在环境温度下蒸发试验部分，并用四氯化碳萃取残余物中的油。通过蒸发有机溶剂和称量残留物，或通过在约3.42 m的波长下对有机相的吸光度进行光谱测量，以重量法测定残留物中所含的油。重量法适用于油含量等于或大于10 mg/kg的产品。红外光谱测定法更灵敏，适用于油含量大于1 mg/kg的产品。

A test portion is evaporated at ambient temperature and the oil contained in the residue is extracted with carbon tetrachloride. The oil contained in the residue is determined either gravimetrically by evaporation of the organic solvent and weighing of the residue or by spectrometric measurement of the absorbance of the organic phase at a wavelength of approximately 3.42 m. The gravimetric method is applicable to products having an oil content equal to or greater than 10 mg/kg. The infra-red spectrometric method, being more sensitive, is applicable to products having an oil content greater than 1 mg/kg.