Amino Acids Working Group Meeting Book (November 28, 2017)

Proposed amendment of SMPR for amino acid analysis method

When the original SMPR for amino acid analysis method was considered and determined

by the working group of SPIFAN in 2014, the amino acids data from some commonly used

formula samples were referenced in determining of the range of the concentrations of

amino acids (shown in the spreadsheet labeled “Sample” in attached Excel sheet). When

breaking down the concentrations of amino acids into the three ranges （as in current

SMPR）, the calculations of RSDr and RSD R were shown in the columns of D to K in the

spreadsheet of “SMPR origin” based on the “Guideline of SMPR” of AOAC.

The spreadsheet demonstrated that the RSD for reproducibility was the medium of the

numbers calculated based on the “ideal” RSD for multi-lab testing or 1.5 times of the

predicted RSD from Horwitz formula, while RSD for repeatability was the medium of the

numbers calculated based on the half of the “acceptable” RSD for multi-lab testing based

on the guideline or 2 times of predicted RSD of Horwitz formula.

However, the concentrations used in the calculation by Horwitz formula were 10 times

more concentrated by mistake, see the sheet labeled “SMPR New” in the attached Excel

sheet.

After recalculating the RSDr and RSD R, I propose the amendment of the SMPR as shown

in the sheet labeled “SMPR New” in the attached Excel sheet.

The recovery requirement in the original SMPR matches the guideline.