Investigation of the Influence of Sodium Salicylate and Sodium Benzoate Hydrotropes on the Solubility of Quercetin and Piperine: Experiment and Computational Study

In this work, the solubility of quercetin and piperine was studied using sodium salicylate and sodium benzoate as hydrotropes. The hydrotrope concentration was varied from 0 to 3.0 mass fraction of hydrotropes in the solutions at a temperature range of 303–333 K. The solubility of quercetin and piperine increased with increasing concentrations of hydrotropes and an increase in temperature. The solubility of quercetin and piperine was insignificant until the minimum hydrotropic concentration was reached. However, the solubility of quercetin and piperine increased drastically up to the maximum hydrotrope concentration (Cmax) owing to the aggregation of molecules upon mixing, which further enhanced their solubility in aqueous hydrotrope solutions. The maximum solubility of quercetin and piperine was found to be 14.651 mmol·L–1 with 0.3245 mass fraction of hydrotropes at 313 K and 3.301 mmol·L–1 with 0.3245 mass fraction of hydrotrope sodium salicylate solution at 333 K. The solubility data of quercetin and piperine in the hydrotrope solutions at different temperatures were fitted by the modified Gompertz model equation. Further, the σ profile and σ potential of all of the studied components were generated using the COSMO-RS model.