Decomposition in foods (chemical methods). Fluorometric determination of indole in shrimp.

A fluorometric method is described for determining indole in shrimp. The indole is extracted with n-hexane, partitioned into a methanol-saturated sodium chloride solution (9+1), and determined fluorometrically. The detection limit of the method is 0.04 microgram indole/g shrimp. Quantitative analytical data are presented for indole in samples of shrimp determined by the fluorometric method and the AOAC official colorimetric and gas-liquid chromatographic procedures. The correlation coefficient between the data of the fluorometric and colorimetric methods was 0.96. Indole recovered from 25 g samples of fresh shrimp spiked with 6 and 12 microgram indole/25 g ranged from 97 to 106%. The fluorescence response is linear in the range of 1 to 25 microgram indole/100 ml methanol solution and no significant change is noted in solutions kept in the dark 18 hr.