GB/T 23978-2020 "Determination of Chloride in Water-Soluble Dye Products" is applicable to various types of water-soluble dye products and specifies two test methods: ion chromatography and chemical titration. The ion chromatography method uses retention time for qualitative analysis and peak area with external standard method for quantification, with a detection limit of 2 mg/kg. The chemical titration method involves adsorption treatment with activated carbon followed by titration with silver nitrate and ammonium thiocyanate standard solutions. The standard clearly defines sample pretreatment, instrument parameters, and reagent requirements, ensuring that the absolute difference between two measurement results does not exceed 20% of the arithmetic mean, thereby guaranteeing detection accuracy.