全自动定氮仪碱解蒸馏法测定植物营养液中硝态氮和铵态氮  

Determination of nitrate nitrogen and ammonium nitrogen in nutrient solution by alkali-hydrolyzed distillation method with automatic nitrogen analyzer

作　　者：高飞[1] 陈素贤 李昌伟[1] 刘瑜[1] 张春红 Gao Fei;Chen Suxian;Lin Changwei;Liu Yu;Zhang Chunhong(Beijing Soil Fertilizer Extension Service Station,Beijing 100029,China)

机构地区：[1]北京市土肥工作站,北京100029

出　　处：《化学分析计量》2021年第11期59-62,共4页Chemical Analysis And Meterage

摘　　要：建立凯氏定氮仪法测定植物营养液中铵态氮和硝态氮的方法。将10 mL植物营养液置于凯氏定氮管中,加入4.5 mol/L氢氧化钠溶液10 mL,利用锌-硫酸亚铁还原剂将营养液中硝态氮(NO_(3)^(-)-N)转化为铵态氮(NH_(4)^(+)-N),经蒸馏后被定量吸收在硼酸溶液中,用标准酸进行滴定,计算营养液中总氮含量;不加锌-硫酸亚铁还原剂时,测定营养液中的NH_(4)^(+)-N含量,采用差减法计算出营养液中NO_(3)^(-)-N含量。方法的检出限(以铵态氮计)为0.15 mg/L,硝态氮和铵态氮测定结果的相对标准偏差分别为1.23%~2.75%、0.83%~2.84%(n=5),加标回收率为98.7%~100.8%。该方法满足LY/T 1228—2015《森林土壤氮的测定》标准要求。The method of determination of nitrate nitrogen and ammonium nitrogen in nutrient solution with automatic nitrogen analyzer after alkali-hydrolyzed distillation was established.10 mL plant nutrient solution was put into a Kjeldahl tube,added 10 mL 4.5 mol/L sodium hydroxide solution,the nitrate nitrogen(NO_(3)^(-)N)in nutrient solution was converted into ammonium nitrogen(NH_(4)^(+)-N)with zinc-ferrous sulfate reducing agent,which was absorbed quantitatively in boric acid solution after distillation.The total nitrogen content in nutrient solution was calculated with standard acid titration.When no zinc-ferrous sulfate reducing agent was added,the content of NH_(4)^(+)-N in nutrient solution was determined,and the content of NO_(3)^(-)N in nutrient solution was calculated by difference subtraction method.The detection limit of the method was 0.15 mg/L(In terms of ammonium nitrogen).The relative standard deviations of determination results were 1.23%-2.75%and 0.83%-2.84%(n=5)for nitrate nitrogen and ammonium nitrogen,respectively,the recoveries ranged from 98.7%to 100.8%.The method meet the requirements of LY/T 1228-2015 Nitrogen Determination Methods of Forest Soils.

关 键 词：营养液 铵态氮 硝态氮 全自动定氮仪 

分 类 号：O657.1[理学—分析化学]