Chinese Herbal Medicine Residue‐Derived Biochar Assisted Matrix Solid Phase Dispersion Microextraction of Synthetic Dyes From Lake Sediments Using Supramolecular Solvents as Dispersing Solvents

ABSTRACT In this study, a new matrix solid‐phase dispersion (MSPD) method was developed and applied to extract auramine O (AO) and rhodamine B (RB) from sediment samples. A new supramolecular solvent (SUPRAS) composed of hexafluorobutanol (HFB) and linaool was used as the dispersing solvent of MSPD. Biochar, obtained by pyrolysis of a Chinese medicine residue namely Sophora japonica L., was used as the dispersing sorbent of MSPD procedure. Parameters influencing the extraction efficiency including the type and volume of dispersing solvent, amount of dispersing sorbent, grinding period, and vortex time were investigated and optimized. Under the optimized conditions, the linear range of the target analytes was 3–400 µg g −1 with correlation coefficients higher than 0.9964. The method provided low limits of detection and limits of quantification, and excellent precision (intra‐ and inter‐day analysis with relative standard deviations below 5.5%). Finally, the proposed method was applied to determine the synthetic dyes in Dianchi Lake sediments with satisfactory extraction recoveries of 93.5%–105.1%, indicating the applicability for the determination of synthetic analytes in real samples. Compared with the traditional sample preparation method for sediment samples, the proposed method reduced the extraction time, sample, and organic solvent usage. The proposed method is easy, fast, and green and can be applied to determine various analytes in sediment samples.