1574 Jaudzems et al.: Journal of aoaC InternatIonal Vol. 102, no. 5, 2019 common proteinogenic amino acids. Amino acids may be present either in their free forms or bound as part of the protein/ peptide component. Although cysteine fts the general structure for α-amino acids, its disulfde form, cystine, is obviously included in the working defnition of amino acids. The two are equivalent from a nutritional point of view, and regulations treat them as such. Because of method overlap, taurine (Tau; 2-amino- ethanesulfonic acid) is also included in this analyte category, despite not ftting the basic defnition. In terms of nutritional signifcance, α-amino acids primarily refect protein quality, because in nutritional products the protein is a vehicle for delivering amino acid substrates for protein synthesis. Free amino acids substitute for protein in elemental formulas (Table 1). Total AA analysis requires hydrolysis and analysis steps. Each step introduces its own complications: (1) complex collection of molecular structures; (2) no common structural features compatible with direct, sensitive detection; (3) asparagine (Asn) and glutamine (Gln) are converted to aspartic acid (Asp) and glutamic acid (Glu) during acid hydrolysis, resulting in a summed determination; and (4) as of this publication, no single method can release all of the amino acids from protein (cystine and tryptophane are destroyed during acid hydrolysis). AOAC Offcial Method 2018.06 Total Amino Acids by UHPLC–UV in Infant Formulas and Adult Nutritionals First Action 2018 Quantitative determination of total amino acids using 6-aminoquinolyl-N-hydroxy succinimidyl carbamate (AQC) derivatization followed by ultrahigh-performance LC (UHPLC) separation and UV detection. This method allows the determination, in one single analysis, of the following amino acids: alanine, arginine, aspartic acid (combined with Asn), cystine (dimer of cysteine, combined with cysteine), Glu (combined with Gln), glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, Tau, threonine, tyrosine, and valine. This method is not suitable for the determination of tryptophan. [Applicable to infant and adult/pediatric nutritional formulas and other matrices such as infant cereals and pet foods.] Caution: Refer to Material Safety Data Sheets prior to use of chemicals. Use appropriate personal protective Total Amino Acids by UHPLC–UV in Infant Formulas and Adult Nutritionals, First Action 2018.06 GreG Jaudzems and Joseph Guthrie Nestlé Quality Assurance Center, 6625 Eiterman Rd, Dublin, OH 43017 sabine Lahrichi and christophe Fuerer Société des Produits Nestlé SA, Nestlé Research, Route du Jorat 57, 1000 Lausanne 26, Switzerland Received February 4, 2019. Accepted by SB June 10, 2019. INFANT FOrMULA ANd AdULT NUTrITIONALs Background: An acid hydrolysis ultrahigh- performance LC–UV method was evaluated for the determination of total amino acids in infant formula and adult/pediatric nutritional formula. Objective: It was assessed for compliance against AOAC INTErNATIONAL Standard Method Performance Requirements (sMPr ® ) established by the stakeholder Panel for Infant Formula and Adult Nutritionals (sPIFAN). Methods: A single-laboratory validation (sLV) study was conducted as a frst step in the process to validate the method. In this sLV, 17 sPIFAN matrices representing a range of infant formula and adult nutritional products were evaluated for their amino acid content. Results: The analytical range was found to be within the needs for all products; some may require a dilution. Evaluation of trueness performed on standard reference Material 1849a (Infant/Adult Nutritional Formula) showed all compounds met the sMPr theoretical value, with exceptions for threonine and tyrosine. These may have a bias for the National Institute of standards and Technology (NIsT) data, depending on hydrolysis used in the determination of the NIsT certifcate of analysis. Conclusions: Based on the results of this sLV, this method met the sMPr and was approved as a First Action method by the AOAC Expert review Panel on Nutrient Methods on August 28, 2018. F or the purposes of this method, the term “amino acids” (AA) refers primarily to L-α-amino acids of the general structure (except proline): specifcally, the twenty DOI: https://doi.org/10.5740/jaoacint.19-0036 This method was approved by the AOAC Expert Review Panel for Nutrient Methods as First Action. The Expert Review Panel invites method users to provide feedback on the First Action methods. Feedback from method users will help verify that the methods are ft-for-purpose and is critical for gaining global recognition and acceptance of the methods. Comments can be sent directly to the corresponding author or methodfeedback@aoac.org. Appendixes are available on the J. AOAC Int. website, http://aoac. publisher.ingentaconnect.com/content/aoac/jaoac Corresponding author’s e-mail: Greg.Jaudzems@us.nestle.com Downloaded from https://academic.oup.com/jaoac/article/102/5/1574/5658373 by guest on 09 August 2021