AOAC OMB Final Action Recommendation (December 2019)-2016.14

2016.14 (October 2019) – FOS-03 METHOD

FOR ERP USE ONLY DO NOT DISTRIBUTE

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- Isocratic pump for post-column delivery, with pulse dampener, 125-µL reaction coil (or

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equivalent) and T-piece.

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- Data acquisition system.

C.

Chemicals and Standards

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(a) Deionised Water. —Purified with resistivity ≥18 MΩ .

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(b) Maleic acid. —Puriss., ≥ 99.0 %.

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(c) Acetonitrile .—Gradient grade for liquid chromatography.

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(d) Acetic acid .—Glacial 100 % anhydrous, GR for analysis.

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(e) Potassium cyanohexaferrate(II)trihydrate .—[Optional].

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(f) Zinc acetate .—[Optional].

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(g) Trifluoroacetic acid (TFA) .—99 %.

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(h) Hydrochloric acid .—1 M .

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(i) Sodium acetate .—Anhydrous, ≥99.0 % (only when using PA1 column for HPAEC-PAD).

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(j) Sodium hydroxide .—50 % ( w/w ). Carbonate is a divalent anion at pH ≥ 12 and binds strongly to 69 the analytical column. It causes decrease of column selectivity and reduction of resolution and 70

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efficiency. To keep the concentrated NaOH solution carbonate free and avoid production of

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carbonate, several precautions should be taken:

- The bottle should be handled with care to keep the precipitated carbonate at the bottom (do

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not shake or stir before use).

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- The solution should never be poured from the bottle.

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- Only plastic pipettes should be used.

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- The solution should be pipetted from the center of the bottle, not from edges or bottom.

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- The unused solution should never be returned to the bottle.

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- The bottle should be closed immediately after each use.

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