[Simultaneous determination of phenol and resorcinol by dual-wavelength spectrophotometric linear regression method].

Spectrophotometric simultaneous determination of phenol and resorcinol was studied. The absorption spectra of these two components severely overlap in ultraviolet spectral range. In the wavelength range of 250-290 nm, the absorbances of phenol and resorcinol were measured with an internal of 0.5 nm. Two wavelengths at 280.5 and 273.5 nm were chosen for the determination. Dual-wavelength linear regression method was used for the determination of phenol and resorcinol. Twenty five mixture standard solutions were prepared according to the orthogonal projection form L25 (5(6)). Two kinds of the components were linearly regressed. Meanwhile the contents of phenol and resorcinol in six synthetic mixture samples and simulation pharmaceutical preparations were measured. The measurement results showed that the relative error of phenol and resorcinol were less than 5%. The measurement system is stable and reliable. Therefore, the dual-wavelength spectrophotometric linear regression method may provide a new approach to the determintion of phenol and resorcinol in their compound preparations.