AOACSPIFANMethods-2017Awards

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1584  H aselberger & J acobs : J ournal of AOAC I nternational V ol . 99, N o . 6, 2016

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Figure 2016.06E. Control powder, milk based, chromatogram (Part II).

glucoheptose for each level of working standard. Fit the peak area ratios (responses) and corresponding standard concentrations, in µg/mL, to a quadratic model. Do not force intercept to zero. Identify glucoheptose as the internal standard. (d) Sample weight factors (SWF).— Calculated as follows: ( 1 ) R TF products and commodities. SWF = SW1 (g) × SW2 (g) × 10000 (2) Powder products. where SW 1 = weight of material delivered to a volumetric flask (RTF, or reconstituted powder) and diluted as per sample table guidelines. For example, an RTF product of 0.21–1.0% fructan would have an SW 1 of 7 g (±10%) into a 200 mL volumetric flask. SW 2 = weight of solution from volumetric flask per sample table guidelines (volumetric dilution of SW 1 ). Value should be 0.2 g ± 10%. PW = weight of powder product weighed to be reconstituted (5 g ± 10%). WW = weight of water used to reconstitute powder products (40 g ± 10%). (e)  Dilution factor (DF).— Calculated as follows: (1) Low-level fructan (RTF 0.03–0.2%, powder 0.27–1.0%). DF = 50 g × 2 mL (2) Mid-level fructan (RTF 0.21–1.0%, powder 1.1–10%). DF = 200 g × 2 mL (3) High-level fructan (RTF 1.1–5.0%, powder 11–45%). 1 SW g SW g 2 × 10 000 ( ) PW g PW g WW g ( ) ( ) + ( ) ( ) = × × SWF

DF = 500 g × 2 mL

(4) Commodity DF (46–100%).

DF = 1000 g × 2 mL (f)  Commodity factors (CF).— As determined, based on analysis in Part I. The factors chosen for the three groups listed in section G , in Part I, were done in such a way so as to cover the spectrum of fructan commodities currently in use. Any factor should then impart a bias of no more than ~5% for the grouping that it covers. If the average DP of the fructan is known, this factor can be explicitly calculated according to: CF DP DP DP Avg Avg Avg ( 1 ) *(0.9 0.1 ) = − + (g) Sample total fructan (g/100 g).— Interpolate the concentration of fructose in the injected sample (µg/mL) using the corresponding fructose response parameters. Calculate the total fructan concentration using the proper weights and factors:   = where DF = dilution factor; CF = commodity factor; SWF = sample weight factor. Total Fructan g g 100 Interpolated Fructose x DF x CF SWF  

Validation Protocol

Linearity A total of 43 standard curves (two bracketed sets of standards for each curve) were collected during the course of

Table 1. Recovery from spiked in-house GOS containing placebo

Nominal 0.3% spike

Nominal 3% Spike

No. of replicates a

Spiking material b

Sample type

Avg. % rec.

RSD, % Avg. % rec.

RSD, %

Infant formula powder, low lactose milk based with GOS Infant formula powder, low lactose milk based with GOS Infant formula powder, low lactose milk based with GOS

9 9 9

scFOS

100 99.0

5.43 6.09 2.85

96.2 96.0 97.2

2.85 2.35 2.04

Oligofructose

Oligofructose/inulin 98.4

a  Triplicates on each of 3 days. b  In-house material. scFOS = Ingredion Nutraflora FOS powder; oligofructose = Beneo Orafti P95 powder; oligofructose/inulin = Beneo Orafti Synergy 1.