Determination of the decomposition products of Usal in model systems and determination of dioxopiperazine in soft drinks by HPLC

Abstract

A HPLC method for the determination of Usal (Aspartame hydrochloride, L-aspartyl-L-phenylalanine methyl ester hydrochloride) and its decomposition products was elaborated. Aspartic acid, phenylalanine, phenylalanine methyl ester, aspartyl-phenylalanine, phenylalanyl-aspartic acid, 5-benzyl-3,6-dioxo-2-piperazineacetic acid (DOP) and Usal were separated on Separon SI C-18. The mobile phase was: 0.5 M NaH2PO4 (pH 2.1) and methanol (85:15 v/v). The detection was carried out at 200 nm. The method for DOP determination was tested by the analysis of 10 types of soft drinks to which DOP was added. In two newly developed sorts of soft drinks sweetened with Usal the formation of DOP was followed during storage. The DOP increment after 34 days of storage reached 0.7 and 6 mg/l at 7 and 20 degrees C, resp. The method is also suitable for DOP determination in the sweetener itself.

Determination of aspartic acid, phenylalanine, and aspartylphenylalanine in aspartame-containing samples using a precolumn derivatization HPLC method

“…High-performance liquid chromatography is an extremely useful method for the separation of amino acids and peptides, and many HPLC assays have been reported for the analysis of APM (Prudel and Davidkova, 1985; Tsang et al, 1985; Verzella and Mangia, 1985; Argoudelis, 1984; Daniels et al, 1984;Tyler, 1984;Webb and Beckman, 1984;Cross and Cunico, 1984;Fox et al, 1976;Furda et al, 1975; Hussein et al, 1984). However, the levels of * To whom correspondence should be addressed.…”