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Additional data on Multi-Laboratory Validation – Vitamin C method AOAC First Action 2012.22 / F. Martin, NRC/AS

23.Nov.2015

R E S U L T S A N D C O N C L U S I O N

Participation to MLT From the 12 laboratories that initially initially accepted to participate, two of them did not receive the MLT samples due to customs restrictions. The remaining 10 laboratories reported valid data. Results Summarized results of the additional MLT set of samples can be found in the table below. Full set of data is given in Annex B .

Requirements (SMPR 2012.012)

≤ 5 % ≤ 10 %

Sample

n

Mean (mg/100 g RTF)

RSD r (%)

RSD R (%)

HorRat

10 10

17.6 12.0

1.5

6.5

0.88 1.70

Adult Nutritional Powder Low Fat Infant Formula RTF Milk Based

10.7

13.2

n = number of laboratories (after outliers removal) RSD r : relative standard deviation of repeatability RSD R : relative standard deviation of reproducibility

The results for the Adult Nutritional Powder Low Fat product are now well within the SMPR requirements. The repeatability went down from 31.8 % for the first round to 1.5 % in the present study, whereas the reproducibility went down from 33.0 % to 6.5 %. The hypothesis that during the first round the high precision data came from either homogeneity of the sample itself, storage spoilage or can mislabelling seems to be confirmed. Regarding the Infant Formula RTF Milk Based, even if the precision numbers improved (repeatability down from 25.6 % to 10.7 %, reproducibility from 30.6 % to 13.2 %), they remained slightly outside of the requirements. One of the participant laboratories analysed duplicate samples the four bottles they received. The data are presented in the table below:

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