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Analysis of VOCs in complex

samples

John R. Dean

Northumbria UniversityEmail: [email protected]

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O

O

Ethylbutanoate

O

1-Octen-3-one

O S

Methional

O

OH

Isovaleric acid

(3-methylbutanoic acid)

O

OH

2-Methoxyphenol

(Guaicaol)

OH

2-Phenylethanol

NH

3-Methylindole

(skatole)

VOCs

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O

O

Ethylbutanoate

Fruity, apple O

1-Octen-3-one

Mushroom, metallic

O S

Methional

Boiled potato

O

OH

Isovaleric acid

(3-methylbutanoic acid)

Sweaty

O

OH

2-Methoxyphenol

(Guaicaol)

Spicy, burnt, sweetOH

2-Phenylethanol

Wine

Roses, sweet

NH

3-Methylindole

(skatole)

Faecal

VOCs(60)

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Malodour on Laundry

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Trap

To GC

Purge gas

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Consumer washing machinesDirect olfactive

analysisDHS-GC-O/MS

Swabs of surfaces

within machines

Fabrics washed inmachines

HS-SPME-GC-O/MS Microbiological

testsHS-SPME-GC-O/MS

Microbiological

tests

Overview of experimental

Direct olfactive

analysis

Microbiological

tests

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analysisDHS-GC-O/MS

Swabs of surfaces

within machines

Fabrics washed inmachines



Microbiological

tests


Direct olfactive

analysis

Microbiological

tests

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Machine Definition Malodour? Make and Model Cycle chosen

1 Brand new washing

machine

No Hotpoint Aquarius

WF541 1400

Cold wash, 800rpm, Woollen,

52 mins

2 Used WashingMachine

No Miele HoneycombCare W3622

Cold wash, 800rpm, Woollen,39 mins

3 Consumer washing

machine

(Consumer 1)

Yes (Grade 8) Bosch Exxcel 1400

express, maxx

freedom performance

Cold wash, 800rpm, Woollen

(with wash plus), 50 mins

4 Consumer washingmachine

(Consumer 2)

Yes (Grade 6) Hoover OptimaOPH714D 7kg 1400 Cold wash, 800rpm, Woollen,59 mins

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Machine Definition Malodour? Make and Model Cycle chosen

1 Brand new washing

machine

No Hotpoint Aquarius

WF541 1400

Cold wash, 800rpm, Woollen,

52 mins

2 Used WashingMachine

No Miele HoneycombCare W3622

Cold wash, 800rpm, Woollen,39 mins

3 Consumer washing

machine

(Consumer 1)

Yes (Grade 8) Bosch Exxcel 1400

express, maxx

freedom performance

Cold wash, 800rpm, Woollen

(with wash plus), 50 mins

4 Consumer washingmachine

(Consumer 2)

Yes (Grade 6) Hoover OptimaOPH714D 7kg 1400 Cold wash, 800rpm, Woollen,59 mins

Olfactive Grade Machine 1 Machine 2 Machine 3 Machine 4

Drawer 0 0 4 2

Rubber seal/Drum 0 1 8 6

Sump 0 2 8 6

Coin Trap 0 0 4 3

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No. of colony

forming units (k)Machine 1 Machine 2 Machine 3 Machine 4

Drawer 0 0 39.9

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No. of colony

forming units (k)Machine 1 Machine 2 Machine 3 Machine 4

Drawer 0 0 39.9

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analysisDHS-GC-O/MS

Swabs of surfaces

within machines

Fabrics washedin machines



Microbiological

tests


Direct olfactive

analysis

Microbiological

tests

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Olfactory grading of fabrics /

Washing machine 3 (n = 3)

0

1

2

3

4

5

6

7

8

9

10

0 10 20 30 40 50 60

Olfactorygrading(

arbitrary

scale)

Time (hours)

Terry-towel

Fleece

Washing machine

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DHS-GC-O/MS of rubber

seal of washing machine 3

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Examples of peak identification*

peaknumber GC-O GC-MS

11 Floral, fragrant -pinene

14 cheese, sulphur dimethyl trisulphide

22 burnt, fatty, long-lasting nonanal

28 sweet, floral, slightly burnt decanal

* Known perfume components (e.g. Eucalyptol) and surfactants (at

long retention times) were also detected

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analysisDHS-GC-O/MS

Swabs of surfaces

within machines

Fabrics washed

in machines



Microbiological

tests


Direct olfactive

analysis

Microbiological

tests

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Microbiological identification of

bacteria from washing machines

and

MALDI-TOF-MS

Analytical Profile Index (API) strips

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Fabrics versus washing machines

62 different microbes identified from 4

washing machines

45 different microbes identified from washed

fabrics

Majority of microbes were from

environmental sources i.e. not pathogenic

bacteria.

