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Memo
Monique Steegmans
16001n-MSS-MSS-SLV FOS01 AOAC997.08 Beneo-Orafti, 1 Febr 2016, page 4/18
The fructans are extracted from the sample with boiling water. An aliquot of the extract is
hydrolyzed with inulinase. The concentrations of glucose, fructose and sucrose are
chromatographically determined by gaschromatography: an internal standard is added to the
sample followed by drying under vacuum. After treatment of the dried sample with hydroxylamine,
the sugars are transformed to derivatives with N-(Trimethylsilyl)imidazole (TMSI). After addition of
water the volatile derivatives are extracted with iso-octane and this phase is injected on a capillary
column.
2.2.1. Apparatus
Gaschromatograph: Thermo Trace GC with autosampler
Column: AT1 60m, 0.32mmID and film thickness 0.1 μ
On column injector
FID detector: 350°C (air 350ml/min, H
2
35ml/min and make-up (N
2
) 30ml/min)
Carrier gas: H
2
constant pressure 77KPa
Temperature oven:
85°C/40°C/min/172°C/15min/10°C/min/272°C/15min/10°C/min/340°C/4min
Injection volume: 1μl
Run time: 53.2min
Analytical balance: scale interval to 0.01 mg
pH-meter
Water bath
Shaker
Vortex
Automatic pipet
Reactor/heating block at 60°C
2.2.2 Reagents
Pyridine
–
Analytical grade Regis Technologies (ref 1-270013-20)
Hydroxylamine-HCl
–
Analytical grade Carlo Erba (ref 455474) dissolve 1.25g in 50mL
pyridine. This solution is stable for one month stored in the fridge.
N-(Trimethylsilyl)imidazole (TMSI)
–
Analytical grade (ref18039)) stored under nitrogen in
the fridge
glucose, fructose, sucrose dried under vacuum.
L-rhamnose monohydrate used as IS from Sigma
–
Fluka (ref 83650)
Iso-octane VWR (ref 28781.325)
Dichloromethane VWR (ref 83623.290)
Hexane
–
Analytical grade Carlo Erba (ref 412602000)
2.2.3 Procedure
With each set of samples, 4 standards are analysed in order to check the
response factors. The standard solutions are prepared according to following
scheme:
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
Fos-01 (February 2016)
FOR ERP USE ONLY
DO NOT DISTRIBUTE