A Novel Downwind Odor Sampling Strategy for Transient Events

D. Wright – Don Wright & Associates, LLC F. Kuhrt & A. Iwasinska – Microanalytics-MOCON

D. Eaton – Epsilon CompanyJ. Koziel – Ag and Biosystems Engineering, Iowa State University

Acknowledgement

This work has been partially funded by the US Department of Agriculture under SBIR Phase II Grant – CSREES Award number 2007-33610-18619 to Microanalytics.

However

Any opinions, findings, conclusions, or recommendations expressed in this presentation are those of the author and do

not necessarily reflect the view of the US Department of Agriculture

Cereal Packaging Film – ‘Barnyard’ Malodor

‘Bad’ Film p-cresol

‘Good’ Film p-cresol

Conclusions from Project Report into Swine CAFO Study - 1996

It appears that p-cresol may be a priority odor impact compound relative to the swine-barn application.

If this is proven correct, sampling these environments with plastic bags is ill-advised.

The priority impact shown for phenol is believed to be a cross-contamination artifact; unrelated to the targeted swine-barn source.

Published References Addressing the Issue of Odorant Loss in Tedlar Bags

Keener et. al.; 2002; Evaluation of thermal desorption for the measurement of artificial swine odorants in the vapor phase; NC State, Transactions of the ASAE.

Koziel et. al.; 2005; Evaluation of sample recovery of malodorous livestock gases from air sampling bags, SPME fibers, Tenax TAsorbent tubes and sampling canisters; Texas A&M, JAWMA.

Trabue et.al.; 2006; Bias of Tedlar bags in the measurement of agricultural odorants; USDA-ARS Iowa, J of Environmental Quality.

Whole-Air Sample Bag Materials Optimization

Comparative p-Cresol Loss;Tedlar™ Versus m-FEP

753075Tedlar™

323075m-FEP

14123m-FEP

343075m-FEP

% LossHold Time (min)Temperature °CFilm Type

Prototype Inverted Metalized Film Sampling Bag

Sorbent Tube

Inert gas

Inertized, Heat-tracedReconstitute Canister

Comparative Phenol Loss Percentages for Various Films and Foils

9768726275T=0 + 22 hr

7549434050T=0 + 2.75 hr

5938332922T=0 + 1.5 min

NickleFoil

InvertedInc / Ag

w/o BHA

InvertedInc / Ag w BHA

InvertedAluminum

M-FEPStorageTime

Sorbent Tube to Whole-Air Sample

Thermal Reconstitution

ort

CombiPAL Autosampler

Cycle ComposerController

Patent Pending

Inert gas

Servo Drive

Heat-tracedReconstitute Canister

Gas Blending ModuleDiluent Gas

InputDesorptionInterface

Sample Bag

MultiTraxController

Z-Head

Desorption Tube

Prototype Thermal Reconstitution System

Patent Pending

Sorbent Tube

Inert gas

Servo Drive

Inertized, Heat-tracedReconstitute Canister

Background Comparison: Tedlartm vs Metalized FEP

5.00 10.00 15.00 20.00 25.00 30.00

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Abundance

TIC: SBR018.D\data.msTIC: SBR017.D\data.ms (*)

18 HOUR Fill and Hold

Tedlartm

m-FEP

Phenol

DMAC

Phenol Response Precision Out of TedlarShort-term – Same Day

32.80.238.23

32.11.209.52

31.26.118.71

n%RSDSD(ppb)

Mean(ppb)

Series

Long-Term – 21 Day

%RSDMeanDay 21Day 14Day 7Day 17.18.68.29.58.78.2

Comparative Phenol Loss: Direct m-FEP Bag Versus Sorbent Tube; Freezer Stored & Reconstituted

X313434T=0+10 min

5448485150T=0+2.75 hr

22T=0+1.5 min

ReconstitutedDay 21

ReconstitutedDay 14

ReconstitutedDay 7

ReconstitutedDay 1

DirectDay 1

Time

75T=0+23 hr

Carthage Industrial Bottoms Area

Prototype, Low-Cost Field DDO Device

US Pat. #8,429,950 B2

Field DDO Device; Continuously Variable Dilution Ratio

US Pat. #8,429,950 B2

6 liter / min = 11:1 dilution ratio

16 liter / min = 8:1 dilution ratio

Prototype, Field DDO ‘Screening’ Device; Continuously Variable, Audible Alarmed

US Pat. #8,429,950 B2

Summary

Regardless of source, odor analysis is, first and foremost, chemical analysis; carrying the same constraints and limitations with respect to sample handling and storage.

While always carrying the ‘potential’ for extreme complexity, the odor response to real world odor sources is often remarkably simple; with both positive and negative impacts primarily driven by very small subsets of the total source emission. Sampling strategies should be biased toward those highest-impact odorants.

Regardless of surface treatment, extended storage of polar, high-impact semi-volatile odorants in the gas phase is ill-advised. An optimized whole-air odor sampling strategy is presented whereby odorants are field collected onto an adsorbent bed, shipped and stored under refrigeration in advance of gas phase reconstitution; just prior to analysis or composite sensory assessment.

Post-Phase ITransient Event Sampling

Strategy Development

Odor Cued ‘Beep-Ball’

Comparative Naphthalene Yields: m-FEP Gas Bag Grab Sample With Sorbent Tube Transfer

(MS SIM area count responses)

Indirect ‘Peak’ Series83,915 count Run #1

54,851 count Run #2

11X ‘Lull’69,383 count Average

Indirect Interim ‘Lull’

Run #1 6,216 count .07X ‘Peak’

Representative Odor Threshold Curves

Patent Pending

Sorbent Tube

Inert gas

Servo Drive

Inertized, Heat-tracedReconstitute Canister

Increasing Concentration

Incr

easi

ng o

d or

inte

n si ty

Odor Threshold

Recognition Threshold

Saturation Threshold

Annoyance Threshold

Higher Impact OdorantLower Impact Odorant

Odor Point-Source Prioritization

Utilizing Tracer Gas Injection

Integrated Multi Point-Source Transient Odor Event Generator System

Odorant / Tracer Pair Response Ratio Precision

5n8.56% RSD.082sd.96Mean

1.07Run #5.95Run #4.96Run #3.98Run #2.84Run #1

Naphth / CCl3 Response RatioRun Number

Transient Event Sampling with Tracer Gas Injection for Point-Source Prioritization (MS SIM area count responses)

DMBCCl3Naphthalene‘Mothball’ Event

2,487412,334486,227Mean480386,036584,887Run #3390650,217653,343 Run #2

6,592200,750220,450 Run #1

30,7822,88926,334Mean3,7712,98817,428Run #3

84,3735,58035,053Run #24,203<dl26,522Run #1DMBCCl3Naphthalene‘Bluebonnet’ Event