ISO 16265:2009规定了各种水样（如地下水、饮用水、地表水、废水和沥滤液）中亚甲基蓝活性物质（MBAS）指数的测定程序，范围为0.05 mg/l至0.5 mg/l和0.5 mg/l至5.0 mg/l。阴离子表面活性剂是最重要的亚甲基蓝活性物质。因此，该方法可用于估算水的阴离子表面活性剂含量[包括带有羧酸基团的阴离子表面活性剂（例如肥皂）]。其他类型的物质也可能表现出亚甲基蓝活性，并对结果有贡献。根据具体情况，可以改变分析范围，并改变用于其他浓度范围的方法，前提是这些浓度范围正好涵盖十年的浓度单位。

ISO 16265:2009 specifies a procedure for the determination of the methylene blue active substances (MBAS) index, in the ranges 0,05 mg/l to 0,5 mg/l and 0,5 mg/l to 5,0 mg/l, in various water samples (e.g. ground water, drinking water, surface water, waste water and leachates). Anionic surfactants are the most important substances showing methylene blue activity. This method is therefore useful for estimating the anionic surfactant content [including anionic surfactants with carboxylate groups (e.g. soaps)] of water. Other types of substance may also show methylene blue activity and contribute to the result. On a case-by-case basis, the range of the analysis may be changed and the method used for other concentration ranges provided they cover exactly one decade of concentration units.