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通过对比、加标回收和消煮条件实验,比较研究3种混合催化剂在全氮测定中的催化作用效果。研究表明,常规混合催化剂(m(K2SO4)∶m(CuSO4)∶m(Se)=100∶10∶1)作为土壤全氮测定的催化剂,虽然有测定结果稳定、准确度高的优点,但存在着在消煮过程中产生剧毒气体H2Se,对环境和工作人员造成危害的情况,也有分解不完全、结果偏低的可能;国际标准法混合催化剂(m(K2SO4)∶m(CuSO4)∶m(TiO2)=100∶3∶3)的催化作用效果与常规法相比,稳定性差、准确度低;纳米TiO2混合催化剂(m(K2SO4)∶m(CuSO4)∶m(纳米TiO2)=100∶3∶3)的测定结果相对于常规分析法结果偏高,但依其自测的本底值计算回收率在97%～109%,满足农业分析要求,且重现性较好,变异系数均<5%。同时消煮温度低于常规方法,消煮时间短,节能省时、环保、适用范围广泛,是一种有待于开发的新型催化剂材料。
Through the comparison, spike recovery and digestion conditions experiments, the effect of three kinds of mixed catalysts on the determination of total nitrogen was comparatively studied. The results show that the conventional mixed catalyst (m 2 SO 4: m (CuSO 4): m (Se) = 100: 10:1) has the advantage of stable determination and high accuracy In the process of digestion and cooking produces toxic gas H2Se, harm to the environment and the staff, but also incomplete decomposition, the results may be low; international standard method mixed catalyst (m (K2SO4): m (CuSO4): m (TiO2) = 100: 3: 3) has the poor stability and low accuracy compared with the conventional method. The photocatalytic activity of TiO2 / : 3) was higher than the results of routine analysis, but the recovery rate was 97% -109% according to the background value of self-test, which met the requirements of agricultural analysis and the reproducibility was good with the coefficients of variation < 5%. At the same time, the temperature of digestion and digestion is lower than the conventional method, the time of digestion and digestion is short, energy saving and time saving, environmental protection and wide range of application are a new type of catalyst material to be developed.