样品在酸性条件下回流水解。不可水解的阴离子活性物质通过ISO 2271中描述的直接两相滴定程序测定。本方法适用于测定烷基酚醚硫酸盐中的环磺酸盐和磺化脂肪醇中的少量磺酸盐。如果阴离子物质的含量以质量百分比表示，则必须知道或事先确定阴离子物质的摩尔质量。

The sample is hydrolyzed by refluxing under acid conditions. The non-hydrolyzable anionic-active matter is determined by the direct two-phase titration procedure describes in ISO 2271. This method is applicable to the determination of cyclic sulphonates in alkylphenol ether sulphates and of small amounts of sulphonates in sulphated fatty alcohols. The molar mass of the anionic matter must be known or previously determined, if its content is expressed as percentage by mass.