Development of a sensitive and reproducible method for analysis of 22 underivatized amino acids and application of the method to quantify 17 amino acids in wine. Accurate quantification of proline, using an isotopically labeled internal standard.
In this Application Update, we combine into a single method individual improvements made to the standard AAA-Direct gradient program. These individual improvements are now in the AAA-Direct manual. This update shows that such combined changes to the AAA-Direct method improve the performance of our previously published method. This new method successfully determines amino acids in yeast extract-peptone-dextrose yeast culture medium (YPD Broth), and Dulbecco’s modified Eagle’s (with F-12), M199, L-15 (Leibovitz), and McCoy’s 5A media for mammalian cell culture.
In this technical note, we describe a procedure to screen sample matrices for their effect on peak area, peak height, and retention time. We demonstrate this procedure by testing ethanol for possible interferences in AAA-Direct. However, the method described here can also be used to evaluate any matrix component analyzed by chromatography with electrochemical detection. In this technical note, we use the term test sample (TS) to describe the specific test compound evaluated for possible interferences.
This Technical Note describes the peptide hydrolysis procedures that lead to successful determinations of amino acid composition using AAA-Direct. Results for the amino analysis of two peptides, Melanocyte Stimulating Hormone (MSH) and Luteinizing Hormone-Releasing Hormone (LH-RH), using both hydrochloric acid and methanesulfonic acid (MSA) as hydrolyzing reagents are presented to demonstrate the performance of this method.
This application note shows that AAA-Direct can be used to determine peptides with lysine hydroxylation. All common amino acids, including hydroxylysine (Hyl), were separated by AAA-Direct, and the presence or absence of Hyl in the fractions confirmed peak identities. The techniques described in this application note show several ways that peptides can be evaluated for identity and purity, how peptides can be desalted, and how much desalting is needed for successful AAADirect amino acid analysis.
