3. Helium 5.0 or higher purity.
4. A À80
C freezer for sample storage.
5. A 100–1000 μL micropipette.
6. Gas Chromatograph coupled to a mass spectrometer (see Note
6).
7. Combi-PAL autosampler adapted for SPME, including a Fiber
Conditioning Module (see Note 7).
8. A DB-5 ms GC capillary column (60 m length, 0.25 mm
internal diameter, 1.0 μm film thick).
3 Methods
3.1 Volatile
Apocarotenoid Method
3.1.1 Sampling
Procedure
1. Clean the Citrus fruit surface with deionized water and carefully dry with a paper cloth.
2. Cut the fruit transversally in two pieces and extract the juice
with a hand juicer (see Note 8).
3. Take 2 mL of the juice with a micropipette and transfer to the
bottom of a 10 mL headspace vial.
4. Close the vial tightly and freeze immediately.
5. Store at À80
C until analysis (see Note 9).
3.1.2 Sample
Preparation
1. Incubate the vial for 10 min at 20
C in a water bath to allow
the sample to thaw.
2. Locate the vial in the autosampler tray and analyze immediately
(see Note 10).
3.1.3 HS-SPME GC-MS
Analysis
1. Preincubate de vials at 50
C for 10 min with 500 rpm agitation
by means of the CombiPAL autosampler.
2. Insert the SPME holder in the vial, and expose the 50/30 μm
DVB/CAR/PDMS fiber to the headspace for volatile extraction at 50
C for 20 min with 500 rpm agitation.
3. Desorb the volatiles by introducing the fiber in the injection
port at 250
C for 1 min in splitless mode.
4. Clean the fiber in the Fiber Conditioning Module with Helium
flow at 250
C for 5 min to prevent cross-contamination.
5. Gas chromatography conditions:
– Constant Helium flow of 1.2 mL/min.
– Oven temperature program: 40
C for 2 min, 5
C/min
ramp until 250
C, held at 250
C for 5 min.
Chromatographic time is 49 min. Total run time,
including oven cooling, is about 1 h.
6. Mass spectrometry conditions:
170
Jose ´ L. Rambla and Antonio Granell
4. A À80
C freezer for sample storage.
5. A 100–1000 μL micropipette.
6. Gas Chromatograph coupled to a mass spectrometer (see Note
6).
7. Combi-PAL autosampler adapted for SPME, including a Fiber
Conditioning Module (see Note 7).
8. A DB-5 ms GC capillary column (60 m length, 0.25 mm
internal diameter, 1.0 μm film thick).
3 Methods
3.1 Volatile
Apocarotenoid Method
3.1.1 Sampling
Procedure
1. Clean the Citrus fruit surface with deionized water and carefully dry with a paper cloth.
2. Cut the fruit transversally in two pieces and extract the juice
with a hand juicer (see Note 8).
3. Take 2 mL of the juice with a micropipette and transfer to the
bottom of a 10 mL headspace vial.
4. Close the vial tightly and freeze immediately.
5. Store at À80
C until analysis (see Note 9).
3.1.2 Sample
Preparation
1. Incubate the vial for 10 min at 20
C in a water bath to allow
the sample to thaw.
2. Locate the vial in the autosampler tray and analyze immediately
(see Note 10).
3.1.3 HS-SPME GC-MS
Analysis
1. Preincubate de vials at 50
C for 10 min with 500 rpm agitation
by means of the CombiPAL autosampler.
2. Insert the SPME holder in the vial, and expose the 50/30 μm
DVB/CAR/PDMS fiber to the headspace for volatile extraction at 50
C for 20 min with 500 rpm agitation.
3. Desorb the volatiles by introducing the fiber in the injection
port at 250
C for 1 min in splitless mode.
4. Clean the fiber in the Fiber Conditioning Module with Helium
flow at 250
C for 5 min to prevent cross-contamination.
5. Gas chromatography conditions:
– Constant Helium flow of 1.2 mL/min.
– Oven temperature program: 40
C for 2 min, 5
C/min
ramp until 250
C, held at 250
C for 5 min.
Chromatographic time is 49 min. Total run time,
including oven cooling, is about 1 h.
6. Mass spectrometry conditions:
170
Jose ´ L. Rambla and Antonio Granell