1

Session 2 – Analytical IssuesSession 2 – Analytical Issues

Mercury Speciation WorkshopMercury Speciation Workshop

330 Nantucket Blvd. Toronto, Canada M1P 2P4330 Nantucket Blvd. Toronto, Canada M1P 2P4

Rev 1.10 Nov 2003

ekran Inc. ekran Inc.

2

Issues in Session TwoIssues in Session Two

11 Do 1130 & 1135 work in the Arctic ?Do 1130 & 1135 work in the Arctic ?22 What Species do denuders measure ? What Species do denuders measure ? 33 What does a Model 2537A measure ?What does a Model 2537A measure ?44 Precision & Accuracy of methodPrecision & Accuracy of method55 Effects of sodalime trapEffects of sodalime trap66 Calibration for RGM & HgPCalibration for RGM & HgP77 Denuder coating techniquesDenuder coating techniques88 RPF refill techniquesRPF refill techniques

3

Do Do the Model the Model 1130 & 1135 Work1130 & 1135 Work in the in the ArcticArctic??

4

CaveatsCaveats

The following is The following is notnot based upon any based upon any actual arctic measurementsactual arctic measurements

There is currently no reliable RGM There is currently no reliable RGM calibration source that would work under calibration source that would work under those conditionsthose conditions

Tekran doesn’t go up there oftenTekran doesn’t go up there often We don’t have an environmental test We don’t have an environmental test

chamberchamber

5

Tests at TekranTests at Tekran

Tests were continuously run during the year it Tests were continuously run during the year it took to deliver first Model 1130-P prototypes took to deliver first Model 1130-P prototypes (May 1998)(May 1998)

Initial tests used packed cartridgesInitial tests used packed cartridges Subsequent tests used thermal denuderSubsequent tests used thermal denuder

Tests were run using outdoor air in TorontoTests were run using outdoor air in Toronto Summer:Summer: +30° C, (typical moist summer air)+30° C, (typical moist summer air) Winter:Winter: -20° C, (typical dry winter conditions) -20° C, (typical dry winter conditions)

Method worked well under full seasonal rangeMethod worked well under full seasonal range

6

Temp Dependent Denuder VariablesTemp Dependent Denuder Variables

Diffusion coefficient of HgClDiffusion coefficient of HgCl22

Low temps could Low temps could reducereduce capture efficiency capture efficiency Actual gas volume of sample (p,v)Actual gas volume of sample (p,v)

Affects residence time in denuderAffects residence time in denuder Low temps Low temps increaseincrease residence time residence time

Gas is pre-heated by impactor and Gas is pre-heated by impactor and denuder inletdenuder inlet

Approx inlet volume is 80 mlApprox inlet volume is 80 ml Heating residence time is ~0.45 sec. (at 10 l/m)Heating residence time is ~0.45 sec. (at 10 l/m) Actual gas temp at denuder inlet will not be Actual gas temp at denuder inlet will not be

close to -40close to -40°° C C

7

Main Difference with Arctic AirMain Difference with Arctic Air

The major difference between arctic The major difference between arctic air and temperate air is the air and temperate air is the moisturemoisture content of the aircontent of the air

After heating, the air will be After heating, the air will be veryvery dry dry

Does the 1130 capture RGM under Does the 1130 capture RGM under low humidity conditions?low humidity conditions?

8

Tests by Frontier GeosciencesTests by Frontier Geosciences

Two prototype 1130’s purchased by Two prototype 1130’s purchased by Florida DEP were extensively tested by Florida DEP were extensively tested by Eric Prestbo in 1998Eric Prestbo in 1998

Contract funded by Tom Atkeson of FL DEPContract funded by Tom Atkeson of FL DEP Formal report never issuedFormal report never issued Results were presented at several Results were presented at several

conferences and incorporated into Landis et. conferences and incorporated into Landis et. al. (ES&T, 2002)al. (ES&T, 2002)

9

Relevant FL DEP TestsRelevant FL DEP Tests

Tests were done using:Tests were done using: Nitrogen from a dewarNitrogen from a dewar Ambient airAmbient air

Sample gas created from a dewar Sample gas created from a dewar was extremely drywas extremely dry

