DETERMINATION OF GLUTAMIC ACID AND ASPARTIC ACID IN TOMATO JUICE BY CAPILLARY ISOTACHOPHORESIS

A capillary isotachophoresis method was developed and applied for determination of glutamic acid and aspartic acid in tomato juice samples. The leading electrolyte was 10 mmol L-1 L-histidine monohydrochloride including 1% poly (vinylpyrrolidone) adjusted with histidine to pH 5.5. The terminating electrolyte was 5 mmol L-1 2-morpholineethanesulfonic acid adjusted to pH 6.0 with tris(hydroxymethyl) aminomethane. It was proved that the developed method is suitable for a routine analysis of glutamic and aspartic acid in tomato juice. The simplicity and low cost of this analytical procedure makes the technique a good alternative to high performance liquid chromatography. Usefulness of the method was tested on different varieties of tomatoes as well as different ripeness stages of the fruits. Moreover, commercial tomato juices were also analysed.