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Diffusive Sampling of Diffusive Sampling of MVOCsMVOCs by a by a SolidSolid--Phase Phase MicroextractionMicroextraction DeviceDevice

Pei-Hua Juan and Shih-Wei Tsai

Institute of Environmental Health, College of Public Health,National Taiwan University, Taipei, Taiwan886-2-33228097r94844005@ntu.edu.tw

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OutlineOutlineIntroductionObjectivesResearch StructurePassive SPME SamplerMaterials and MethodsResults and DiscussionsSummaryPerspectives

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IntroductionIntroduction

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Indoor Air Quality (IAQ)

75%~90% stay in indoor environmentsignificant sources for human exposure to organic air contaminantsbiological hazards-molds, plants, etc.asthma, infection, toxic reaction, SBSmetabolites of Molds- MVOCs (bad odors)

Microbial Volatile Organic Compounds

Mold gives off spores, cellular debris and MVOCs**http://www.wbdg.org/design/env_iaq.php

The pathway of producing MVOCs and toxic metabolites by molds*

*source: Pasanen A.L., Lappalainen S. and Pasanen P.. Volatile organic metabolites associated with some toxic fungi and their mycotoxins. Analyst, 121; 1949-1953 (1996)

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Molds vs. MVOCs

traditional fungi sampling methods-impactor, impinger, centrifugal samplers, filter cassette

molds growing but not produce spores yetspecific molds will grow on the agarunderestimate, can’t know total amount of molds clearly

Molds MVOCsas indicators of active growth of molds inside buildingsknow potentially biological hazards in indoor air in advance

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Common Mold Genus Cladosporium spp.Alternaria spp.Penicillium spp.Aspergillus spp.

Species-Specific MVOCsSome are produced by a number of species, but some are not

2-pentylfuran is specific for Aspergillus fumigatus2-methyl-1-propanol, 3-methyl-1-butanol, 2-heptanone are produced by a number of species

Morphological pictures for four mold genus commonly occur in indoor environment

*http://www.virtualmuseum.ca/~mushroom/English/Species/cladosporiumcladosporioides.htm**http://www.mycology.adelaide.edu.au/gallery/photos/alternaria02.html

***http://webnt.calhoun.edu/distance/internet/Natural/bio220-collier/fungi.htm****http://www.sciencedaily.com/releases/2005/10/051015093046.htm

Cladosporium*

Aspergillus****

Penicillium***

Alternaria**

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Need a New Sampling Method

low [MVOCs]mass collected on the sampling medium

high sampling rateanalytical instrument’s sensitivity

appropriate/rapid sampling time4 hrs ~ 5 hrs[MVOCs] distribution

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ObjectivesObjectives

determination of MVOCsrapid and sensitiveby SPME device?

Research StructureResearch StructureStandards Solution

Optimize Parameters

Standard Curve

GC

Calculate Conc. and SR

Comparison and Assessment of Results

Storage Stability of SPME FiberDetection Limit

Gas Bag Exposure SystemAdsorption Time of SPME Fiber

Adsorption Limit of SPME Fiber

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Passive SPME SamplerPassive SPME Sampler

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SPME Technique

Schematic of sampling with retracted SPME fiber*n(t) = mass of extracted analyte over extraction time t L = length of the coated rod = 1 cm Cg = concentration of analyte in air A = needle opening area = 0.00083 cm2

Dg = gas-phase molecular diffusion coefficient t = sampling time

*source: Jacek A.K. and Inman N.. Sampling and sample-preparation strategies based on solid-phase microextraction for analysis of indoor air. Trends in Analytical Chemistry, 21 (12); 840-850 (2002)

diffusion-based Fick’s First Law

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SPME Sampling Device

Passive SPME Sampler Fick’s First Lawretracted SPME fiber + air bag exposure systemlong sampling time at low concentration

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Materials and MethodsMaterials and Methods

MVOCs + Mold Species

Gas Bag Exposure System

Portable Gas Chromatography, Portable GC

Solid-phase Microextraction, SPME SPME Fiber

2-heptanone2-hexanone1-octen-3-olCla. globosumAlt. alternata

2-methyl-1-propanol

2-heptanone2-hexanone1-octen-3-oPen. chrysogenum

3-methyl-1-butanol

2-heptanone2-hexanone1-octen-3-olPen. expansum

3-methyl-1-butanol2-methyl-1-propanol

2-pentylfuran2-hexanone1-octen-3-olAsp. Fumigatus

3-methyl-1-butanol1-octen-3-olAsp. niger

3-methyl-1-butanol2-methyl-1-propanol

2-heptanone2-hexanone1-octen-3-olAsp. Versicolor

Microbial Volatile Organic CompoundsMold Species

Mold Species and Their Specific MVOCs

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Gas Bag Exposure System

Air Bag*Teflon + dual stainless steel fittings flexible bag systemallow direct insertion of SPME fiber

