Development of new methods for determination of toxic chemical residues in aquatic systems has received considerable interests in recent years. Brilliant green (BG) [4- (Diethylamino) cyclohexa-2,5-dien-1-yliden] diethyl ammonium hydrogen sulfate is a dye in the triphenylmethane family that has antifungal properties [1]. The toxicity of (BG) in many countries, have prohibited the use of this dye in fish raised for human consumption. The use of BG more than standard range has caused enviromental contamination and affected human health and for example causen carcinogenic and mutagenic properties. In this research a novel kinetic spectrophotometric method for the accurate and sensitive determination of BG has been reported [2]. The method is based on selective interaction of (BG) with triton x-100. The interaction was monitored spectrophotometrically by measuring the change in BG absorbance (∆A) at 634 nm during the variable times of 0 to 900 s. The effect of variables on the interaction rate of BG and triton x-100 were investigated in order to establish the optimum conditions. Brilliant green can be measured in the linear range of 1.0 to 12.0 μg mL-1 with detection limit of 0.047 μg mL-1. The relative standard deviations for five replicate in three levels of BG concentration (2, 6 and 10 μg mL-1) were of 1.75% to 8.18 %. This method was used to BG determination in simulated textile dye effluent and goldfish farming water with satisfactory results.

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