No significant differences in capture No significant differences in capture efficiency were detected between efficiency were detected between very dry gas sample and ambient very dry gas sample and ambient samplessamples

10

Arctic TestsArctic Tests

Alert: Bill Schroeder ran two different Alert: Bill Schroeder ran two different systems in parallelsystems in parallel

Arctic PyrolyzerArctic Pyrolyzer No inlet filterNo inlet filter Large pyrolyzer, 900 °C with lengthy Large pyrolyzer, 900 °C with lengthy

residence timeresidence time Feeds into a Model 2537AFeeds into a Model 2537A Expected to yield total atmospheric mercury Expected to yield total atmospheric mercury

((TAMTAM) (both gaseous and particulate forms)) (both gaseous and particulate forms)

Model 1130/1135/2537AModel 1130/1135/2537A

11

ResultsResults

During non-depletionsDuring non-depletions Fairly good agreement between the methodsFairly good agreement between the methods HgHg00 (GEM) slightly lower in 1130/35 system (GEM) slightly lower in 1130/35 system

During MDEsDuring MDEs Some differences, typically 20-30% with Some differences, typically 20-30% with

pyrolyzer being higher (personal pyrolyzer being higher (personal communication S. Steffen, B. Schroeder)communication S. Steffen, B. Schroeder)

Shows that there is no gross failure of the Shows that there is no gross failure of the 1130/1135 method in the Arctic, even 1130/1135 method in the Arctic, even during MDEsduring MDEs

12

When No RGM or TPM PresentWhen No RGM or TPM Present

Pyro TAM ~0.2 ng/mPyro TAM ~0.2 ng/m33 higher than higher than GEM measured through 1130/35GEM measured through 1130/35

There may be slight contamination in There may be slight contamination in pyrolyzer systempyrolyzer system

Material in pyro chamberMaterial in pyro chamber Downstream heated lineDownstream heated line

There may be scavenging in 1130/35There may be scavenging in 1130/35 RPF, downstream filter or internal linesRPF, downstream filter or internal lines Heated line or fittings around PMHeated line or fittings around PM

13

Possible Reasons - GEMPossible Reasons - GEM

Should review Arctic QA/QC data to Should review Arctic QA/QC data to determine:determine:

Do Do TAMTAM values decrease after cleaning values decrease after cleaning of the pyrolyzer and downstream heated of the pyrolyzer and downstream heated line & fittings?line & fittings?

Have zero checks and manual injection Have zero checks and manual injection tests of entire pyrolyzer system revealed tests of entire pyrolyzer system revealed any problems?any problems?

14

Possible Tests - GEMPossible Tests - GEM

CouldCould perform external zero and Hg perform external zero and Hg00 addition system addition system testtest on 1130/35 on 1130/35

Requires 10 l/m zero air sourceRequires 10 l/m zero air source Manual injection source & syringe (large Manual injection source & syringe (large

volume syringe: 100-250 volume syringe: 100-250 µµl)l) Must Must first first perform accurate flow rate perform accurate flow rate

tests on both 2537A and 1130 pump!tests on both 2537A and 1130 pump! Required to determine what fraction of Required to determine what fraction of

injected Hg will disappear through PMinjected Hg will disappear through PM Tricky test !Tricky test !

15

Other Reasons for DifferencesOther Reasons for Differences

Two devices are measuring slightly Two devices are measuring slightly different things:different things:

Pyro measures Pyro measures totaltotal particulate loading particulate loading 1130/35 measures fine fraction particulates (1130/35 measures fine fraction particulates (< <

2.5 2.5 µµmm)) Difference could be legitimate Difference could be legitimate

Some mercury may be in coarse particulate Some mercury may be in coarse particulate fractionfraction

Could also be losses of RGM on inlet Could also be losses of RGM on inlet surfacessurfaces

Dirty impactor surfacesDirty impactor surfaces Insufficient heatingInsufficient heating

16

What Species Do Thermally What Species Do Thermally Regenerated KCl Denuders Regenerated KCl Denuders

Measure?Measure?

