diffusive sampling of mvocs by a solid-phase ... · diffusive sampling of mvocs by a solid-phase...
TRANSCRIPT
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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, [email protected]
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OutlineOutlineIntroductionObjectivesResearch StructurePassive SPME SamplerMaterials and MethodsResults and DiscussionsSummaryPerspectives
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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
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
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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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
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