FEASIBILITY OF A NEW DIFFUSIVE FEASIBILITY OF A NEW DIFFUSIVE SAMPLER TO MEASURE SUB-PPB SAMPLER TO MEASURE SUB-PPB

LEVELS OF VOCsLEVELS OF VOCs

Linda Coyne Linda Coyne Cindy KuhlmanCindy Kuhlman

SKC Inc.SKC Inc.Eighty Four, PAEighty Four, PA

BackgroundBackground

Canisters are routinely used to sample Canisters are routinely used to sample VOCs at sub-ppb levels.VOCs at sub-ppb levels.

Canisters provide accurate, sensitive, and Canisters provide accurate, sensitive, and reproducible measurements.reproducible measurements.

However, they have a number of logistical However, they have a number of logistical disadvantages including size, expense, disadvantages including size, expense, and training required for use.and training required for use.

Diffusive Samplers: A Possible Diffusive Samplers: A Possible Alternative to CanistersAlternative to Canisters

ADVANTAGESADVANTAGES Inexpensive and Inexpensive and

simple to operatesimple to operate Lightweight and Lightweight and

unobtrusiveunobtrusive

DISADVANTAGESDISADVANTAGES Sensitivity issuesSensitivity issues Reverse diffusion Reverse diffusion

effectseffects Demonstrate Demonstrate

“starvation” at face “starvation” at face velocities less than velocities less than 5 cm/sec5 cm/sec

Diffusive Samplers: Widely Diffusive Samplers: Widely studied for ppm levelsstudied for ppm levels

Many studies have Many studies have been published on been published on the use of badge the use of badge style diffusive style diffusive samplers for samplers for industrial hygiene industrial hygiene applications using applications using solvent extraction solvent extraction and analysis by and analysis by GC/FID/MSGC/FID/MS

Data indicates Data indicates badges produce badges produce consistent and consistent and accurate accurate measurements for measurements for many compounds.many compounds.

Validation studies Validation studies have documented have documented reliable results reliable results under various under various conditions of use. conditions of use.

Diffusive Samplers: New studies Diffusive Samplers: New studies for sub-ppm levelsfor sub-ppm levels

New StudiesNew Studies

– Marines: Nerve agentsMarines: Nerve agents– OSHA: VOCs for Indoor AirOSHA: VOCs for Indoor Air– Sweden: 1,3-butadiene and benzeneSweden: 1,3-butadiene and benzene

Diffusive Samplers: Indoor and Diffusive Samplers: Indoor and Ambient Air StudiesAmbient Air Studies

In order to In order to consistently consistently measure sub-ppb measure sub-ppb and ppt levels of and ppt levels of VOCs with a VOCs with a diffusive sampler, diffusive sampler, thermal desorption thermal desorption must be used.must be used.

Ultra BadgeUltra Badge

A modification of the SKC 575-series solvent-A modification of the SKC 575-series solvent-desorption badge for VOCs was made which desorption badge for VOCs was made which added an aluminum funnel to back of badge.added an aluminum funnel to back of badge.

The funnel allowed for transfer of sorbent from The funnel allowed for transfer of sorbent from badge to tube.badge to tube.

The tube could then be analyzed by thermal The tube could then be analyzed by thermal desorption.desorption.

Sorbent Storage and Transfer Sorbent Storage and Transfer from Badgefrom Badge

Initial Problems Discovered Initial Problems Discovered

– Sorbent could not be stored for any length of Sorbent could not be stored for any length of time in badge housing due to contamination.time in badge housing due to contamination.

– The use of SS tubes did not allow users to see The use of SS tubes did not allow users to see the sorbent transfer.the sorbent transfer.

– Field tests indicated that users did not like to Field tests indicated that users did not like to handle tube separators that were used to seal handle tube separators that were used to seal the tube after transfers.the tube after transfers.

NEXT DEVELOPMENT: NEXT DEVELOPMENT:

ULTRA II SAMPLERULTRA II SAMPLER

ULTRA II DESIGN ULTRA II DESIGN MODIFICATIONSMODIFICATIONS

Built-in funnel was redesigned such Built-in funnel was redesigned such that a 4-mL screw cap vial could be that a 4-mL screw cap vial could be attached to back of badge.attached to back of badge.

User can easily see the transfer of User can easily see the transfer of sorbent.sorbent.

