6. AOACSPIFANMethods-2018Awards

30

10 H aselberger & Jacobs : J ourna of AOAC I nternati nal V l. 99, No. 6, 2016

H aselberger & J acobs : J ournal of AOAC I nternational V ol . 99, N o . 6, 2016  1585

either scFOS or oligofructose (group 1 fructan, for purposes of CF assignment). These six samples were overspiked with either scFOS or oligofructose at ~50 and 100% of the endogenous level. Two of the unfortified SPIFAN products were spiked at two levels with either inulin (HP) or an oligofructose/inulin mixture (Synergy 1). SPIFAN sample overspike and spike configurations are described in Tables 2016.06B and C . Both of these sample sets were analyzed in duplicate on each of 3 days. In addition to the SPIFAN matrixes, in-house low-lactose, milk- based infant formula containing GOS was spiked at two levels with three different fructans. Table 1 provides spike information for the latter. The six fructan-containing SPIFAN samples were analyzed in duplicate on each of 6 days. In addition to the SPIFAN products, four Abbott in-house materials were also analyzed. Three of those were analyzed in duplicate on each of 10 days, by each of two independent laboratories. A fourth in-house (control) sample was analyzed in duplicate on each of 10 days by three independent laboratories. Repeatability and intermediate precision metrics were calculated for each of the 10 samples for which replicate data was collected. Specificitywas evaluated primarily by analysis of products not fortified with fructans, in order to determine potential apparent background (Table 2). Each of these products was analyzed in duplicate. In addition, chromatograms of multiple maltodextrin commodities and products containing either hydrolysate protein or free amino acids were examined for potential interferences Precision Specificity

Table 2. SPIFAN kit products without added fructan - (analyzed for specificity evaluation)

Total fructan found a

Sample type, batch

ND b

Infant elemental powder

Adult nutritional RTF high protein Adult nutritional RTF high fat Infant formula RTF milk based

ND ND ND ND ND ND ND ND ND ND

SRM 1849a

Infant formula powder partially hydrolyzed milk based

Infant elemental powder

Infant formula powder milk based Infant formula powder soy based Infant formula RTF milk based Adult nutritional RTF high protein

a Mean fructan level detected in Part II of method analysis. b   ND = Not detected; No fructose peak could be identified. Detection limit  was not experimentally determined but it is estimated that apparent fructan in these samples is consistently <0.01%.

the validation work, spanning a period of 10 months. Relative calibration errors for each standard were calculated and used as the basis for determining adequacy of fit to the quadratic calibration model.

Accuracy

Because there are no relevant certified reference materials, assessment of accuracy was based entirely on recovery of fructans from spiked samples. The samples used for these experiments were products included in the Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) Sample Kit. Of these, six were determined to contain fructan in the form of

4.00%

3.00%

2.00%

1.00%

0.00%

-1.00%

-2.00%

Relative Calibration Error

-3.00%

-4.00%

1

2

3

4

Standard Level

Figure 2. Relative calibration errors (composite from 43 analytical runs).