AOAC OMB Final Action Recommendation (December 2019)-2016.14

2016.14 (Jan. 2019) FOS-03 MLT Report FOR ERP USE ONLY DO NOT DISTRIBUTE

MLT Samples The analytical results submitted by the 12 participants on the MLT samples were analysed and the results of the statistical evaluation are shown in Table 4 . The full set of data per laboratory and per sample is depicted in Tables 5 and 6 . The main purpose of the study was to collect precision data, however results on SRM 1869 (0.204 g/100 g) can be compared with the available reference value (not certified) (0.212 ± 0.085 g/100 g) and shows good agreement, demonstrating satisfactory accuracy of the method. The mean fructan concentrations in the infant formula and adult nutritionals analysed in this study were in the range 0.0308 to 2.67 g/100 g of reconstituted final products, which corresponds to the lowest level required in the SMPR 2014.002 and to the highest level commercially available sample, respectively. Repeatability and reproducibility were not always well within the limits stated in the SMPR 2014.002. Values of RSD r ranged from 2.3 to 7.7 % and RSD R were between 5.9 and 15.1 %. Only one product had both repeatability and reproducibility values slightly higher than the requirement (7.7 % and 12.8 % respectively) and 2 other samples showed reproducibility values higher than SMPR (15.1 % and 14.6 %). Two out of these 3 products were liquid samples, which presented a deposit on the bottom of the container. It could be that if the samples were not well agitated these samples could present an inhomogeneity. However considering the numerous deviations applied to the MLT protocol by the participants and the wide range of chromatographic conditions used, these precision data demonstrate a rather robust method. For most of the samples, all 12 participants’ results were included for statistical analysis. Only 3 outliers were removed prior to statistical analysis based on Cochran’s and Grubbs’ tests. Lab 2 was an outlier according to single Grubb’s test for SRM 1869 as well as for infant formula powder FOS/GOS, and Lab 8 was an outlier according to Cochran’s test for infant formula powder FOS/GOS sample. Without removing these outliers, the RSD r and RSD R would have been 4.4 % and 10.2 % respectively for SRM 1869, and 8.2 % and 20.8 % respectively for infant formula powder FOS/GOS. Horwitz ratio (HorRat) values were also estimated and ranged from 1.2 to 3.3. However, even if applicable to most chemical methods, HorRat is not necessary applicable to methods with indefinite analytes like polymers [12] such as fructans.