A facile HPLC method for optical purity and quantitative measurements of phenylalanine from the hydrolyzed aspartame under different pH and temperature after its derivatization with a fluorescent reagent.

In this paper, the artificial sweetener aspartame is deliberately hydrolyzed under different pH and temperature in the matrix, and time period for the hydrolysis. The HPLC analysis is then performed to quantitatively measure the amount and the optical purity of phenylalanine produced as a result of hydrolysis in the matrix after its functionalization with a fluorescent reagent. The results show that the amount of phenylalanine in the matrix is affected by the pH variation during the hydrolysis and found increased in low pH conditions. High temperature or long time periods for the decomposition also increases the amount, which indicates that beverages and foods containing aspartame as a sweetener may not be safe for phenylketonuria patients to consume if they are stored under these conditions. Conversely, the optical purity of phenylalanine, expressed as the percentage of D: -enantiomer, is not affected by pH variations. However, it decreases as the length of time elapsed is increased or surrounding temperature is elevated during the decomposition.