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Memo
Monique Steegmans
16001n-MSS-MSS-SLV FOS01 AOAC997.08 Beneo-Orafti, 1 Febr 2016, page 5/18
The compounds are: fructose, glucose, sucrose, others can be added if needed.
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 cm 3 with H 2 O bid .
For standard and sample solutions:
-
Defatting procedure
Samples containing considerable amounts of fat like these infant formula samples
should be defatted. Therefore, take 4 cm 3 of the sample and IS solution and add 4
cm 3 hexane. Mix on vortex during 10 minutes and centrifuge. Discard the upper layer
with a Pasteur pipette. Repeat the whole extraction procedure with the remaining
layer.
-
Transfer 200 µl of the aqueous solution in a glass test tube.
- Drying procedure:
- add about 0,5 cm 3 dichloromethane, mix and dry under N 2 until constant volume.
Repeat the previous procedure until the sample is dry.
2.2.4 Derivatization
- Add 400 µl hydroxylamine-HCl solution, prepared by dissolving 0,67 g NH 2 OH
.
HCl in 25
cm 3 dry pyridine.
This solution can be stored in the refrigerator for 1 month.
- Mix 10 min. on vortex.
- Warm up and shake (± 200 RPM) in a heating block at 60 °C during 15 minutes, after 5
min. shake a few seconds on vortex and continue heating.
- Centrifuge the tubes during 5 min. (± 2200 tr.) and dry under N
2
.
- Add 200 µl N-(Trimethylsylil)imidazole (TMSI) and mix on vortex during 10 min.
- Add 1 cm 3 H 2 O bid. to hydrolyse the excess of TMSI, shake manually.
- Add 2 cm 3 iso-octane and mix on vortex during 3 min, then centrifuge 5 min. (± 2200
RPM).
- 1 µl of the iso-octane phase is injected.
Fos-01 (February 2016)
FOR ERP USE ONLY
DO NOT DISTRIBUTE