ISO 22184:2021 Milk and milk products — Determination of the sugar contents — High performance anion exchange chromatography with pulsed amperometric detection method (HPAEC-PAD)

ISO 22184:2021 Milk and milk products — Determination of the sugar contents — High performance anion exchange chromatography with pulsed amperometric detection method (HPAEC-PAD). 5 Reagents Use only reagents of recognized analytical grade and water in accordance with ISO 3696, unless otherwise specified. 5.1 Water, conforming to ISO 3696, grade 3 and grade 1. 5.2 Sodium hydroxide (NaOH) pellets. 5.3 Aqueous sodium hydroxide solution, substance concentration c = I rnol/l. Add to a 1 000 ml volumetric flask 40 g ± 1 g NaOH pellets (L2), dissolve in about 500 ml of water and, after cooling down, dilute with water to the mark and homogenize. 5.4 Sodium hydroxide solution, mass fraction w(NaOH) = 33 % in water. 5.5 Sodium hydroxide solution, mass fraction w(NaOH) = 50 % in water. The amount of carbonate and mercury in the reagent should be minimized. Do not shake or stir the solution before use. A suitable commercially available carbonate sodium hydroxide solution may also be used. 5.6 Concentrated hydrochloric acid (HCI), mass fraction of 36 % to 38 % in water. 5.7 Aqueous hydrochloric acid solution, c = 1 mol/l. Add to a 1 000 ml volumetric flask (fZ) 500 ml of water followed by 83 ml of concentrated HCI (Ifi) and, after cooling down, dilute with water to the mark and homogenize. 5.8 Acetonitrile (I-IPLC quality). 5.9 Acetonitrile in water, a volume fraction of 5 % in water. Add to a 1 000 ml volumetric flask (62) 50 ml of acetonitrile (15), dilute with water grade 3 to the mark and homogenize. 5.10 Anhydrous sodium acetate (CH3COONa) (HPLC quality). 5.11 Eluent 1 (El), aqueous solution of sodium acetate (CH3COONa), c = 1,0 mol/l. Add to a 1 000 ml volumetric flask fl2) about 800 ml of degassed water grade I (eluent 3,113) followed by 82,0 g sodium acetate (LLO). Then dilute the aqueous solution with degassed water (eluent 3, J3) to the mark and homogenize. Store the eluent under an inert atmosphere. 5.12 Eluent 2 (E2), aqueous solution of carbonate free sodium hydroxide (NaOH), c = 0,2 mol/l. Add to a 1 000 ml volumetric flask (62) about 800 ml of degassed water grade 1 (eluent 3, 5J.3) and purge for 15 mm with helium. Add 16,0 g of sodium hydroxide solution (15). Then quickly dilute the aqueous solution with degassed water grade 1 (eluent 3, S.13) to the mark, immediately close the...