GB/T 38722-2020 "Surface active agents — Determination of interfacial tension — Pulling liquid membrane method" specifies the method for determining interfacial tension by the pulling liquid membrane method. It is applicable to two-phase liquid systems containing anionic or nonionic surfactants and is not suitable for cationic surfactant systems. The test requires the use of a tensiometer (including a stirrup ring/ring and a dynamometer) with an accuracy of not less than 0.1 mN/m, a measurement cup with a diameter of ≥8 cm, and a pipette with an accuracy of 0.05 mL. Under constant temperature conditions, the interfacial tension is calculated by measuring the maximum force when the liquid membrane is pulled, providing a basis for the evaluation of surfactant performance.