17

Mercury Chloride - HgClMercury Chloride - HgCl22

Compound most often Compound most often used as a used as a surrogate for “RGM”surrogate for “RGM”

Reasonable choice since it’s believed Reasonable choice since it’s believed to be created by many industrial to be created by many industrial sourcessources

Believed to be the bulk of RGM Believed to be the bulk of RGM loadingsloadings

18

Mercury Chloride - HgClMercury Chloride - HgCl22

Extensively tested by TekranExtensively tested by Tekran Major pain to work withMajor pain to work with

Extremely “sticky”Extremely “sticky”

Regenerable KCl media had >98% Regenerable KCl media had >98% capture efficiencycapture efficiency

Initial work with KCl coated quartz chipsInitial work with KCl coated quartz chips Subsequently validated using denudersSubsequently validated using denuders

19

Mercury Iodide – HgIMercury Iodide – HgI22

Originally tested as a substitute for Originally tested as a substitute for HgClHgCl22

Hoped that it would be easier to work Hoped that it would be easier to work withwith

Turned out to be exactly as much of a Turned out to be exactly as much of a painpain

Behaved the same as HgClBehaved the same as HgCl22 with a with a

capture efficiency: >98%capture efficiency: >98%

20

Monomethyl mercury chloride – Monomethyl mercury chloride – CHCH33HgCIHgCI

Tested by Jonas Sommar (Sweden)Tested by Jonas Sommar (Sweden) Tests pre-dated thermal methodTests pre-dated thermal method Used tubular denuder with wet Used tubular denuder with wet

extraction & digestionextraction & digestion Reported a capture efficiency: >94%Reported a capture efficiency: >94%

(In comparison to 98% for HgCl(In comparison to 98% for HgCl22))

Don’t have a publication referenceDon’t have a publication reference

21

Further Testing NeededFurther Testing Needed

EPA NERL (Matt Landis, Bob EPA NERL (Matt Landis, Bob Stevens) are planning on testing a Stevens) are planning on testing a wide variety of mercury compounds wide variety of mercury compounds for capture efficiencyfor capture efficiency

22

What does a Model 2537A actually What does a Model 2537A actually measure ?measure ?

Is there a simple answer ?Is there a simple answer ?

23

What We KnowWhat We Know

The Model 2537A will respond to The Model 2537A will respond to HgClHgCl22 that is presented to the that is presented to the

cartridges cartridges Ontario Hydro, 1995 (?)Ontario Hydro, 1995 (?) Had to bypass all front end components Had to bypass all front end components

to get HgClto get HgCl22 into the cartridges into the cartridges

We We can’tcan’t claim that the 2537A is an claim that the 2537A is an elementalelemental Hg analyzer Hg analyzer

24

Transport IssuesTransport Issues

HgClHgCl22 does not transport well through does not transport well through sample lines or filterssample lines or filters

Will stick onto the materialsWill stick onto the materials MayMay come off later depending on come off later depending on

factors such as:factors such as: TemperatureTemperature HumidityHumidity Composition of sampleComposition of sample ERG & EPA (1997-98)ERG & EPA (1997-98)

25

Under Arctic ConditionsUnder Arctic Conditions

Model 2537A functions basically as Model 2537A functions basically as an elemental Hg analyzeran elemental Hg analyzer

Evidence: MDE’s were originally Evidence: MDE’s were originally discovered by Env. Canadadiscovered by Env. Canada

2537A recorded very low values2537A recorded very low values We now know that lots of RGM was We now know that lots of RGM was

present during many of those eventspresent during many of those events

26

Precision & AccuracyPrecision & Accuracy

Caveats for duplicate instrument Caveats for duplicate instrument runsruns

27

Tests with Prototype 1130’sTests with Prototype 1130’s

Our oOur outdoor air was brought in utdoor air was brought in through a 4” plastic pipe using a 700 through a 4” plastic pipe using a 700 l/m blowerl/m blower

Both units ran from same pipeBoth units ran from same pipe We do not claim that sample We do not claim that sample

contained true outdoor RGM levelscontained true outdoor RGM levels Got good agreement between unitsGot good agreement between units

28

Side by side TestsSide by side Tests

Indoor air was simply taken in by the Indoor air was simply taken in by the two 1130’s mounted side by sidetwo 1130’s mounted side by side

Not as good agreement for RGM. Not as good agreement for RGM. Why?Why?

