对用作氧化及消解水样并与HE 99721型COD测定仪配套专用的混合试剂溶液的组成进行了试验,最终确定下列组成的混合试剂可适合于代替进口的HI 99955试剂包:0.05 mol·L-1重铬酸钾溶液0.75 mL,硫酸银-硫酸溶液(浓硫酸500 mL中含4 g硫酸银) 1.8 mL及硫酸汞-硫酸溶液(3 mol·L-1硫酸溶液20 mL中含4 g硫酸汞) 0.15 mL,用此自己配制的混合试剂代替进口的试剂包测定了有机废水样品中COD浓度(小于150 mg·L-1),结果表明:分别用两种混合试剂在同一台COD测定仪上所测得结果之间不存在显著差异.

Composition of a reagent mixture for special use in HE 99721 COD determinator as an oxidizing and digestion reagent of the water sample was studied,and a mixed solution containing 0.75 mL of 0.05 mol·L-1 K2Cr2O7 solution,1.8 mL of Ag2SO4-H2SO4 solution (4 g of Ag2SO4 dissolved in and made up to 500 mL of conc.H2SO4) and 0.15 mL of HgSO4-H2SO4 solution (4 g of HgSO4 dissolved in 20 mL of 3 mol·L-1 H2SO4) was found suitable to be used in substitution for the imported HI 99955 reagent package.By using the self-prepared reagent mixture instead of the imported reagent package in the determination of COD in the range within 150 mg·L-1 with the determinator,no significant difference was found between the results using the 2 reagent mixture.