Stakeholder Panel Meeting Book - September 6, 2014

Stakeholder Comments 2.   The NIST 1849a table line 81. Arginine is listed twice. Actually I would suggest removing the  NIST 1849a data from the SMPR altogether The reason for this is how confident are we that the .  reference values for the NIST standards are accurate for all amino acids? There are two facets to  this question. The first is that traditional methods for determining amino acids (ie, 24 hr HCl  hydrolysis at 110oC for the bulk of the amino acids, performic acid oxidation/HCl hydrolysis for  cysteine and methionine and base hydrolysis for tryptophan) do not accurately determine all  amino acids. For example, serine and threonine can be underestimated by as much 10‐15% and  some of the branched chain amino acids are difficult to hydrolysis and can be underestimated by  up to 10%. If traditional methods have been used to determine the amino acid composition of  the NIST 1849a then some of the values may not be accurate. The second facet relates to the fact  that if the NIST 1849a has been prepared in a similar way to regular infant formulas/adult  nutritionals then it potentially contain amino acids that have been modifies during the processing  of the material and if present, it is quite possible that some of these modified derivatives  interfere with the accurate determination of some amino acids. 

Stakeholder Comments 2.(cont) Arginine is not listed twice, the upper one is Alanine. It is true that the labeled reference  values of each amino acid for the NIST 1849a may be not as accurate as it should be when using  more advanced, more scientifically sound methodology. Some may change, how much we don’t  really know, as more research/discovery is made.   For most of the amino acids, there is really no  special reason to suspect that the data may inaccurate.  If results for select amino acids change  based on updated methodology, we would hope that NIST might issue a revised certificate or an  addendum.   We believe that, despite the potential gaps, NIST 1849a remains the best choice as a  relevant SRM.

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