RESUMO
The resonance light scattering (RLS) spectral characteristics of the interaction between rose Bengal and mexiletine hydrochloride in the presence of cetylpyridinium bromide were investigated. A dual-wavelength resonance light scattering (DWO-RLS) method for the determination of mexiletine hydrochloride in drugs was established. In a weakly acidic solution, rose Bengal interacts with mexiletine hydrochloride and cetylpyridinium bromide to form a red ternary ion association complex, which led to a significantly enhanced resonance light scattering signal and produced two strong characteristic scattering peaks at 372 nm and 596 nm. In these two wavelengths the mass concentration of mexiletine hydrochloride was in the range of 0.004 to 0.65 mg·L-1 and had a good linear relationship with the resonance light scattering enhancement intensity (ΔIRLS), with detection limits of 0.003 2 mg·L-1 (372 nm) and 0.003 8 mg·L-1 (596 nm), respectively. When measured by the dual-wavelength resonance light scattering (DWO-RLS) technique, the detection limit was lower, only 0.001 8 mg·L-1. When the DWO-RLS method was applied to the determination of mexiletine hydrochloride in commercially available mexiletine hydrochloride tablets, and the recovery was 98.5%-103%, and the relative standard deviation was 2.0%-2.7%.
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.