Determination of a cationic surfactant with naphthalene black 12B by the resonance light scattering technique

A new determination method for a cationic surfactant, zephiramine (Zeph), was developed with resonance light scattering (RLS) technique, based on the interaction of naphthalene black 12B with Zeph. The resonance light scattering (RLS) and UV characteristics of interaction between naphthalene black 12B and Zeph were studied. The RLS intensity of naphthalene black 12B at 363 nm was greatly enhanced in the presence of Zeph at pH 6.0. The enhanced RLS is proportional to the concentration of Zeph in the range of 3.20 x 10(-7) - 1.44 x 10(-5) mol L(-1). The limit of detection was 8.8 x 10(-8) mol L(-1). The proposed method was applied to the determination of Zeph in synthetic and spiked water samples with the recovery of 96.2-104% and RSD of 1.1-2.5%.