ABSTRACT
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%.
ABSTRACT
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.
ABSTRACT
OBJECTIVE: To establish a new resonance Rayleigh scattering method for the fast determination of captopril in drug and biological samples. METHODS: In a Tris-hydrochloric acid buffer solution of pH 9.05, quantitative methods of determination of captopril in drug and biological samples were studied by resonance Rayleigh scattering technology with brilliant green as probe. The detection wavelength was set at 368 nm. RESULTS: In the weak alkaline Tris-hydrochloric acid medium, captopril reacted with brilliant green to form a green binary ionic association complex, which led to a quench effect of the system's resonance rayleigh scattering (RRS). The maximum resonance Rayleigh scattering peak was located at 368 nm. At this wavelength, the system's RRS quenching degree was directly proportional to the mass concentration of captopril in the range of 0.005 to 0.43 mg•L-1 with the detection limit of 0.004 8 mg•L-1. The recovery and RSD (n = 6) were found to be 98.95% - 102.0% and 1.6% - 2.3%, respectively. CONCLUSION: The method is simple, rapid and sensitive, which was applied to determine the contents of captopril in commercially available captoril drugs and in human blood and urine with satisfactory results.