2012.20 Choline MLT

Summary of the Choline MLT- August 2016

Jeff Rohrer, Ph. D.

This MLT of

AOAC 2012-20 Determination of Choline in Infant Formula and Adult Nutritionals by

Ion Chromatography with Suppressed Conductivity Detection

was started in October 2014 with

Brian De Borba as the study director. Brian changed jobs in the March 2015 and at that time I

assumed the role of study director. The study was short on labs and some of the labs that

originally committed to the study backed out. I tried to recruit labs on at least two occasions

and was able to secure five more labs to arrive at the final total of eleven. I loaned equipment

to two labs. While trouble-shooting an issue with one of those labs two protocol errors were

discovered. One was inconsequential (preparation of standard solution that is not used in the

study), but the other instructed the analyst to prepare the lowest calibration standard at a

concentration that was 10-fold less than desired. Only the last three participating labs received

the correct protocol and one still followed the original protocol. I had that lab recalculate their

results without the low calibration point and it had little impact on their results. A few of the

first eight labs modified the calibration range to eliminate the point in error.

I have submitted six blind duplicate Excel sheets with the data for all labs (3 Ready-to-Feed

(RTF) and 3 powdered samples). I have also submitted sheets for the two of powdered samples

where data from some labs have been removed to satisfy the statistical tests. Finally there is a

Table summarizing the data from the six samples (some data removed from two of the

powdered samples as described above). The same table is in Appendix 1 of this document.

Table 1 lists the files submitted.

Table 1 – Documents Submitted (not including this one)

File

Description

Choline 2012-20 MLT LUJP087 & ADVZ021.xls

Blind Duplicates of Powdered Samples -

LUJP087 & ADVZ021

Choline 2012-20 MLT LARU224 & GLVC238.xls Blind Duplicates of Powdered Samples -

LARU224 & GLVC238

Choline 2012-20 MLT LARU224 & GLVC238 –

Remove Lab 10.xls

Blind Duplicates of Powdered Samples –

LARU224 & GLVC238 with Lab 10 data

removed

2012.20 CHOLINE MLT

SUMMARY OF MLT

FOR ERP USE ONLY

DO NOT DISTRIBUTE