AOAC RI ERP E-Book - DS DF

K-RINTDF.2016_11_K-RSTAR.DATA.NEW 27/09/2016 11:54 Page 17

OMAMAN-38 C: Instructions for Use Expert Review Panel Use Only September, 2017

solution to dryness on a rotary evaporator and re-dissolve the residue in 32 mL of deionised water. To 5 mL of this solution in a polypropylene tube [B(s)] , add 1.5 g of Amberlite ® FPA53 (OH − ) resin and 1.5 g of Ambersep ® 200 (H + ) and swirl the contents regularly over 5 min. Allow the resin to settle and remove the supernatant (1.5-2.0 mL) with a syringe [B(cc)] and filter through a polyvinylidene fluoride filter, pore size 0.45 μ m [B(z)] . Inject an aliquot (50 μ L) of this solution onto the TSK columns (with deashing pre-column in place). A pattern similar to that shown in Figure 12c should be obtained i.e. no salt peaks should be evident. (a) Filtrate recovery and concentration .— {Set aside the filtrate from one of the sample duplicates [G (c)] to use if duplicate SDFS data is desired}. Transfer one quarter of the filtrate [G (c)] of the other sample duplicate, i.e. 75 mL from [G (c)] to a

500 mL evaporator flask and evaporate to dryness under vacuum at 60°C. Redissolve in 8 mL of deionised water.

(b) Deionisation of sample .— Transfer the 5 mL of sample concentrate [I(a)] to a 13 mL polypropylene tube [B(s)] (quantitative transfer is not required as the sample contains glycerol internal standard). Add ~ 1.5 g of Amberlite ® FPA53 (OH - ) resin [C (p)] and ~ 1.5 g of Ambersep ® 200 (H + ) [C (q)] resin to the tube and invert the tube contents over 3-4 min (Figure 11, page 21). a 0.45 mm filter [B(z)] . Alternatively, transfer 1 mL of the solution to a microfuge [B(ff)] centrifuge tube and centrifuge at 13,000 rpm for 3 min. Use a 100 μ L LC glass syringe [B(dd)] to fill the 50 μ L injection loop on the LC [B(t)] . A single analysis of the sample is adequate. Column: TOSOH TSK gel permeation column [B(w)] with de-salting pre-column [B(v)] . Solvent: microfiltered [B(bb)] , distilled water. Flow rate: 0.5 mL/min; 60 min per run. Temperature: 80°C. (d) Determine the response factor for D-glucose . — Since D- glucose provides an LC refractive index (RI) response equivalent to the response factor for the non-digestible oligosaccharides that make up SDFS the LC is calibrated using D-glucose, and the response factor is used for determining the mass of SDFS. Use AOAC Research Institute ERP Use Only (c) Preparation of samples for LC analyses .— Transfer the solution to a 10 mL disposable syringe [B(cc)] and filter through

a 100 m L LC syringe to fill a 50 m L injection loop with the standard glycerol/D-glucose solution ( Bottle 5 ). Inject in

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