DIRECT-DETECTION OF MALACHITE GREEN IN TISSUES OF FISH BY REFLECTANCESPECTROFLUOROMETRY AT 77 K

A new analytical method to detect a fungicide, the malachite green, in tissues of edible fish (rainbow trout, Onchoryhnchus mykiss) is descr ibed. It is based on the physical property of dye to give an intense f luorescence emission at 77 K in the visible region (lambda max = 640 n m) where any emission due to the substrate is observed. This allows a direct investigation of the tissues of the treated fish by reflectance spectrofluorimetry in solid state. The detection limit is estimated t o be in the range of 0.005 ppm, 100 times lower than the detection lim it given by the standard chromatographic method using spectroscopic ab sorption measurement. The reflectance spectrofluorimetry detection see ms interesting for a local determination of the concentration of malac hite green in the different parts of the fish where it could accumulat e.