AOAC RI ERP E-Book - DS DF

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

where PA-Glu = peak area of D-glucose; PA-IS = peak area of internal standard (glycerol); Wt-Glu = mass of D-glucose in standard; and Wt-IS = mass of internal standard (glycerol) in standard. (e) Calibrate the area of the chromatogram to be measured for SDFS. Use a 100- μL LC syringe [ , B(dd )] ) to fill the 50-μL injection loop with retention time standard [ , C(h )] ) . Inject in duplicate. Determine the demarcation point between DP2 and DP3 oligosaccharides (disaccharide maltose versus higher oligosaccharides) (Figure 2017.xxD). (f) Determine peak areas of SDFS (PA-SDFS) and internal standard (PA-IS) in chromatograms of sample extracts. Inject sample extracts [ , H(c )] ) on LC. Record areas 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.

I. Calculations for HMWDF ( IDF + SDFPby gravimetry ) Blank (B, mg) determination .

B = [(BR 1 + BR 2 )]/2 – P B – P A

Where: BR 1 and BR 2 = residue mass, in milligrams, for duplicate blank determinations, respectively, and P B and P A = mass, in milligrams, of protein and ash, respectively, determined on first and second blank residues. where : R 1 = residue mass 1 from M 1 in milligrams; R 2 = residue mass 2 from M 2 in milligrams; M 1 = test portion mass 1 in grams; M 2 = test portion mass 2 in grams; P A = ash mass in milligrams from R 1 ; P B = protein mass in milligrams from R 2 . AOAC Research Institute ERP Use Only HMWDF = (mg/100 g) = [(R 1 + R 2 )/2 – P B – P A – B]/(M 1 + M 2 )/2] x 100 WhereHMWDF (% w/w) = HMWDF (mg/100g)/1,000

Method updated 2008--08-10 This copy printed 22 August 2017

18