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HS-SPME-GC-MS identification of

VOCs from bacteria from washing

machines and fabrics

10 VOCs commonly identified from bacteria from

washing machines and fabrics (fleece and Terry-

towel).

Dimethyl disulphide; 3-methyl-1-butanol; 2,4-

dithiapentane; dimethyl trisulphide; 2-tridecanone;indole; 2-phenylethanol; isovaleric acid; isobutryric

acid; and, 1-undecene.

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HS-SPME-GC-MSofShewanel la pu trefaciens

from washing machine

Peak identifications:(1)dimethyl disulphide; (2) siloxane; (3) 2,4-dithiapentane; (4) siloxane;

(5) dimethyl trisulphide; (6) unknown; (7) 2-nonanone; (8) 2-undecanone; (9) isovaleric acid

NOTE: Shewanel la putrefaciensis a Gram-negative bacteria found in

marine environments; it has a rotting fish smell.

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Conclusions

Evidence obtained that points to a possible

link that contamination of fabrics occurs from

washing machines.

Based on the identification of the same bacteria in

WM rubber seal and on fabrics.

Potential VOC markers for both high levels of

bacteria and malodour in washing machines aredimethyl disulphide and dimethyl trisulphide.

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Gas Chromatography-Ion Mobility Spectrometer

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Multi capillary column

The MCC comprises a stainless steel tube, 20 cm x 3 mm ID,

containing approximately 1200 parallel capillary tubes, 40 m ID,

coated with 0.2 m film thickness of stationary phase.

Stationary phases: Carbowax 20M (polyethylene glycol) and OV-5

(5% - diphenyl, 95% - dimethylpolysiloxane)

http://www.mcc-chrom.com/

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Driftgas inlet

Ionisationregion

Drift region

Faraday plate

Outlet

Sample inlet

Electrical field

BN-Shutter

+

++

++

++

+

+

Working principle of the IMS

IMS Drift Tube

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Driftgas inlet

Ionisationregion

Drift region

Faraday plate

Outlet

Sample inlet

Electrical field

BN-Shutter

+

+++

+

+

+

+

+

+

+

+


IMS Drift Tube

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Driftgas inlet

Ionisation

region

Drift region

Faraday plate

Outlet

Sample inlet

Electrical field

BN-Shutter

+

+++

++

+

+

+

+

+

+

Signal

Drift time / ms

+


IMS Drift Tube

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Drift time (ms)

Retent

iontime(s)

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Formation of Reactant Ion Peak (RIP):

N2 N2+ + e-

N2+ + (H2O)m H

+(H2O)m-1 + OH- + N2

H+(H2O)m-1 H3O+(H2O)m-2

RIP

Formation of monomer, dimer and trimer:

X + H3O+(H2O)m-2 XH+(H2O)m-3 + H2O

[XH+(H2O)m-3 XH3O+(H2O)m-4]

X + XH3O+(H2O)m-4 X2H

+(H2O)m-5 + H2O

[X2H+(H2O)m-5 X2H3O

+(H2O)m-6]

X + X2H3O+(H2O)m-6 X3H

+(H2O)m-7 + H2O

[X3

H+(H2

O)m-7

etc]

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Drift time (ms)

Retent

iontime(s)

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0

50

100

150

200

250

300

350

400

6 7 8 9 10 11 12 13 14 15

Retentiontim

e(s)

Drift time (ms)

2-Dimensional map of 14 VOCs

4-methylvaleric acid

dimethyl trisulfide

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Compounds in mixture: ethylbutanoate, octanal, E-2-octanal, E-2-nonanal,

(E,E)-2,4-nonadienal, (E,E)-2,4-decadienal, 1-decanol, 3-methylindole, 4-

methoxybenzaldehyde, guaiacol, 2-phenylethanol, 1-dodecanol

Column: Carbowax (polar) Incubation time: 10 min

Carrier gas flow rate: 150 mL/min Incubation temperature: 95 oC

Drift gas flow rate: 500 mL/min Sample in Vial: 2 mL

Column temperature: 30 - 80 oC Injection volume: 2.2 mL

IMS temperature: 45 oC Measurement run time: 11 20 mins

RIP voltage: Positive Syringe temperature: 95 oC

Trigger duration: 100 s

Electric field along IMS tube: 2 kV

Typical operating conditions

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Acknowledgements

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