碱性过硫酸钾氧化法测定溶液中全氮含量氧化剂的选择

对碱性过硫酸钾氧化法测定溶液中全氮含量采用的氧化剂进行了比较研究。结果表明，氧化反应过程中溶液的pH值与氧化剂的效果有密切关系;氧化剂中过硫酸钾与NaOH配比合适，有利于溶液中的氮素转化为NO3--N。3％过硫酸钾与0.15mol.L-1NaOH配合是一个适宜的氧化剂，可测定的尿素最大浓度为N，80mgL-1，可定量地回收L-丙氨酸及EDTA溶液所含的氮素，测定的0.5mol.L-1K2SO4土壤浸提液中的全氮与开氏法结果基本一致。

CHOOSING OF A PROPER OXIDIZER FOR ALKALINE PERSULFATE OXIDATION TO DETERMINING TOTAL NITROGEN IN SOLUTION

Using Kjeldahl method to determinate the total N in solutions needs to concentrate and reduce the NO₃^--N and NO₂^--N to NH₄⁺-N. That is unconvenient.Recently,because of its convenience and rapid, the alkaline persulfate oxidation method(APOM)proposed by Koroleff was used to determine the total N in seawater and soil extracts. It is found that there is a close relationship between the oxidation efficiency and the composition of oxidizer, however, the composition of oxidazer used by researchers was various. Therefore, the object of this research was to choose a proper oxidzer for APOM.The concentraction of the oxidizer using to determine the total nitrogen in solution by alkaline persulfate oxidation showed that there was a close relationship between the pH of solution in oxidation reaction and the efficiency of oxidation.The concentration of persulfate and NaOH of the oxidizer was key for converting other form nitrogen into NO₃^--N. It was concluded that 3% persulfate combined with 0. 15 mol·L^-1 NaOH was a suitable oxidizer: its maximum limit of detecting urea-N was about 80mg. L^-1; and could recover the nitrogen of L-alanine and EDTA in solution quantitatively. Total nitrogen determined by alkaline persulfate was agreed with that by Kjeldahl method.