Solid Phase Microextraction

Analyses of Flavor Compounds

in Foods

David B. Min

Department of Food Science and

Technology

The Ohio State University

Columbus Ohio

Instrumental Analysis of Volatile

Compounds

• Static headspace

analysis

• Dynamic headspace

analysis

• Solid phase

microextraction

Detection Limits and

Reproducibility of Organic Volatile

Compounds in Water

Technique Detection

Limit with FID
(ppb)

Coefficient of
Variation (%)

SPME

Static
Headspace

Dynamic
Headspace

0.05-0.2

5- 10

0.005-0.05

1-3

1-3

4-8

Definition of Solid Phase

Microextraction

Equilibrium partitioning of the
compounds between the coating
fiber and sample or headspace.

A technique that uses a short, thin,
solid rod of fused silica, coated with
absorbent polymer for extraction of
volatile compounds

Diagram of SPME

Extraction

Direct sampling SPME

Headspace SPME

Principles of Headspace

SPME

K

fh

V

f

V

s

C

o

K

fh

V

f

+

K

hs

V

h

+

V

s

n

f=

n

f

:

Number of compounds in

solid phase

K

: Partition coefficient

K

fh

=

V

f

,

V

s

,

V

h

:

Volume of solid phase,

solution, and headspace,
respectively

C

o

:

Initial concentration of

compounds in the solution

Concentration of
coating

Concentration of headspace

Plunger

Barrel

Gauge

Water bath

Solid Phase

SPME Analysis of Volatile

Compounds

Types of Solid Phases

•
CB/PDMS:Carboxen/Polydimethylsiloxa
ne

• PDMS: Polydimethylsiloxane
• CW/DVB: Carbowax/Divinylbenzene
• PA: Polyacrylate.

Effects of Different Solid Phases

on the Hexanal Analysis in

Soybean Oil

Mean

CV

(%)

CB/PDMS

499

4.2

PA

739

7.2

PDMS

966

3.2

CW/DVB 1,520

2.9 (10.7)

CV: Coefficient Variation (%) for n =5

Significant difference (P<0.05)

Hexanal Peak in Electronic Count

SPME Reproducibility of Major Flavor

Compounds in Orange Juice

Replicates

Ethyl butyrate

(ppm)

-

Pinene
(ppm)

Octanal
(ppm)

Limone
ne
(ppm)

Decana
l (ppm)

1

0.432 1.378

1.089 251.05

1.005

2

0.400 1.391

1.050 254.28

0.925

3

0.391 1.343

1.054 248.26

0.987

4

0.380 1.389

1.059 256.25

0.995

5

0.403 1.402

1.020 255.71

1.015

6

0.397 1.470

1.010 260.01

1.007

SD

0.017 0.042

0.029 4.130

0.033

CV(%)

4.36

3.00 2.71 1.63

3.32

ave

0.400 1.395

1.047 254.26

1.989

Effect of Injection Temperature on

Chromatograms

of Soybean Oil Volatile Compounds

230 °C

250 °C

Effect of Coating Thickness on the

Absorption for the Extraction of 0.1

ppm Benzene

0

20

40

60

80

100

0

200

400

600

Time (S)

M

a

s

s

(

n

g

)

100
m

56 m

15 m

0

5

10

15

20

25

30

0

1000

2000

3000

time (S)

M

as

s

(n

g

)

Effect of Distribution Constant on

the Absorption Profile of 0.1 ppm

Analyte

K

fs

= 831 (p-

Xylene)

K

fs

= 294

( Toluene)

K

fs

= 125

( Benzene)

Effect on Sample Temperature on the GC

Chromatogram of Compounds

Extracted at 25 °C

Extracted at 130
°C

Extracted at 200
°C

Effect of Water and Microwave Heating on the

chromatograms of Headspace Polyaromatic

Compounds

1, naphthalene: 2, acenaphthylene: 3, acenaphthalene: 4, fluorene:
5,anthracene

0

20

40

60

80

100

1

2

3

4

5

Compound Number

M

as

s

E

xt

ra

ct

ed

(n

g

)

Water Heating
Microwave Heating

Effect of Stirring Rate on the

Extraction of

1 ppm Benzene in Water

0

10

20

30

40

0

200

400

600

Time (S)

M

as

s

(n

g

)

400 rpm

0 rpm

2,500 rpm

Effect of Agitation Method on the

Extraction of 1 ppm Benzene in

Water

0

10

20

30

40

0

200

400

600

Time (S)

M

as

s

(n

g

)

