为测定水样的CODMn值,取水样及空白水样各100.0 mL,分别置于锥形瓶中,经硫酸溶液酸化后,各加入2.0×10-3mol·L-1高锰酸钾溶液18.00 mL,在水浴中加热反应10 min。将试液冷却并离心分离水样中不溶杂质,于波长525 nm处,以1 cm比色皿,用水作参比,分别测量空白溶液及样品溶液的吸光度A0及A,两者的差值ΔA(A0-A)即为与水中还原性物质反应所消耗的高锰酸钾。样品的CODMn值可从CODMn标准溶液所制作的校准曲线上查得。

For determination of CODMn of water sample, 100.0 mL each of water sample and blank water sample were taken and placed in conical flasks separately. After acidifying with H2SO4 solution, 18.00 mL of 2.0×10-3mol·L-1 KMnO4 solution were added to each of the flasks and the solutions were heated in a water bath for 10 min. After cooling and centrifuging, absorbances A0 and A of the supernatants were measured at 520 nm with 1 cm absorption cell vs. H2O as reference. Difference of absorbances ΔA(A0-A) represents the amount of KMnO4 consumed by its reaction with the reducing substances present in water sample. Value of CODMn of the sample was found from the calibration curve prepared by standard solution of CODMn.