237 / 413
•
7
•
2007 vol. 4
Food, Flavors & Fragrances
Rapid Characterization of Garlic Volatiles
No Sample Prep Required!
Using Headspace GC/MS and an Rxi®-5ms Capillary Column
By Julie Kowalski, Innovations Chemist; Michelle Long, Innovations Chemist;
Jason Thomas, Innovations Chemist; and William Goodman*, GC/MS Applications Specialist
• No sample preparation! Eliminate complicated steps required by other methods.
• Rapid screening of garlic-specific flavor and odor compounds.
• Speedy determination of volatiles profile.
Garlic,
Allium sativum
(L.), has a rich history in
cooking and medicinal use. Recently, garlic supple-
ments have gained popularity for boosting immune
and cardiovascular health. Chromatographic
methods for garlic are used by the dietary supple-
ments industry to detect volatiles, such as sulfide
degradents, that may affect the acceptability of
supplements to the consumer. The headspace gas
chromatography mass spectrometry (HS GC/MS)
method for garlic and garlic powder shown here
requires no sample preparation—making the
bench work simple and fast. Other methods involve
steam distillation, solid phase trapping solvent
exchange, headspace solid phase microextraction,
and simultaneous distillation and solvent extrac-
tion, which can be difficult and time-consuming.
This HS GC/MS analysis was done using a 30m x
0.25mm ID x 1.0µm Rxi®-5ms column and a
PerkinElmer TurboMatrix 40 Trap Headspace
Sampler. Conditions used are shown in the figure
and were set to optimize the comparison. Several
sulfur components were identified including allyl
methylsulfide, 3,3'-thiobis-1-propene, allyl mer-
captan and diallyl disulfide. Diallyl disulfide
appeared to be the dominant component for both
garlic preparations. The fingerprint, or relative
ratios, of the other components were distinct for
fresh garlic and powdered garlic (Figure 1).
Headspace GC/MS is an effective technique for
rapid characterization of garlic and garlic powder
samples. The experimental set-up shown here is
ideal for both screening and low-level trace analy-
sis. This method provides a fast assessment of gar-
lic quality and is applicable to the determination of
low-level sulfur containing compounds from
odorless supplements.
* PerkinElmer
Figure 1
Rapid screening of garlic volatiles—analyze samples in
less than 11 minutes! (Total ion chromatogram)
GC_FF00958
1. allyl methylsulfide
2. 3,3'-thiobis-1-propene
3. allyl mercaptan
4. diallyl disulphide
B. Garlic Powder
GC_FF00959
A. Fresh Garlic
Column: Rxi
®
-5ms, 30m, 0.25mm ID, 1.0µm (cat.# 13453) with a 5m, 0.32mm ID IP deactivated guard
column (cat.# 10044); Sample: A. fresh garlic B. garlic powder
Inj.: split (10:1); Inj. temp.: 220°C; Flow rate: 1.5mL/min.; Oven temp.: 35°C (hold 1 min.) to 220°C @
15°C/min. to 300°C @ 45°C/min.; Det: MS; Scan range: 35-350amu; Ionization: EI; Mode: scan
Headspace Conditions
Instrument: PerkinElmer TurboMatrix 40 Trap Headspace Sampler; Column pressure:15psi (103kPa);
Inj. pressure: 30psi (207kPa); Thermostat time: 15 min.; Vial pressurize time: 1 min.; Withdraw time:
0.2 min.; Injection time: 0.02 min.; Oven temp.: 80°C; Needle temp.: 90°C; Transfer temp.: 110°C
Rxi®-5ms Column (fused silica)
(Crossbond
®
5% diphenyl/95% dimethyl polysiloxane)
ID df (µm)
temp. limits
length cat. #
price
0.25mm 1.00 -60 to 330/350°C 30-Meter 13453
$485
No sample
extraction
required!