<p>A method was established and verified for identifying 315 toxic organic compounds—such as chlorophenols, dyes, pesticides, perfluoroalkyl acids, and fungicides—in waste textile materials and finished products through ultrasound-assisted extraction coupled with high-performance liquid chromatography–tandem mass spectrometry. Acetonitrile was utilized as the extraction solvent in two sequential ultrasonic extraction steps to isolate the analytes from the samples. For liquid chromatography, a C₁₈ column was used for separation. In electrospray ionization positive mode, mobile phase gradient elution was performed with a mixture of acetonitrile and a 0.1% formic acid solution (containing 2&#xa0;mmol/L ammonium acetate) in water. A mobile phase gradient elution using acetonitrile and a 2&#xa0;mmol/L aqueous ammonium acetate solution was applied under electrospray ionization in negative mode, with detection conducted via multiple reaction monitoring (MRM). The analysis revealed that all 315 target compounds maintained strong linearity across their calibration ranges, with correlation coefficients (<i>R</i>²) consistently above 0.9901. The detection limits (LOD) were between 0.01 and 3.8&#xa0;µg/kg, whereas the quantification limits (LOQ) ranged from 0.03 to 10.90&#xa0;µg/kg. Method validation through spiking at concentrations of 10, 20, and 100&#xa0;µg/kg was performed on three sample types: waste cotton lint, waste wool yarn, and waste hemp yarn. The recoveries ranged from 61.3 to 119.9%, with relative standard deviations (RSDs) between 1.1 and 15.9%. Overall, the method offers high sensitivity, accuracy, and reproducibility, rendering it effective for the routine detection of residual organic contaminants in recycled textile materials.</p> Graphical Abstract <p></p>