*http://www.tedlarbag.com/

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Portable GCcolumn: 100% dimethylpolysiloxaneinjector temp.: 250°Cdetector (FID) temp.: 280°Ccarrier gas flow: 10 ml/mintemp. program: (16.5 min)

25°C /min 15°C/min 3°C/min 50°C/min

50°C --> 80°C--> 120°C--> 150°C--> 200°C, 1.5min

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Solid-phase Microextraction, SPME*-

fiber+

holder

(1) 70 μm Carbowax/DVB stableflex(2) 50/30 μm DVB/CAR/PDMS (3) 100 μm PDMS

*http://www.sigmaaldrich.com/Brands/Supelco_Home/Spotlights/SPME_central.html

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Results and DiscussionsResults and Discussions

SPMS Fiber Selection

Mass Collected vs. Conc. × Sampling Time

Theoretical SR vs. Experimental SR

SPMS Fiber Selection

area1 area2area1 area2area1 area2

100 μmPDMS

70 μmCarbowax/DVB

50/30 μmDVB/CAR/PDMS

Chemical Name

24311 -29554 -26145 269(99%*)2-pentylfuran3265 -3441 -2221 -1-octen-3-ol

23741 -19123 -15464 -2-heptanone4843 -4071 -3018 -2-hexanone

19056 -21687 -10926 -3-methyl-1-butanol3551 -4519 -2056 -1-butanol

9297 -11715 -5105 -2-methyl-1-propanol

*Desorption Efficiency (%)= (area1/area1+area2)*100

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Mass Collected vs.

Conc. × Sampling Time

mg

MVOCs Exposure Results from Gas Bag (1)

0

200

400

600

800

1000

1200

1400

0.E+00 2.E+06 3.E+06 5.E+06 6.E+06 8.E+06 9.E+06

conc.*time (mg/cm3*sec)

mas

s col

lect

ed (n

g)

2-methyl-1-propanol1-butanol3-methyl-1-propanol2-hexanone2-heptanone1-octen-3-ol2-pentylfuran

606.30242.52

1442.13163.86934.07419.53226.11

[MVOCs](mg/m3)

mg

MVOCs Exposure Results from Gas Bag (2)

1212.60485.04

2884.25327.72

1868.14839.07452.22

[MVOCs](mg/m3)

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0.E+00 2.E+06 3.E+06 5.E+06 6.E+06 8.E+06 9.E+06 1.E+07 1.E+07 1.E+07 2.E+07 2.E+07

conc.*time(mg/cm3*sec)

mas

s col

lected

(ng)

2-methyl-1-propanol1-butanol3-methyl-1-propanol2-hexanone2-heptanone1-octen-3-ol2-pentylfuran

mg

MVOCs Exposure Results from Gas Bag (3)

2425.19970.08

5768.51655.44

3736.281678.13904.44

[MVOCs](mg/m3)

0

500

1000

1500

2000

2500

3000

3500

4000

0.E+00 3.E+06 6.E+06 9.E+06 1.E+07 2.E+07 2.E+07 2.E+07 2.E+07 3.E+07 3.E+07 3.E+07

conc.*time(mg/cm3*sec)

mas

s col

lected

(ng)

2-methyl-1-propanol1-butanol3-methyl-1-propanol2-hexanone2-heptanone1-octen-3-ol2-pentylfuran

Theoretical SR vs. Experimental SR

*[MVOCs]: 163.86~1442.13 mg/m3

**[MVOCs]: 327.72~2884.25 mg/m3

***[MVOCs]: 655.44~5768.51 mg/m3

(7.74±0.34)E-05(11.80±1.16)E-05(1.13±0.03)E-041.88E-042-pentylfuran

(3.05±0.11)E-05(7.54±0.30)E-05(2.50±0.11)E-041.86E-041-octen-3-ol

(6.77±0.29)E-05(8.63±0.42)E-05(0.85±0.04)E-041.99E-042-heptanone

(4.45±0.21)E-05(6.52±0.24)E-05(0.81±0.03)E-042.16E-042-hexanone

(10.90±0.54)E-05(12.00±0.60)E-05(1.44±0.06)E-042.32E-043-methyl-1-butanol

(7.28±0.25)E-05(14.60±0.53)E-05(2.29±0.11)E-042.58E-041-butanol

(7.33±0.35)E-05(8.74±0.40)E-05(1.27±0.06)E-042.58E-042-methyl-1propanol

(cm3/s)***(cm3/s)**(cm3/s)*(cm3/s)

Experimental Sampling Rate

Experimental Sampling Rate

Experimental Sampling Rate

Theoretical Sampling RateChemicals

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SummarySummary

passive sampling method is developedSPME Fiber- 70 μm Carbowax/DVBExperimental Sampling Ratelower conc. > higher conc.

competitive adsorption and displacement effects?

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PerspectivesPerspectivesKnow more about the effect of

lower [MVOCs]temperaturerelated humidity

Emission patternsampling time

For further applicationsmold species/concentration vs. their [MVOCs]examining the fingerprints of mold species

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AcknowledgementAcknowledgement

NSC 94-2314-B-002-313Taiwan