尿素氮测定方法的探讨

Discuss the Determination of Urea Nitrogen

通过实验，将 H G/T 4137-2010中测脲甲醛缓释肥中游离尿素氮含量测定条件，40℃水浴恒温反应时间，可由30 min缩短为5 min；或于室温（25～30℃）下反应15 min；1％脲酶溶液用量由25 ml减少为8 ml。改进后的方法回收率在98.6％～99.5％之间，相对标准偏差RSD≤1.5％，精密度和准确度较改进前有所提高，可满足工业生产控制及分析检测要求，达到准确、快速、节约、简便易行的目的。

After the experiment , the method （ HG/T4137 -2010） of determining the free urea nitrogen content in urea-formaldehyde slow-release fertilizer is improved , and the measures are as follows ：the time of 30min for 40 ℃ water bath thermostatic reaction could be shorten to 5min;or the reaction time could be 15 min at room temperature （ 25~30 ℃） ;25 ml of 1% urease solution dosage is reduced to 8 ml. After improvement , the recovery rate is at 98.6% ~99.5% , RSD≤1 .5% , also the precision and accuracy are improved. T his method could meet industrial production control and analytical determination requirements , and it is accurate , rapid , economical and simple .