Acidimetric Determination of NH4+-Nitrogen in Compound Fertilizers After Separation by Cold-Air Distillation
摘 要
提出了用冷空气蒸馏分离酸滴定法在多种形态氮共存时测定复合肥料中铵态氮含量的方法。取适量复合肥料样品于蒸馏瓶中,与550 g·L-1碳酸钾溶液60 mL反应,溶液总体积以不宜超过110 mL。通过空气在流量为3 L·min-1和不加热条件下蒸馏8 h,生成的氨馏出并先后吸收于相互连接的3个吸收瓶中,每一吸收瓶中预置硼酸吸收溶液50 mL,用0.05 mol·L-1盐酸标准溶液滴定3溶液至指示剂呈暗红色,记录所耗盐酸标准溶液的总量。将吸收瓶重新按装在蒸馏系统中继续蒸馏1 h后再进行滴定,以所耗盐酸标准溶液量不超过0.03 mL认为测定完成。根据滴定所耗盐酸标准溶液的总量计算样品中铵态氮的含量。根据3个样品各5次测定结果计算,得到方法的回收率在99.7%~100.1%之间,相对标准偏差在0.12%~0.55%之间。
Abstract
Ammonium nitrogen in compound fertilizers in the presence of nitrogen in various species was determined by acidimentry with 0.05 mol·L-1 HCl standard solution after separation by cold distillation. Appropriate amount of the sample was reacted with 60 mL of 550 g·L-1 K2CO3 solution in a distillation flask, to form gaseous NH3 which was carried over by cold air with flow-rate of 3 L·min-1 and absorbed in 3 portions of 50 mL of boric acid solution previously added into 3 separate absorption flasks conrected in series, during the course of 8 h. The solutions in the 3 flasks were titrated with HCl standard solution to a dark red color of the indicator. The cold distillation was carried on again for another one hour. The distillates were titrated again and if the consumption of HCl standard solution was less than 0.03 mL, the determination was concluded and content of NH4+-nitrogen was calculated on the base of the total volume of standard HCl solution consumed in the titration. From the results of 5 determinations each in analysis of 3 samples by the present method, values of recovery were found in the range of 99.7% to 100.1% with RSD′s (n=5) ranged from 0.12% to 0.55%.
中图分类号 O655.22
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收稿日期 2011/5/13
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备注王素梅(1978-),女,山东郓城人,工程师,硕士,主要从事煤焦化工方面的研究。
引用该论文: WANG Su-mei,LI Quan-bin,HOU Ying-tao. Acidimetric Determination of NH4+-Nitrogen in Compound Fertilizers After Separation by Cold-Air Distillation[J]. Physical Testing and Chemical Analysis part B:Chemical Analysis, 2011, 47(11): 1274~1277
王素梅,李权斌,侯英涛. 冷空气蒸馏分离酸滴定法测定复合肥中铵态氮[J]. 理化检验-化学分册, 2011, 47(11): 1274~1277
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参考文献
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【2】孙又宁.半自动定氮仪测定肥料中总氮含量的研究[J].中国土壤与肥料, 2008,4:69-72.
【3】陈红军.肥料中各种形态氮的测定方法[J].精细化工中间体, 2004,35(3):59-61.
【4】车弟强,杜舜贤.分光光度法测定复混肥料中硝态氮含量[J].磷肥与复肥, 2007,22(6):65-65.
【5】闫力.复混肥料中酰胺态氮和铵态氮测定方法的探讨[J].磷肥与复肥, 2003,18(6):63-63.
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