Front and Back of SamplerFront and Back of Sampler

Filling the SamplerFilling the Sampler

Emptying the SamplerEmptying the Sampler

Ultra II Diffusive SamplerUltra II Diffusive Sampler

BEFORE SAMPLINGBEFORE SAMPLING Sorbent contained in a Sorbent contained in a

vial can be transferred vial can be transferred to the badge to the badge immediately before immediately before sampling, which sampling, which addresses addresses contamination contamination concerns. concerns.

AFTER SAMPLINGAFTER SAMPLING The sorbent can be The sorbent can be

transferred back to transferred back to vial and capped for vial and capped for shipment to the lab. shipment to the lab.

In the laboratory, the In the laboratory, the sorbent can be sorbent can be transferred to a TD transferred to a TD tube for analysis.tube for analysis.

Sampling Accessories: Vial Sampling Accessories: Vial Containing the SorbentContaining the Sorbent

Sampling Accessories: Sampling Accessories: Sampling StandSampling Stand

Evaluation of the Ultra II Evaluation of the Ultra II SamplerSampler

Duplicate precisionDuplicate precision Audit accuraciesAudit accuracies Method reporting limitsMethod reporting limits Storage studies of both tubes and Storage studies of both tubes and

vialsvials Sampling rates of badge for target Sampling rates of badge for target

compoundscompounds

VOCs EvaluatedVOCs Evaluated VAPOR INTRUSIONVAPOR INTRUSION

APPLICATIONSAPPLICATIONS

Trichloroethylene Trichloroethylene and and perchloroethylene perchloroethylene were evaluated as were evaluated as typical compounds.typical compounds.

OTHER OTHER APPLICATIONSAPPLICATIONS

Benzene, toluene, Benzene, toluene, xylenes, heptane, xylenes, heptane, and 1,2-DCE were and 1,2-DCE were also evaluated. also evaluated.

Sample Media SelectionSample Media Selection

REFERENCE METHODREFERENCE METHOD EPA Compendium EPA Compendium

Method TO-17 was Method TO-17 was used as a reference used as a reference to select the best to select the best sorbent media for sorbent media for these compoundsthese compounds

SORBENTS USEDSORBENTS USED Tenax TA Tenax TA

(20/35 mesh)(20/35 mesh)

Anasorb GCB1 Anasorb GCB1 (60/80 mesh)(60/80 mesh)– Equivalent to Equivalent to

Carbopack BCarbopack B

Analytical ConditionsAnalytical Conditions Samples were desorbed using a Perkin Samples were desorbed using a Perkin

Elmer Turbomatrix ATD.Elmer Turbomatrix ATD.

Focusing trap was a dual bed of Tenax TA Focusing trap was a dual bed of Tenax TA and Carbopack B.and Carbopack B.

Separation was performed using a Perkin Separation was performed using a Perkin Elmer Clarus 500 FID/GC.Elmer Clarus 500 FID/GC.

Performance CriteriaPerformance Criteria

Method reporting Method reporting limitslimits

Audit accuraciesAudit accuracies

PrecisionPrecision

Sampling Rates and MRL for Sampling Rates and MRL for VOCsVOCs

Compound SR Compound SR MRL MRL 8-h 8-h 24-h 24-h (mL/min) (ng) (ppt) (mL/min) (ng) (ppt) (ppt) (ppt)

Ethylbenzene Ethylbenzene 12.912.9 0.95 0.95 35.335.3 11.8 11.8

BenzeneBenzene 16.016.0 0.87 0.87 35.435.4 11.8 11.8

p-Xylenep-Xylene 12.812.8 0.95 0.95 35.635.6 11.9 11.9

o-Xyleneo-Xylene 11.911.9 0.95 0.95 38.338.3 12.8 12.8

Dichloroethane Dichloroethane 14.214.2 1.1 29.9 1.1 29.9 13.3 13.3

Sampling Rates and MRL for Sampling Rates and MRL for VOCsVOCs

Compound SR Compound SR MRL MRL 8-h 8-h 24-h 24-h (mL/min) (ng) (ppt) (ppt) (mL/min) (ng) (ppt) (ppt)

HeptaneHeptane 13.9 13.9 1.1 1.1 40.240.2 13.4 13.4

Toluene 14.5Toluene 14.5 0.87 0.87 33.233.2 11.1 11.1

Chlorobenzene 14.2 0.87Chlorobenzene 14.2 0.87 27.727.7 9.2 9.2

Trichloroethylene 12.9 1.1Trichloroethylene 12.9 1.1 33.133.1 11.0 11.0

Perchloroethylene 14.9Perchloroethylene 14.9 2.2 2.2 48.4 48.4 15.1 15.1

Storage of TCE and PCE Storage of TCE and PCE on Tenax TA in Tubes, - 3 C on Tenax TA in Tubes, - 3 C

