Abstract: In pH 5.9 NaAc-HAc buffer medium, famotidine (FMTD) reacted with Hg (II) to form chelate cation ([Hg(FMTD)]2+), which further reacted with anionic surfactants (AS) such as sodium dodecylsulfate (SLS), sodium dodecylbenzene sulfonate (SDBS) and sodium dodecylsulphate (SDS) to form ternary mixed coordination compound([Hg(FMTD)(AS)2]). As a result, the resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) were enhanced greatly. Their maximum wavelengths were located at 345~352 nm, 544 nm and 352 nm, respectively. The three scattering intensity (ΔI) were proportional to the FMTD concentration in a certain range and the detection limits were 3.3~3.9 ng/mL (RRS method), 14.6 ~ 16.3 ng/mL (SOS method) and 7.0 ~ 8.5 ng/mL (FDS method). Based on it, a sensitive, good selective, simple, rapid and new method had been proposed to determine FMTD. It can be applied to determine FMTD in injection, serum and urea sample. The formative mechanism of[Hg(FMTD)(AS)2] was discussed, the effects of formation of [Hg(FMTD)(AS)2] on absorption and RRS spectra were investigated, the reasons of enhancement for RRS was also discussed.

Key words: famotidine, Hg (II), anionic surfactant, resonance Rayleigh scattering, second-order scattering, frequency doubling scattering