适用于含量等于或大于0.05%（m/m）（火焰原子吸收法）或0.1%（m/m）（荧光吸收法）的产品。涵盖了双缩脲和硫酸铜（II）在碱性介质中形成络合物的过程。将该复合物固定在阴离子交换树脂上。先用硝酸钾溶液洗脱铜，然后用硝酸溶液洗脱。火焰原子吸收:将溶液吸入乙炔空气火焰中，并测量铜空心阴极灯发出的325 nm线的吸收；或通过光度吸收:在铜和二苄基二硫代氨基甲酸锌之间形成有色络合物，用四氯化碳萃取，并在约435 nm波长下测量。 也得到了IUPAC的批准。

Applicable to products having contents of equal to or more than 0.05 % (m/m) (with flame atomic absorption) or 0.1 % (m/m) (with fotometric absorption). Covers the formation of a complex between biuret and copper(II) sulphate in alkaline medium. Fixation of this complex on an anion exchange resin. Elution of Cu first with a potassium nitrate solution and then with a nitric acid solution. Flame atomic absorption: aspiration of the solution into an acetylene-air flame and measurement of the absorption of the 325-nm line emitted by a copper hollow-cathode lamp; or by photometric absorption: formation of a coloured complex between Cu and zinc dibenzyldithiocarbamate, extraction with carbon tetrachloride and measurement at a wavelength of about 435 nm. Has also been approved by the IUPAC.