Stakeholder Panel Meeting Book - September 6, 2014

Analyte Definition

•

Description of the analyte Determination of free and/or total  proteinogenic L‐  ‐amino acids  and taurine in all forms of infant, adult, and/or pediatric formulas  (powders, ready‐to‐feed liquids, and liquid concentrates).  • Rationale Free amino acids are those recovered without depolymerizing the  peptide/protein sample fraction, and may be comprised of any of  those compounds identified in Table 1.  The total concentration of any amino acid includes the free form  plus that released by exhaustive hydrolysis of the sample  protein/peptide component(s). Amino acids reported as part of a  total AA determination may be any of those listed in Table 1,  generally excluding Asn and Gln.

Analyte Definition

•

Rationale (cont.) For samples for which only knowledge of total concentrations is  required, the sums Asp+Asn, as Asp (or, preferably, Asx) and  Glu+Gln, as Glu (or, preferably, Glx), should be reported. For cysteine and cystine, only a single result should generally be  reported, representing the sum of the two. The preferred reporting  format is as cystine, which will almost always be the predominant  form actually present in samples.  Implications:  More than one method, perhaps several, will be required to  capture all of the analytes covered by this SMPR.

•

2