A UHPLC-PDA method for the quantitative analysis of total amino acids in infant formula with microwave-assisted acid hydrolysis

In this study, a simple and effective analytical method for the determination of 17 total amino acids in infant formula was established and validated. The procedure was based on microwave-assisted acid hydrolysis and conventional alkaline hydrolysis (only for tryptophan) prior to pre-column derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate and quantification using ultra-high-performance liquid chromatography (UHPLC) coupled with photodiode array (PDA) detector. For all amino acids examined, the satisfactory validation results, using certified reference material, were obtained with good linearity (R-2 >= 0.9997), high precision (HorRat < 2), and acceptable accuracy (%R 98-104). The expanded measurement uncertainty for the analytical method were not exceeding 10%. The developed method was also successfully applied to real samples. In summary, the entire outcome indicated that this UHPLC-PDA method is sufficiently appropriate for its intended purpose and can be effectively used in routine analysis for further commercial products quality monitoring program.