AOAC RI ERP E-Book - DS DF

K-RINTDF.2016_11_K-RSTAR.DATA.NEW 27/09/2016 11:54 Page 18

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

duplicate. Obtain the values for the peak areas of D-glucose and internal standard (glycerol) from duplicate chromatograms. The ratio of peak area of D-glucose/peak area of internal standard (glycerol) to the ratio of the mass of D-glucose/mass of internal standard (glycerol) is the “response factor.” The average response factor for D-glucose vs glycerol is ~ 0.82.

Response factor (Rf) = (PA-IS) /(PA-Glc) x (Wt-Glc / Wt-IS)

where: PA-IS PA-Glu Wt-Glu

= peak area internal standard (glycerol; Gly).

= peak area D-glucose (Glc).

= mass of D-glucose in 1 mL of Glc/Gly standard. = mass of glycerol in 1 mL of Glc/Gly standard.

Wt-IS

(e) Calibrate the area of chromatogram to be measured for LMWSDF . — Use a 100 μ L LC syringe [B(dd)] , to fill the 50 μ L injection loop with retention time standard [C (m)] . Inject in duplicate. Determine demarcation point between DP 2 and DP 3 oligosaccharides (disaccharides maltose versus higher oligosaccharides) (see Figure 6 for separation of sucrose from F3 and kestose, page 20). (f) Determine peak area of SDFS (PA-SDFS) and internal standard (PA-IS) in chromatograms of sample extracts . — Inject sample extracts [I(c)] on LC. Record area of all peaks of DP greater than the DP2/DP3 demarcation point as PA-SDFS. Record the peak area of internal standard as PA-IS.

J. CALCULATIONS for HMWDF, IDF and SDFP:

Blank (B) determination (mg): AOAC Research Institute ERP Use Only = BR 1 + BR 2 - P B - P A 2

where:

BR 1 and BR 2 = residue mass (mg) for duplicate blank determinations respectively. P B and P A = mass (mg) of protein and ash respectively, determined on first and second blank residues.

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