GB/T 24165-2020 "Determination of Polychlorinated Biphenyls in Dye Products" is applicable to various types of dye products. It employs gas chromatography-mass spectrometry (GC-MS) to determine the residual content of polychlorinated biphenyls (PCBs). The sample undergoes Soxhlet extraction or ultrasonic extraction, followed by purification with concentrated sulfuric acid and separation through a silica gel column before detection. Quantification is performed using the isotope internal standard method. The method specifies the chromatographic column specifications, temperature program, and mass spectrometry detection parameters. The detection limit is 0.05 mg/kg, and the absolute difference between two measurement results should not exceed 20% of the arithmetic mean, ensuring the accuracy and comparability of the test results.