(%Recovery ±RSD)(%Recovery ±RSD)

Storage Time Storage Time (weeks(weeks))

Trichloroethylene Trichloroethylene (10 ng)(10 ng)

PerchloroethylenePerchloroethylene

(10 ng)(10 ng)

1 week 1 week 106 ±8.0106 ±8.0 67.0 ±1167.0 ±11

2 weeks2 weeks 112 ±19112 ±19 103 ±9.3103 ±9.3

3 weeks3 weeks 121 ±14121 ±14 117 ±8.3117 ±8.3

Storage of TCE and PCE Storage of TCE and PCE on Anasorb GCB1 in Tubes, - 3 Con Anasorb GCB1 in Tubes, - 3 C

(%Recovery ±RSD)(%Recovery ±RSD)

Storage time Storage time TrichloroethyleneTrichloroethylene PerchloroethylenePerchloroethylene

1 week1 week 96.2 ±5.396.2 ±5.3 101 ±4.7101 ±4.7

Storage of TCE and PCE Storage of TCE and PCE Tenax TA in Vials, - 3 CTenax TA in Vials, - 3 C

(%Recovery ±RSD)(%Recovery ±RSD)

Storage time (weeks)Storage time (weeks) Trichloroethylene Trichloroethylene

(10 ng)(10 ng)PerchloroethylenePerchloroethylene

(10 ng)(10 ng)

1 week1 week 122 ±1.0122 ±1.0 82.5 ±6.182.5 ±6.1

2 weeks2 weeks 150 ±17150 ±17 54.9 ±2554.9 ±25

3 weeks3 weeks 89.5 ±16.789.5 ±16.7 90.6 ±3.190.6 ±3.1

Storage of TCE and PCEStorage of TCE and PCE on Anasorb GCB1 in Vials, - 3 C on Anasorb GCB1 in Vials, - 3 C

(%Recovery ±RSD)(%Recovery ±RSD)

Storage timeStorage time TrichloroethyleneTrichloroethylene PerchloroethylenePerchloroethylene

1 week1 week 122 ±16122 ±16 126 ±18126 ±18

2 weeks2 weeks 115 ±3.9115 ±3.9 82.95 ±2.182.95 ±2.1

3 weeks3 weeks 94.8 ±8.294.8 ±8.2 96.6 ±8.096.6 ±8.0

Audit Accuracies on Tenax TA Audit Accuracies on Tenax TA TrichloroethyleneTrichloroethylene

CompoundCompound Level (ng)Level (ng) Accuracy (%)Accuracy (%)TrichloroethyleneTrichloroethylene 2.22.2 127127

5.55.5 120.7120.7

10.9810.98 107.7107.7

24.224.2 88.2 88.2

54.954.9 87.5 87.5

109.8109.8 87.1 87.1

MeanMean 104.2104.2

Audit Accuracies on Tenax TAAudit Accuracies on Tenax TAPerchloroethylenePerchloroethylene

CompoundCompound Level (ng)Level (ng) Accuracy (%)Accuracy (%)PerchloroethylenePerchloroethylene 2.22.2 177177

5.55.5 112.6112.6

10.9810.98 110.5110.5

24.224.2 95.295.2

54.954.9 91.291.2

109.8109.8 91.891.8

MeanMean 104.2104.2

Audit Accuracies on Anasorb GCB1Audit Accuracies on Anasorb GCB1TrichloroethyleneTrichloroethylene

CompoundCompound Level (ng)Level (ng) Accuracy (%)Accuracy (%)

TrichloroethyleneTrichloroethylene 2.22.2 122.8122.8

5.55.5 118.9118.9

10.9810.98 99.099.0

24.9624.96 98.998.9

54.954.9 95.795.7

109.8109.8 89.389.3

MeanMean 101.2101.2

Audit Accuracies on Anasorb GCB1Audit Accuracies on Anasorb GCB1PerchloroethylenePerchloroethylene

CompoundCompound Level (ng)Level (ng) Accuracy (%)Accuracy (%)PerchloroethylenePerchloroethylene 5.55.5 95.295.2

