Ultraviolet detection procedure for liquid chromatographic determination of indole in shrimp

In an ultraviolet detection procedure, indole was extracted from shrimp by blending with carbonate buffer and then partitioned into ethyl acetate. Before quantitation by high pressure liquid chromatography (HPLC), interferences were removed by the use of a polyamide cleanup column. Concentrated column effluent was injected into the chromatograph. Indole was detected by monitoring absorbance at 217 nm and quantitated by comparison of indole peak height to that of an internal standard, 2-methylindole. Recoveries of indole ranged from 72 to 117%. Results agreed well with those by the official AOAC gas-liquid chromatographic (GLC) method.