RESUMO
Objective: To establish a simple,rapid and novel Rayleigh light scattering(RLS)method for rapid determination of mexiletine hydrochloride in drugs. Methods: In the presence of acid Tris-HCl medium and cetylpyri- dinium bromide,eosin Y reacted with mexiletine hydrochloride to form a ternary ion association complex with two charac- teristic scattering peaks by electrostatic attraction. The detection wavelengths were 368 and 586 nm. There was a linear relationship between the mexiletine hydrochloride concentration in a certain range and the Rayleigh light scattering en- hancement intensity(ΔIRLS)of the association complex. Single-wavelength Rayleigh scattering(SWO-RLS)method or dualwavelength Rayleigh light scattering(DWO-RLS)method was used to determine the content of mexiletine hydrochloride, and the mexiletine hydrochloride content was calculated according to the regression equation of standard curve. Results: The linear ranges of mexiletine hydrochloride were 0.005-0.65 mg/L(SWO-RLS method,368 nm),0.004-0.65 mg/L (SWO-RLS method,586 nm)and 0.004-0.65 mg/L(DWO-RLS method,368 nm+586 nm),respectisely. Detection lim- its were 0.0033(SWO-RLS method,368 nm),0.0040(SWO-RLS method,586 nm)and 0.0018 mg/L(DWO-RLS method, 368 nm+586 nm),respectisely. The recovery and relative standard deviation(RSD,n=5)for a SWO-RLS method were 98.6-103% and 1.4-1.8%,respectively(SWO-RLS method,368 nm). Conclusion: The method is simple,rapid, highly sensitive and high selectie.