10.9810.98 108.8108.8

24.224.2 96.696.6

54.954.9 99.099.0

109.8109.8 94.994.9

MeanMean 100.5100.5

Audit Accuracies on Audit Accuracies on Chromosorb 106Chromosorb 106TrichloroethyleneTrichloroethylene

CompoundCompound Level (ng)Level (ng) Accuracy (%)Accuracy (%)TrichloroethyleneTrichloroethylene 4.44.4 150150

8.88.8 101101

10.9810.98 95.1 95.1

22.022.0 78.8 78.8

MeanMean 106.3 106.3

Audit Accuracies with Tenax TAAudit Accuracies with Tenax TAOther VOCsOther VOCs

CompoundCompound Range tested (ng)Range tested (ng) Mean Accuracy (%)Mean Accuracy (%)

BenzeneBenzene 0.8 – 7.50.8 – 7.5 105.5 (n=32)105.5 (n=32)

1,2-1,2-DichloroethaneDichloroethane

1-241-24 104 (n=19)104 (n=19)

TolueneToluene 0.86 – 220.86 – 22 106.5 (n=29)106.5 (n=29)

Audit Accuracies with Audit Accuracies with Anasorb GCB1Anasorb GCB1

Other VOCsOther VOCs

CompoundCompound Range tested (ng)Range tested (ng) Mean Accuracy (%)Mean Accuracy (%)

BenzeneBenzene 1.0 – 20 1.0 – 20 112 (n=18)112 (n=18)

Ethyl BenzeneEthyl Benzene 1.0 - 241.0 - 24 101 (n=21)101 (n=21)

P-XyleneP-Xylene 1.0 - 221.0 - 22 103.2 (n=20)103.2 (n=20)

Duplicate Precision DataDuplicate Precision DataChlorinated Compounds Sampled on the Ultra II Chlorinated Compounds Sampled on the Ultra II

TCETCE PCEPCE 1,2-DCE1,2-DCE ng pptng ppt ng ppt ng ppt ng ppt ng ppt

Badge A 10.8 108 26.6 183 78.5 950Badge A 10.8 108 26.6 183 78.5 950

Badge B 10.5 105 29.3 201.3 68.6 831Badge B 10.5 105 29.3 201.3 68.6 831

Precision 2.8 %Precision 2.8 % 9.5 % 9.5 % 13.4 % 13.4 %

Criteria of acceptance: ±20 %Criteria of acceptance: ±20 %

Field StudiesField Studies

Field study underway in the State of Field study underway in the State of New YorkNew York

Comparison of diffusive badges and Comparison of diffusive badges and canisters in indoor air canisters in indoor air

Study completed in May 2005; data Study completed in May 2005; data to be tabulated in June, 2005to be tabulated in June, 2005

Conclusions - Diffusive samplers Conclusions - Diffusive samplers provide logistical advantages.provide logistical advantages.

Diffusive SamplersDiffusive Samplers– Small, unobtrusiveSmall, unobtrusive– Low shipping costsLow shipping costs– Easy to useEasy to use– Initial purchase of Initial purchase of

badge <$100badge <$100– DisposableDisposable– No recertification No recertification

costscosts

CanistersCanisters– BulkyBulky– High shipping costsHigh shipping costs– Training necessary Training necessary

for usefor use– Higher costs for Higher costs for

purchase or rentalpurchase or rental– Recertification costsRecertification costs

Conclusions - Diffusive sampler design Conclusions - Diffusive sampler design can be optimized for sub-ppb analysiscan be optimized for sub-ppb analysis..

– A choice of sorbents to optimize A choice of sorbents to optimize collection efficiency. collection efficiency.

– Sorbent cleaning, storage and handling Sorbent cleaning, storage and handling options that avoid contamination options that avoid contamination

– Thermal desorption analysis to permit Thermal desorption analysis to permit sensitivities in the range of 10-25 ppt sensitivities in the range of 10-25 ppt

ConclusionsConclusions The Ultra II diffusive sampler is an The Ultra II diffusive sampler is an

example of a badge that has been example of a badge that has been optimized for low level sampling/analysis optimized for low level sampling/analysis of VOCs.of VOCs.

The badges are easy to use, lightweight The badges are easy to use, lightweight and offer a number of logistical and offer a number of logistical advantages to users.advantages to users.

Initial data show that the badges are Initial data show that the badges are accurate and precise and provide accurate and precise and provide detection limits needed in the field.detection limits needed in the field.