alpha-Aspartame (L-alpha-aspartyl-L-phenylalanine methyl ester) is increasingly being used in wide variety of commonly consumed food products. This structure contains ester and peptide bonds. The ester linkage may hydrolyze to produce L-alpha-aspartyl-L-phenylalanine or cyclohydrolyze to produce the corresponding cliketopiperazine ring. This ring can open to form L-alpha-aspartyl-Lphenylalanine and ultimately this compound can hydrolyze to L-phenylalanine and L-aspartic acid. The pH, buffer type, concentration, the presence of water and temperature are other important factors affecting its stability. Because a-aspartame can lose its sweetness under these conditions determination of aspartame and its breakdown products is extremely important for diet foods quality.