MCPD-02 Reviewer Forms (July 19, 2018)

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Reviewer 7

containing all steps for a given matrix type. Protocol was revised to include more step by step instructions which was VERY helpful.

Points for clarification:

Page 69: Liquid test sample-need better explanation

Pg72- Solution 4- “acid solution has to be adjusted by diluting or by adding more o-phosphoric acid to solution 2 ” –Should it be solution 4? Clarification of the calculations for the concentrations of the working solutions for esters would be helpful. This was difficult to follow.

Method Safety Concerns: No specific issues.

Pros/Strengths: • Gave ranges for times and temperatures, where applicable. Very much appreciated comment about weekend transesterification. • Sonication extraction may speed process a bit. • Includes steps to determine transformation factor to account for the conversion of 3-MCPD into glycidol.

• Utilizes GC-MS which may be more widely available to laboratories • Calculations are much easier to follow than as stated in AOCS method • Method validation very clearly explained

Cons/Weaknesses • Single point calibration based on response of internal standard. This is a risk. A single missed injection or prep error could result in an invalid/missing calibration point. Difficult to verify ongoing method/instrument performance unless the full linear range is assessed in each batch using a multipoint calibration with a minimum of three calibration levels. Instrument performance can certainly decline on the low end, and this will be difficult to monitor otherwise. Also risk of analyst failing to catch linear range exceedance in routine testing without a calibration curve as reference. • Sonication extraction procedure is complicated with differing temperature requirements, depending on the step. Can be confusing. • Identified potential carry over effects in samples containing high levels of free MCPD but stated not likely a potential issue as high incurred free MCPD is rare in infant formula. • Utilizes GC-MS which can be more prone to false positives. Chromatograms typically very clean so not likely a significant issue.

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