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

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

Number of compounds in

solid phase

: Partition coefficient

Volume of solid phase,

solution, and headspace,
respectively

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

(%)

CB/PDMS

499

4.2

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)

0.432 1.378

1.089 251.05

1.005

0.400 1.391

1.050 254.28

0.925

0.391 1.343

1.054 248.26

0.987

0.380 1.389

1.059 256.25

0.995

0.403 1.402

1.020 255.71

1.015

0.397 1.470

1.010 260.01

1.007

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

100

200

400

600

Time (S)

(

)

100
m

56 m

15 m

1000

2000

3000

time (S)

)

Effect of Distribution Constant on

the Absorption Profile of 0.1 ppm

Analyte

= 831 (p-

Xylene)

= 294

( Toluene)

= 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

100

Compound Number

)

Water Heating
Microwave Heating

Effect of Stirring Rate on the

Extraction of

1 ppm Benzene in Water

200

400

600

Time (S)

)

400 rpm

0 rpm

2,500 rpm

Effect of Agitation Method on the

Extraction of 1 ppm Benzene in

Water

200

400

600

Time (S)

)

No
stirring

Sonication

Magnetic Stirring

Effect of Benzene Concentration on

Extraction by SPME

0.1

100

1000

100

200

300

400

500

600

Time (S)

(

)

= 0.1 ppm

= 10 ppm

= 1 ppm

Benzene

Dioxane

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

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

Concentration

range (ppm)

Y=0.2891X+0.0

Y=0.4913X+0.0

Y=0.2010X+0.0

Y=0.3428X+0.0

Y=17.922X+9.4

0.99

1.00

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

Adsorption Time (minutes)

80°
C

60°
C

50°
C

40°
C

25°
C

Isolation Time Effect on Soybean

Oil Volatile Compounds by SPME

Isolation Time (min)

120

150

°C

Isolation Temperature Effect on

Soybean Oil Volatile Compounds

by SPME

Isolation Temperature (C)

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.

Document Outline