Synchronous spectrofluorimetric determination of naphthalene in water samples using mixed micellar medium

A mixed micellar medium of sodium dodecyl sulfate and Pluronic F-127 was used to enhance the fluorescence of naphthalene and to obtain lower LODs. The method was based upon measuring the first-derivative synchronous fluorescence spectrum of naphthalene by using a mixed micellar medium at a constant wavelength difference delta lambda = 60 nm, where a greater fluorescence enhancement was observed if compared to using a single surfactant separately. A linear fluorimetric calibration curve was obtained for naphthalene in a concentration range of 10-200 ng/mL. The LOD was 7.13 ng/mL, which is well below the health advisory limit for naphthalene in drinking water as suggested by the U.S. Environmental Protection Agency. The method can be easily adopted for determination of naphthalene in aqueous media including tap water and river water. The recoveries obtained were 95.979-115.645%. The proposed method was validated according to International Conference on Harmonization guidelines and successfully applied to determine naphthalene in real life water samples from different sources.