No
stirring

Sonication

,

Magnetic Stirring

Effect of Benzene Concentration on

Extraction by SPME

0.1

1

10

100

1000

0

100

200

300

400

500

600

Time (S)

M

a

s

s

(

n

g

)

C

s

= 0.1 ppm

C

s

= 10 ppm

C

s

= 1 ppm

Benzene

Dioxane

N

o

rm

a

li

z

e

d

F

ID

R

e

s

p

o

n

s

e

No Salt

Sodium Chloride
Sodium Sulfate

PotassiumCarbonate

Effect of Salts on the Extraction of

Volatile Compounds by SPME

Matrix Effect on the Extraction

of Alcohols by SPME

Cltronellol

Geranlol

D

e

te

c

to

r

R

e

s

p

o

n

s

e

Water

water-salt

12% Ethanol

12% Ethanol-salt

Gas Chromatogram of Orange

Juice Flavor by SPME Headspace

Sampling

Regression Equations between Flavor

Compounds (ppm) and GC Peak Areas

Compound
s

Ethyl butyrate

-

Pinene

n-
Octanal

Limone
ne

Decanal

Regression Eq

R

2

Concentration

range (ppm)

Y=0.2891X+0.0

15

Y=0.4913X+0.0

03

Y=0.2010X+0.0

66

Y=0.3428X+0.0

92

Y=17.922X+9.4

62

0.99

1.00

0.99

0.99

0.99

0.1-
1.2

0.1-
1.3

0.1-
1.1

0.2-
2.0

20-50

Y: Compound part per million, X:Electronic counts of
GC peak area

Effects of Temperature and Time on the

Equilibrium of Flavor Compounds

Between the SPME Coating and the

Headspace of Orange Juice

0

5

10

15

20

25

30

0

10

20

30

40

50

60

Adsorption Time (minutes)

F

ID

r

e

s

p

o

n

s

e

80°
C

60°
C

50°
C

40°
C

25°
C

Isolation Time Effect on Soybean

Oil Volatile Compounds by SPME

40

Isolation Time (min)

R

e

la

ti

v

e

P

e

a

k

S

iz

e

0

10

20

30

0

30

60

90

120

150

60

45

35

°C

°C

°C

Isolation Temperature Effect on

Soybean Oil Volatile Compounds

by SPME

Isolation Temperature (C)

R

e

la

ti

v

e

P

e

a

k

S

iz

e

0

5

10

15

20

25

30

35

45

60

PV 1

PV 50

Chromatograms of Volatile Compounds of

Soybean Oil by SPME

Volatile Compounds in the Headspace of

Soybean Oil by SPME-GC-MS

Pentane

1.38

3.65

Pentanal

2.06

5.31

Hexanal

3.84

23.5

2-Butanone

3.97

9.09

Heptanal

5.90

2.70

2-Heptenal

6.45

4.76

2-Pentylfuran

8.40

4.77

2,4-Heptadienal

10.99

5.04

t-2-Octenal

11.53

3.37

Nonanal

14.00

2.86

t-2-Nonenal

14.29

0.55

2-Decenal

18.69

34.3

Compounds

Retention Time

(min)

Relative
(%)

Effect of Isolation Temperature on Corn Oil

Volatile Compounds by SPME

25°C

45°C

60°C

35°C

Volatile Compounds in the

Headspace of Corn Oil by SPME-

GC-MS

Pentane

1.29

13.03
Pentanal

1.88

5.52
Hexanal

3.62

5.39
Heptanal

5.36

1.83

2-Heptenal

6.21

29.52

2-Pentylfuran

8.59

2.53

2,4-Heptadienal

10.88

7.69
t-2-Octenal

11.51

18.07

Nonanal

13.88

6.27
t-2-Nonenal

14.23

1.33

2-Decenal

18.61

4.93

t,t-2,4-Decadienal

20.20

1.17

t,c-2,4-Decadienal

20.70

2.71

Compounds

Retention Time

(min)

Relative
(%)

Chromatograms of Soybean Oil and

Corn Oil

Soybean Oil

Corn Oil

Factors for the Sensitivity of

Solid Phase Microextraction

• Solid Phase Thickness
• Extraction Temperature and Time
• Sample Concentration
•Agitation Rate and Type
• Direct sampling versus Headspace

Sampling
• Types of Solid Phases
• Types Salts and Matrix of Foods
• Optimum Ratio of Sample to Headspace

Volume
• Sampling Vial Sizes

Conclusion

• Reproducible
• Economic
• Simple
• Sensitive

The SPME-GC is a

for the analysis of volatile
compounds in most foods.