AOAC OMB Final Action Recommendation (December 2019)-2016.14

2016.14 (October 2019) – FOS-03 MANUSCRIPT

FOR ERP USE ONLY DO NOT DISTRIBUTE

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Optional: Add 0.5 % sodium azide solution D(i) to a final concentration of 0.0125 % to

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mobile phase B. This extends shelf life of eluent to about 2 weeks and can improve

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chromatographic resolution around N’,N-diacetylchitobiose in case of problems.

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(c) Mobile phase C for CarboPac PA1, sodium acetate solution (1 M).— Into a 1000-mL

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volumetric flask, weigh 82.0 g anhydrous sodium acetate and dissolve with 800 mL water

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C(a) by mixing. Make up to the mark with water C(a) and filter on a 0.20 µm nylon

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membrane filter into an eluent bottle. Degas with helium for 20 min and protect the eluent

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from exposure to carbon dioxide until, and during use by suitable means (e.g. by keeping

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under a blanket of helium). Stable for 1 week at room temperature.

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(d) Post-column addition reagent, sodium hydroxide solution (300 mM).— Into an eluent

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bottle, introduce 985 mL water C(a) and add (using a single-use plastic pipette) 15.6 mL

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of 50 % (w/w) NaOH solution C(j) . Swirl the solution gently to mix and degas for 20 min.

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Stable for 1 month at room temperature, degas on day of use.

G. 14 Using volumetric flasks, prepare a 6-level standard curve by diluting the glucose stock solution 15 D(e) and the fructose stock solution D(f) made up to the final volume with water C(a), as described 16 in Table 2016.14B . 17 Treat each of the 6 standard solutions as follows: Into a 1.5-mL microtube, transfer 200 µL of 18 standard solution, 200 µL of water C(a) and 100 µL of N,N’- diacetylchitobiose internal standard 19 solution D(d) (use same N,N’-diacetylchitobiose solution for standards and samples), mix well 20 (vortex). Then transfer 400 µL of this solution to a 2-mL microtube, add 1200 µL of SPE elute 21 solution D(n) and mix well (vortex). To 700 µL of this solution, add 300 µL of sodium acetate 22 buffer D(c) . Mix well (vortex) and centrifuge at 10 000 × g for 5 min. Transfer 900 µL of the 23 supernatant into a vial suitable for the instrument autosampler. 24 Preparation of Standards

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