Application of ultrasonication for facilitating the extraction of hippuric acid and methyl hippuric acid in real samples using Fe3O4@SiO2@sodium dodecyl sulfate: experimental design methodology

This study is centered around establishing an efficient, simple and reliable surfactant assisted dispersive micro solid-phase extraction method followed by the accurate trace determination of HA and MHA as biomarkers for exposure to toluene and xylene. To achieve the above goal, Fe3O4@SiO2@sodium dodecyl sulfate was employed for the extraction of two compounds from various environmental water and urine samples. Due to its superb dispersibility and appropriate structure after modification by SDS, the Fe3O4@SiO2@SDS sorbent exhibited a great deal of improvement in the extraction efficiency. Once the extraction of analytes had been achieved, they were desorbed from the sorbent using an appropriate solvent followed by high-performance liquid chromatography with ultraviolet detection (HPLC-UV). Under the optimal extraction conditions, the calibration curves for the analytes were linear over the concentration range of 1-1000 g L-1 for water media and 5-4000 g L-1 for urine media. The accuracy of the method was tested by relative recovery experiments on fortified real samples with the results falling within the range of 96 to 103.3%. Based on a signal-to-noise ratio of 3 (S/N = 3), the method detection limits were determined to be 0.2 g L-1 and 0.5 g L-1 for HA and MHA, respectively.