AOAC OMB Final Action Recommendation (December 2019)-2016.14

2016.14 (October 2019) – FOS-03 METHOD

FOR ERP USE ONLY DO NOT DISTRIBUTE

NaOH solution C(j) . Swirl the solution gently to mix and degas for 20 min. Stable for 1 month at

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room temperature, degas on day of use.

F.

Mobile Phase Preparation (Using CarboPac PA1 column or Equivalent)

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If using a CarboPac PA20 column (or equivalent), skip this section.

(a) Mobile phase A for CarboPac PA1, sodium hydroxide solution (200 mM).— Weigh 1923 ± 2 g water

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C(a) into an eluent bottle and degas with helium for 20 min. Add 20 mL of 50 % (w/w) NaOH

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solution C(j) . Degas with helium for 20 min and protect the eluent from exposure to carbon

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dioxide until, and during use by suitable means (e.g. by keeping under a blanket of helium). Stable

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for 1 week at room temperature.

(b) Mobile phase B for CarboPac PA1, deionised water resistivity ≥18 MΩ.— Fill a 2-L eluent bottle

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with 2000 mL water C(a) . Degas with helium for 20 min and protect the eluent from exposure to

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carbon dioxide until, and during use by suitable means (e.g. by keeping under a blanket of helium).

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Stable for 4 days at room temperature.

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

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

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

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

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flask, weigh 82.0 g anhydrous sodium acetate and dissolve with 800 mL water C(a) by mixing.

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Make up to the mark with water C(a) and filter on a 0.20 µm nylon membrane filter into an eluent

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bottle. Degas with helium for 20 min and protect the eluent from exposure to carbon dioxide until,

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and during use by suitable means (e.g. by keeping under a blanket of helium). Stable for 1 week

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at room temperature.

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