero,,

Integration of Gas Chromatographs into the FHWA/Environmental Protection Agency Near Road MSAT Study in Las Vegas, NV

1

Background – Identification of Research Problem

• FHWA Protocol specified the use of EPA methods TO-1 5 and TO-14 sampling methods for the measurement of MSAT’s.

�� The cost of labor, analysis and shipping limit the The cost of labor, analysis and shipping limit the number of samples collected. The protocol specified number of samples collected. The protocol specified one sample day for every twelve days of operation; one sample day for every twelve days of operation; four sites with QC require 1200 plus samples.four sites with QC require 1200 plus samples.

•• Gas chromatography with Gas chromatography with PIDPID detector detector

�� After the cost of initial purchase, the GC must be After the cost of initial purchase, the GC must be reliable, provide self contained operation, and reliable, provide self contained operation, and continuous data in a usable format. This presentat ion continuous data in a usable format. This presentat ion is reporting on the field evaluation of a GCis reporting on the field evaluation of a GC

2

Field Monitoring Location

• Sierra Club sued FHWA�NEPA process,

no established criteria to include MSATs

�FHWA has developed a tiered approach

• Unobstructed view of 400 meters

3Flows, normalized lamp response, network capable and ASCII output files for both calibration and measurement data. Optimized

BTEX SYSTEM

Column Type Metallic, L=30m, id=0.28mm

Actuator Valve 6 port, pneumatic

Detector type Photo Ionization Detector (PID), 10.6eV Lamp

Carrier gas Nitrogen

Trap type Carbotrap

Thermo-Desorption Temperature 380oC

Cycle time 15 to 30 minutes

Detection Range 0.3 to 320 µg/m3

Detection Limit 10 ppt

Relative standard deviation on concentration <3%

Relative standard deviation on retention time <0.3%

Calibration Benzene Permeation Tube, Fully automatic, self adjustable

Field GC Description

4

GC Evaluation Procedure• Comparison to the TO-15 criteria�Method detection limit of ≤≤≤≤ 0.5 ppb, replicate

precision within 25 percent, accuracy within 30 percent

• Comparison to the canister results�Method detection limit of ≤≤≤≤ 0.5 ppb, replicate

precision within 25 percent, accuracy within 30 percent

• Operate one GC in the field while canister samples are collected�Decide if the purchase of three additional GCs is

justified

5

31.19/1.6132.01/2.47820

13.68/0.5313.03/0.74810

6.0/0.474.87/0.3945

1.93/0.091.42/0.12132

0.81/0.180.53/0.1271

BenzeneAvg/Std

ButadieneAvg/Std

n, pointsConc., ppb, 1/23/09Benzene QC

15

16

17

18

19

20

21

22

23

24

25

1/17/09 1/27/09 2/6/09 2/16/09 2/26/09 3/8/09 3/18/09

Date

Ben

zene

, pp

b

Calibration and QC Control

6

GC Comparison to TO-15 Method

�Method detection limit for 1,3-butadiene and benzene ranged from 0.28 to 0.57 ppb, calculated for 1 and 2 ppb. Method specifies 0.5 ppb.�Average method detection limit of 0.4 ppb.�Precision results are within 6 percent, calculated for 20 ppb. Method specifies 25 percent.�Accuracy better than 30 percent. Method specifies 30 percent.

7

0

200

400

600

800

1000

1200

1400

1600

1800

2000

01/1

5/09

01/2

7/09

02/0

8/09

02/2

0/09

03/0

4/09

03/1

6/09

03/2

8/09

04/0

9/09

04/2

1/09

05/0

3/09

05/1

5/09

Date

But

adie

ne, B

enze

ne,S

tyre

ne C

onc,

ppt

0.00

2.00

4.00

6.00

8.00

10.00

12.00

Tol

uene

, m- ,

p- ,

o-xy

lene

Con

c, p

pb

1,3-butadiene

Benzene

Toluene

m-, p-xylene

Styrene

GC Measurement Data

8

Field GC and Canister Data Comparison

0

250

500

750

1000

Jan-09 Feb-09 Mar-09 Mar-09

Ben

zene

, ppt

Field GC

Canister

Benzene, No Zero Data

y = 1.2885x - 100R2 = 0.85

0.0

250.0

500.0

750.0

0.0 250.0 500.0 750.0

Gas Chromatograph, ppt

Can

iste

r S

ampl

ing,

pptGC Comparison to

Canister Results -Benzene

9

Field GC and Canister Data Comparison

10

260

510

760

Jan-09 Jan-09 Feb-09 Feb-09 Mar-09 Mar-09 Apr-09

But

adie

ne, p

pt

Field GC

Canister

GC Comparison to Canister results -Butadiene

Butadiene, No Zero Data

y = 1.3211x - 50R2 = 0.51

0.0

50.0

100.0

150.0

200.0

250.0

0.0 50.0 100.0 150.0 200.0 250.0 300.0 350.0

Gas Chromatoghry Data, ppt

Can

iste

r Dat

a, p

pt

10

Benzene - Hourly Averages

-50

0

50

100

150

200

250

300

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour

Con

cent

ratio

ns -

ppt

Auto GC

Canister

11

Canister Results Evaluation�Majority of the 1,3-butadiene and benzene concentrations have been less than 2 ppb

�Accuracy on average 30% for both butadiene and benzene

�Significantly more data, 43 canister samples versus 1200 benzene concentrations from the GC

�Canister method detection limit ~40 ppt and GC method detection limit ~ 100 ppt

�The GC has been operating for the past six months, unattended, data is down loaded remotely

�Three more GC’s are being purchased to install in the remaining three sites

12

• Acceptable comparison to the TO-15 method.• Acceptable comparison to the canister results.• Significant operational savings.• Continuous data – 30 min cycles.• Purchase and install GCs in the additional shelters.

• Continue canister sampling for QA/QC verification but reduce the number of samples taken.

GC Evaluation Summary

13

Acknowledgements

We thank Brian Schumacher and Jeffery Lantz of the EPA Las Vegas Facility for their continuing support of this project. We thank Michal Derlickiand the other ARCADIS staff along with the staff of Alion Science and Technology .