根据试样在水中的溶解，用碱溶液置换后蒸馏氨水。吸收过量的标准体积硫酸溶液，并在甲基红/亚甲基蓝混合指示剂存在下用标准体积氢氧化钠溶液反滴定。典型的蒸馏装置如图所示。

Based on dissolution of a test sample in water, distillation of the ammonia after displacement by an alkali solution. Absorption in an excess of standard volumetric sulphuric acid solution and back-titration with standard volumetric sodium hydroxide solution in the presence of methyl red/methylene blue mixed indicator. A typical distillation apparatus is shown in a figure.