AOAC OMB Final Action Recommendation (December 2019)-2016.14

2016.14 (Jan. 2019) FOS-03 MLT Report FOR ERP USE ONLY DO NOT DISTRIBUTE

exposure to carbon dioxide until, and during use by suitable means (e.g. by keeping under a blanket of helium). (b) Mobile phase B for CarboPac PA20, deionised water resistivity ≥18 MΩ.— Into a HPLC bottle, introduce 2000 mL of water C(a) and degas with helium for 20 min. Thereafter protect the eluent from exposure to carbon dioxide until, and during use by suitable means (e.g. by keeping under a blanket of helium). (c) Mobile phase C for CarboPac PA20, sodium hydroxide solution (30 mM).— Into a HPLC bottle, introduce 1000 mL of water C(a) and degas with helium for 20 min. Add (using a single-use plastic pipette) 1.6 mL of 50 % (w/w) sodium hydroxide solution C(j) . Degas with helium for 20 min and protect the eluent from exposure to carbon dioxide until, and during use by suitable means (e.g. by keeping under a blanket of helium). (d) Post-column addition reagent, sodium hydroxide solution (300 mM).— Into a HPLC bottle, introduce 985 mL of water C(a) and add (using a single-use plastic pipette) 15.6 mL of 50 % (w/w) sodium hydroxide solution. Swirl the solution gently to mix and degas for 20 min. F. Mobile Phase Preparation (Using CarboPac PA1 column or Equivalent) 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 C(a) in the eluent bottle and degas with helium for 20 min. Add 20 mL of 50 % (w/w) sodium hydroxide solution C(j) . Degas with helium for 20 min and protect the eluent from exposure to carbon dioxide until, and during use by suitable means (e.g. by keeping under a blanket of helium). (b) Mobile phase B for CarboPac PA1, deionised water resistivity ≥18 MΩ with sodium azide.— Fill a 2-L eluent bottle with 1950 mL water C(a) . Add 50 mL of 0.5 % sodium azide solution D(i) . Degas with helium for 20 min and protect the eluent from exposure to carbon dioxide until, and during use by suitable means (e.g. by keeping under a blanket of helium). (c) Mobile phase C for CarboPac PA1, sodium acetate solution (1 M).— Into a 1000-mL volumetric flask, weigh 82.0 g anhydrous sodium acetate and dissolve with 800 mL water C(a) by mixing. Make up to the mark with deionised water and filter on a 0.20 µm nylon membrane filter into an eluent bottle. Degas with helium for 20 min and protect the eluent from exposure to carbon dioxide until, and during use by suitable means (e.g. by keeping under a blanket of helium). (d) Post-column addition reagent, sodium hydroxide solution (300 mM).— Into a HPLC bottle, introduce 985 mL water C(a) and add (using a single-use plastic pipette) 15.6 mL of 50 % (w/w) sodium hydroxide solution. Swirl the solution gently to mix and degas for 20 min.