Effect of sodium dodecyl benzene sulfonate on the absorption spectrum and determination of crystal violet in aqueous solution

The effect of sodium dodecyl benzene sulfonate (SDBS) on the absorption spectrum of crystal violet (CV) in an aqueous solution was studied by spectrophotometry. The results showed that when the SDBS concentration was lower than the critical micelle concentration (CMC), the absorption spectrum of CV was altered significantly. However, the effect was eliminated when the SDBS concentration was higher than the CMC, and the absorption maximum of the solution gradually reached that of a SDBS-free CV solution. A new method was thus proposed for the determination of the CV concentration in an aqueous solution containing an anionic surfactant. Under the optimal conditions, i.e., a detection wavelength of 584 nm, a SDBS concentration of 4.8 mmol L−1 and a reaction time of 1 h, the linear range of the method was 0.16 × 10−2 mmol L−1–1.6 mmol L−1.