Spectrophotometric Determination of Copper and Lead with Phenylfluorone and Benzyldimethyltetradecylammonium Chloride

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The complexation reactions of copper(II) and lead(II) with phenylfluorone in aqueous micellar solutions of different surfactants were investigated. Maximum sensitization of the color reactions was obtained in the presence of benzyldimethyltetradecylammonium chloride (Zephiramine). The sensitized 1:2 copper- and lead-phenylfluorone chelates were formed within the pH ranges 8.8-9.8 and 8.8-9.5, with molar absorptivities of 9.3×10⁴ and 6.2×10⁴M^-1 cm^-1, respectively. Beer′s law was obeyed up to 0.42ppm of copper and 1.96ppm of lead at 562nm. The sensitivity indexes were 0.0007μg cm-2 (Cu) and 0.0033μg cm^-2 (Pb). The developed methods were successfully applied to determine copper and lead in some double-base propellants. Moreover, a two-step procedure was proposed to determine copper and lead mixtures, through the reaction of two increments of a mixture with phenylfluorone and Zephiramine at pH 9.0±0.1, in both the absence and presence of thiourea as a selective masking agent for copper.