AOAC OMB Final Action Recommendation (December 2019)-2016.14
2016.14 (October 2019) – FOS-03 METHOD
FOR ERP USE ONLY DO NOT DISTRIBUTE
(d) Post-column addition reagent, sodium hydroxide solution (300 mM).— Into an eluent bottle,
197
introduce 985 mL water C(a) and add (using a single-use plastic pipette) 15.6 mL of 50 % (w/w)
198
NaOH solution C(j) . Swirl the solution gently to mix and degas for 20 min. Stable for 1 month at
199
200
room temperature, degas on day of use.
G.
Preparation of Standards
201
Using volumetric flasks, prepare a 6-level standard curve by diluting the glucose stock solution D(e) and 202 the fructose stock solution D(f) made up to the final volume with water C(a), as described in Table 203 2016.14B . 204 Treat each of the 6 standard solutions as follows: Into a 1.5-mL microtube, transfer 200 µL of standard 205 solution, 200 µL of water C(a) and 100 µL of N,N’- diacetylchitobiose internal standard solution D(d) (use 206 same N,N’-diacetylchitobiose solution for standards and samples), mix well (vortex). Then transfer 400 µL 207 of this solution to a 2-mL microtube, add 1200 µL of SPE elute solution D(n) and mix well (vortex). To 208 700 µL of this solution, add 300 µL of sodium acetate buffer D(c) . Mix well (vortex) and centrifuge at 209 10 000 × g for 5 min. Transfer 900 µL of the supernatant into a vial suitable for the instrument 210
211
autosampler.
Table 2016.14B. Dilution scheme for the preparation of the standard curve 212
Volume of fructose stock solution, µL
Volume of glucose stock solution, µL
Fructose concentration, µg/mL
Glucose concentration, µg/mL
Final volume, mL
Standard
Level 1 Level 2 Level 3 Level 4 Level 5 Level 6
200 400 800
40
100
20
2
200 400 600 800
20 20 20 20 20
200 400 600 800
50
100 150 200 250
1200 1600 2000
1000
1000
10
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