1.1. Denuders more precise at lower Denuders more precise at lower concentrationsconcentrations

2.2. Outdoor air works better than indoor airOutdoor air works better than indoor air

3.3. Sampling wasn’t from a common Sampling wasn’t from a common manifoldmanifold

29

Early Results - TorontoEarly Results - Toronto RGM Comparison: SN:001, SN:002

May-23 12:00 May-24 00:00 May-24 12:00 May-25 00:00 May-25 12:00 May-26 00:00 May-26 12:00

1998

0

10

20

30

40

50

60

RG

M (

pg

/m3

)

RGM SN:001 (y)

RGM SN:002 (x)

SuccessiveDesorption (Blank Test)

Denuder Clean

Operation

Outdoor Air(Sampling through long inlet manifold)

Indoor Airy = 1.0595x - 0.5374

R2 = 0.9959

30

Early Results - TorontoEarly Results - TorontoElemental Mercury: SN:001 & SN:002

0

2

4

6

8

10

12

14

16

18

May-23 12:00 May-24 00:00 May-24 12:00 May-25 00:00 May-25 12:00 May-26 00:00 May-26 12:00

Date

Hg0 (

ng

/m3 )

Hg0 SN:001Hg0 SN:002

Outdoor Air

Indoor Air

31

Duplicate InstrumentsDuplicate Instruments

Running two instruments side by side Running two instruments side by side is not trivialis not trivial

Must be sampling Must be sampling exactlyexactly the same the same airair

Even minor differences in location will Even minor differences in location will have a large impacthave a large impact

Have seen this with 2537A for yearsHave seen this with 2537A for years Much more of an effect with RGM/HgPMuch more of an effect with RGM/HgP

32

CaveatsCaveats

Sampling manifold issuesSampling manifold issues First instrument in chain will contaminate sample First instrument in chain will contaminate sample

manifold when blowing back zero air during manifold when blowing back zero air during desorptiondesorption

Precise syncing will help, but not eliminate this problemPrecise syncing will help, but not eliminate this problem

Transport of RGM & HgP along manifoldTransport of RGM & HgP along manifold Effect of intrusion by sampling inletsEffect of intrusion by sampling inlets

Scavenging/contaminationScavenging/contamination

Isokinetic sampling if monitoring particulatesIsokinetic sampling if monitoring particulates

33

CaveatsCaveats

Instrument flow rates are critical!Instrument flow rates are critical! Must calibrate all 2537A and 1130 Must calibrate all 2537A and 1130

MFM’s before running any testsMFM’s before running any tests

34

Effects of Sodalime TrapEffects of Sodalime Trap

35

Effects of Sodalime TrapEffects of Sodalime Trap

Works well in most casesWorks well in most cases Bad sodalime can either scavange or Bad sodalime can either scavange or

augment mercury from sampleaugment mercury from sample Good sodalime can go bad simply by Good sodalime can go bad simply by

being stored after openingbeing stored after opening Must be kept above dew point of Must be kept above dew point of

sample airsample air

36

Calibration for RGM & HgP ?Calibration for RGM & HgP ?

37

Calibration - RGMCalibration - RGM

Very difficult to get long term stability Very difficult to get long term stability in labin lab

Even harder in the fieldEven harder in the field Likely to be used as a check, rather Likely to be used as a check, rather

than as an actual calibration sourcethan as an actual calibration source

38

Calibration - HgPCalibration - HgP

Even more difficult !Even more difficult ! Some issues:Some issues:

Picogram amounts requiredPicogram amounts required Controlling size distributionControlling size distribution Sample introduction Sample introduction

39

Denuder Coating Techniques ?Denuder Coating Techniques ?

40

Two techniquesTwo techniques

Original super-saturated methodOriginal super-saturated method EPA methodEPA method

41

RPF Refill Techniques ?RPF Refill Techniques ?

42

RPF Standard TechniqueRPF Standard Technique

There is none !There is none !

43

End of Session 2End of Session 2