A procedure for the mutual derivatization and determination of thymol and Dapsone was developed and validated in this study. Dapsone was used as the derivatizing agent for the determination of thymol, and thymol was used as the derivatizing agent for the determination of Dapsone. An optimization study was performed for the derivatization reaction; i.e., the diazonium coupling reaction. Linear regression calibration plots for thymol and Dapsone in the direct reaction were constructed at 460 nm, within the concentration range of 0.3-7 μg ml-1 for thymol and 0.3-4 μg ml-1 for Dapsone, with limits of detection 0.086 and 0.053 μg ml-1, respectively. Corresponding plots for the cloud point extraction of thymol and Dapsone were constructed at 460 nm, within the concentration range of 0.1-2 μg ml-1 for thymol and 0.1-1.8 μg ml-1 for Dapsone, with limits of detection 0.0445 and 0.023 μg ml-1, respectively. Correlation coefficients and molar absorptivities were improved using cloud point extraction. The proposed method can be applied for their trace detection in different matrices.
