AOAC OMB Final Action Recommendation (December 2019)-2016.14

2016.14 (October 2019) – FOS-03 MANUSCRIPT

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difference when using Carrez clarification was that the extract was clear (compared to without 1 clarification which gives a turbid extract), otherwise there was no impact on the result or on the 2 ease of performing the analysis. 3 In addition to the participant’s comments, the ERP also proposed some modifications. Following 4 the reviewer’s remarks, a recommendation on how to check performance of the fructanase was 5 added, as well as enzyme activity requirements for both sucrase and fructanase. Storage conditions 6 and durations of reagents have also been included in the final method, as well as the centrifugation 7 time for the working standard solutions that was missing. A member of the panel was concerned 8 about the use of sodium azide in this method. In fact a number of MLT participants running the 9 PA1 chromatography omitted the azide from mobile phase B and achieved good results. 10 Nevertheless tests in one of the author’s laboratories indicated that when the azide is omitted it can 11 negatively impact the chromatographic resolution. It has thus been changed to an optional reagent, 12 which can be avoided if not needed. System suitability tests are included now in the method, as 13 well as examples of calibration curves. 18 evaluation with the analysis of a practice sample. A child formula powder was selected for this 19 purpose, and participants used the sample to set up the method and become familiar with the 20 protocol. Several labs encountered chromatographic problems and some technical support was 21 given. One participant contacted us because they were experiencing sudden lower fructan results 22 for in-house reference materials with a particular batch of the enzyme mixture sucrase, α-amylase, 23 pullulanase and maltase. Further investigations were conducted in the laboratory of the Study 24 Director and at the enzyme supplier. As a result, it was concluded that this particular batch of 25 enzyme was not performing as expected with this assay and should not be used for this MLT. All 26 14 15 Results and Discussion 16 Practice Sample 17 The 14 participating laboratories, randomly coded for identification, started the method

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