适用于所有等级的天然橡胶。该原理基于提取任何游离蓖麻油酸并将蓖麻酸甲酯转化为醋酸盐。提取任何蓖麻油甘油酯，水解为蓖麻油酸，并转化为相应的蓖麻酸甲酯醋酸盐。通过与蓖麻油标准品或蓖麻油标准品水解制备的蓖麻酸进行比较，通过气相色谱法测定总醋酸盐。

Applicable to all grades of natural rubber. The principle is based on extraction of any free ricinoleic acid and conversion to the acetate of methyl ricinoleate. Extraction of any castor oil glycerides also present, hydrolysis to ricinoleic acid, and conversion to the corresponding acetate of methyl ricinoleate. Determination of the total acetate by gas chromatography by comparison either with a ricinoleic acid standard, or with ricinoleic acid prepared by hydrolysis of a castor oil standard.