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Annex 4 Description of the GC method.
1.
Principle:
This method is applied to analyze glucose, fructose and sucrose accurately.
An internal standard (IS) is added to the sample followed by drying under vacuum.
After treatment of the dried sample with hydroxylamine, the sugars are derivatised with
trimethylsilylimidazole (TMSI).
After the addition of water the volatile derivates are extracted with isooctane and the isooctane
phase is injected on a capillary column.
2.
Apparatus:
- Gas Chromatograph: Thermo Trace GC with autosampler or similar.
- Column: OV1 60 m, 0,32 mm ID and film thickness 0,1 µ, or similar.
- On-column injector.
- FID-detector: 350°C.
Air: 350 ml/min
H
2
: 35 ml/min
Make-up (N2): 30 ml/min
- Temperature program of the oven: 95/0/40/172/15/10/272/15/10/340/4,9 or equivalent
- Carriergas: H
2
, constant pressure: 167 kPa
- Injection volume 1 µl
- Time of analyses: 53,5 min
All mentioned parameters can be adapted to optimise the chromatography.
3.
Procedure:
- With each set of samples, 4 standards are analyzed in order to check the response factors.
The standard solutions are prepared according to next composition:
mg compound
mg I.S.
total vol. with H 2 O bid.
Std. 1
20
80
200 cm 3
Std. 2
20
40
100 cm 3
Std. 3
20
20
50 cm 3
Std. 4
30
20
50 cm 3
The compounds are: fructose, glucose, sucrose.
These compounds are predried under vacuum at least 48 hours in the presence of silicagel.
The IS (internal standard) is rhamnose.
- A quantity of sample is weighed accurately together with 20 mg of IS.
Dissolve and dilute to 50 m
3
with H 2 O bid .
FOS-01 w/SLV
FOR ERP USE ONLY
DO NOT DISTRIBUTE