几种凯氏加速剂对植物全氮消煮时间和结果的比较分析

Comparation and Relative Analyses on the Digesting Time and Results of Catalyst Mixtures of Plant Total Nitrogen in Kjeldahl Method

探讨了几种凯氏加速剂对植物全氮的消煮测定情况,浓H2SO4分别加入K2SO4+CuSO4、H2O2、K2SO4+CuSO4+Se和Na2SO4+Se对苜蓿、高丹草、狼尾草、油菜花粉等4种植物材料进行消煮和测定,统计结果表明:消煮液在380℃消煮清亮后继续加热120 min,测定的全氮差异显著,K2SO4+CuSO4、K2SO4+CuSO4+Se和Na2SO4+Se分解出的氮较多,加入H2O2氧化分解出的氮少;含Se的加速剂消煮所需时间最短,H2SO4加入H2O2消化速度最慢;样品消煮清亮后应继续加热40 min以上;用Na2SO4+Se作加速剂代替H2SO4+H2O2可同时测定植物氮磷钾。

Several catalyst mixtures were studied about digesting conditions of plant total nitrogen, four kinds of catalyst mixtures used for the plant analysis of total nitrogen by J. Kjeldahl method were compared, four kinds of botanical materials including Purple medic, Sorghum hybrid Sudan grass, Kikuyu grass and Rape pollen were digested. The total Nitrogen obtained at digestion temperature of 380℃ were significant different among K2SO4 ＋ CuSO4, H2O2, K2SO4 ＋ CuSO4 ＋ Se and Na2SO4 ＋ Se after clearing 120 min. Cone. H2SO4 with K2SO4 ＋ CuSO4 ＋ Se, K2SO4 ＋ CuSO4 or Na2SO4 ＋ Se decomposed out more N than H2O2 ; it took less time for the catalyst mixtures containing Se to digest the plant tissues to clear, H2SO4-H2O2 method was slowest; Digestion should be at 380℃ for an additional 40 minutes after clearing to ensure complete reaction; Compared with H2SO4 ＋ H2O2, Na2SO4 ＋ Se was more convenient for determining plant total N, total P and total K simultaneously.