Quantification by the Spectrophotometric Method of Triclosan in Personal Care Products through Experimental Design

The factorial design was used for optimization of the spectrophotometer method for determining the best conditions to produce an azo compound with higher molar absorptivity and stability. The diazotization reaction of sulphanilamide with triclosan was optimized for the determination of triclosan in samples of personal care products. The diazotization reaction occurs in two steps: (1) reaction of sulphanilamide with sodium nitrite in an acidic medium to form diazonium ion and (2) reaction of diazonium ion and (2) reaction of diazonium ion with triclosan to form a yellowish-orange azo compound in an alkaline medium. The concentration of hydrochloric acid, sulphanilamide and the volume of sodium nitrite were optimized through factorial design of experiments and response surface methodology. The resulting yellowish-orange product showed maximum absorption at 452 nm, which allowed the determination of triclosan in a concentration range of 0.50 mg L-1 to 10 mg L-1 with a correlation coefficient of 0.9994. The limits of detection (LD) and quantification (LQ) were 0.018 mg L-1 and 0.060 mg L-1, respectively. The optimum conditions established by multivariate method produced an azo compound with high optical stability which was successfully applied in the quantification of triclosan in samples of personal care products. This method might be used as an alternative less expensive, easy and simple way to determine triclosan in several personal care products such as toothpaste, body cream and deodorants.