2
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.
