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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

CONFIDENTIAL

· This document may not be reproduced or disclosed to third parties without prior authorization

Page 5 / 9

MLT code

Bottle #

Conc (mg/100g)

XKIP216

1

12.7

12.6

2

10.6

10.5

HYJU890

1

14.9

15.1

2

11.6

11.6

While the duplicates from the same bottle present excellent CV (from 0.1 % to 0.9%). The range of

concentration spans from 10.5 to 15.1 mg/100 g. It can indicate that the high precision data

obtained for the Infant Formula RTF is due to the variability within the samples and not on the

method.

To confirm these findings, it was decided to analyse samples at NRC, in duplicates, using a different

method (AOAC Official method 985.33). This method is based on a different chemical approach: the

reduction of the dye 2,6-dichlorophenolindophenol (DCPIP) by ascorbic acid. The results obtained

can be found in the table below:

MLT code

Bottle #

Conc (mg/100g)

XKIP216

1

14.5

XKIP216

1

14.9

XKIP216

2

11.4

XKIP216

2

11.7

HYJU890

1

14.9

HYJU890

1

14.8

HYJU890

2

13.7

HYJU890

2

13.7

For these samples the range of concentrations spans from 11.4 to 14.9 mg/100 gr.

Both tables tend to indicate that the high precision data collected during this additional MLT could

come from the variability of the samples, and not from the method AOAC 2012.22. Moreover this

variability has been observed using two distinct analytical methodologies.

AOAC OMB Meeting Book

379