Improved Diazotization-coupling Technique for Analysis of Methyl Anthranilate in Grape Products

Methyl anthranilate was determined in grape products by diazotizing with 1M HC1 and 1% sodium nitrite and coupling the diazonium salt with N-1-naphthylethylenediamine dihydrochloride in situ. The chromophore which formed had an extinction coefficient of 42,000 mole^?1L cm^?1 and color formation correlated with concentration in accordance with Beer's Law up to about 100 μg methyl anthranilate. Grape essence samples with 3 to 124 μg mL^?1 methyl anthranilate were used to evaluate the method against a gas chromatographic technique. The correlation coefficient was >0.99 between the two methods. Compared with existing methods, this new method has the advantage of not requiring stringent reaction times or conditions.