Identification and Determination Methods of Aspartame

Abstract

Objective: To evaluate identification and determination methods of a synthetic sweetener, aspartame.Method: For identification methods, aspartame was tested with ninhydrin solution and with alkaline hydroxylamine solution byusing thin layer chromatogram (TLC). TLC was developed with acetonitrile phosphate buffer. For determination methods,colorimetric method and HPLC method were used.Results: Testing with ninhydrin solution was sensitive (limit of detection was 7.5 mg) but was not specific because this methodwas also able to detect amino acid with a free a-amino group. Testing with alkaline hydroxylamine solution (limit of detectionwas 300 mg) was specific method because it was used to detect carbonyl functional group and formed color complex with ferricchloride. The determination methods were colorimetric method (reaction with ninhydrin solution the same as in identificationmethod) and high pressure liquid chromatographic method (HPLC). The relative standard deviation of colorimetric method ofsimple sugar samples was 5 - 17% and for HPLC method was 3-11%. Percent recovery of these two methods was about 97%.Aspartame was found lower than the labeled amount in many samples and the percent relative standard deviations were largebecause aspartame was a chiral compound and the samples were kept improperly so aspartame may degrade.Key words: identification, determination, aspartameThai Pharm Health Sci J 2008;3(2):214-218§