[Spectrometric study on the interaction of doxepin hydrochloride and fast green and its application].

The characteristics of resonance light scattering and absorption spectra of doxepin hydrochloride with fast green were investigated, and a new analytical method for doxepin hydrochloride was described. In the buffer solution of pH 4.0, doxepin hydrochloride can strengthen the signal of resonance light scattering of fast green. The effective factors, including the order of addition of the reagents, acidity and kinds of the buffers, and concentration of fast green were investigated. Under the optimum conditions, the scattering peaks of the system are at 344 and 486 nm, while the maximum is at 344 nm. The enhanced intensity of RLS is proportional to the concentration of doxepin hydrochloried in the range of 8.75 x 10(-3)-4.88 x 10(-2) mg x mL(-1). The detection limit for doxepin hydrochloried is 1.72 x 10(-5) mg x mL(-1). The relative standard deviation obtained from eleven determinations for a 0.025 mg x mL(-1) standard solution of doxepin hydrochloried is 1.4%. The method was applied to the determination of doxepin hydrochloric in pharmaceutical preparations. The results were compared with those obtained by the reference method, and t-test showed no significant difference between the two methods.