AOAC OMB Final Action Recommendation (December 2019)-2016.14

2016.14 (October 2019) – FOS-03 METHOD

FOR ERP USE ONLY DO NOT DISTRIBUTE

0.2 – 4.0 2.5 – 45 25 – 100

0.03 – 0.45

No dilution

No dilution

1

0.3 – 4.5 3.0 – 45

5

50 50

10

0.5

100

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(e) Hydrolysis of sucrose and α-glucans.— Transfer 200 µL Solution B H(d) into a 1.5-mL microtube,

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add 100 µL of N,N’ -diacetylchitobiose internal standard solution D(d) and 200 µL sucrase/ β -

236

amylase/pullulanase/maltase enzyme mixture D(j) . Mix well (vortex), place the microtubes on a

237

floating rack and incubate at 40 °C for 90 min. Cool down to room temperature. NOTE: Adapt

238

these conditions (time and temperature) according to enzyme manufacturer recommendations.

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(f) Optional Carrez Clarification .—(Use in case of difficulties passing sample through SPE.) Add

240

10 µL Carrez I solution D(g) to the sample and mix well. Then add 10 µL Carrez II solution D(h)

241

and mix again. Centrifuge at 10 000 x g for 10 min and use the supernatant for the next step H(g) .

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(g) Removal of monosaccharides.— Prepare the graphitized carbon SPE columns B(l) , as follows (try

243

to avoid passing air through the SPE column before the final elution step (g) as this may result in

244

higher blank measurements):

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a. Flush with 3 × 400 µL SPE wash solution D(l) .

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b. Flush with 3 × 400 µL water.

247

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Then perform the following steps under gravity if possible, or up to an elution flow rate

249

of 2 mL/min with positive pressure:

c. Apply 400 µL of the enzyme treated solution H(e) or H(f) .

250

d. Wash with 2 × 1 mL NaCl solution D(m) .

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e. Wash with 4 × 1 mL water.

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f. Elute the fructans into a 2-mL microtube using 4 × 400 µL SPE elute solution D(m) .

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g. Apply a little positive pressure to eliminate all solution from the column.

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h. Mix eluates from the SPE column well (vortex).

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