6. AOACSPIFANMethods-2018Awards

29

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

)58&7$1 >PRGLILHGE\+$6(/3$@

&/& B5

('B

Q&

*OXFRKHSWRVH

)UXFWRVH

PLQ

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.