中文摘要：

本研究比较了鲁如坤法、国标法、Doyle法3种基于过硫酸钾氧化法测定可溶性有机氮的前处理方法，使用开氏蒸馏和同位素质谱法分别测定不同方法处理后样品的全氮和^15N回收率，以比较获得最优的前处理方法。结果表明，Doyle法测得的标准溶液全氮和^15N回收率均高于鲁如坤法、国标法。因此，本研究推荐使用过硫酸钾氧化法测定可溶性有机氮含量和^15N丰度时，氧化剂的前处理方法为高压120℃，消煮时间1h，氧化剂50g／LK2S208，16．8g／LNaOH，30g／LH3804，浸提液与氧化剂比例为1：1。

英文摘要：

In the study three methods ofpersulfate digestion for dissolved organic nitrogen （DON） analysis were compared. The recoveries were calculated by using kjeldahl method for the total dissolved nitrogen （TDN） and isotope ratio mass spectrometry （IRMS） for ^15N. The results showed that the Doyle methods obtained higher recovery. Therefore the pre-treatment method of analysis of DON was recommend at the condition of the volume ratio of oxidizing reagent （50 g/L K2S208, 16.8 g/L NaOH, 30 g/L H3BO4） to extracts was 1 ： 1 and the digest is performed at temperature 120℃ for one hour.