在线镉柱还原-连续流动注射法测定地表水和海水中硝酸盐氮
|
摘要
硝酸盐氮经镉柱还原为亚硝酸盐氮,亚硝酸盐氮在中性条件下与酸性显色剂(磺胺-盐酸萘乙二胺)反应生成玫红色的重氮-偶合物,在波长550nm处测量其吸光度,其吸光度与硝酸盐氮和亚硝酸盐氮质量浓度的和在3.00mg·L~(-1)以内呈线性关系。据此原理采用连续流动注射法测定地表水和海水中硝酸盐氮的含量,每小时可测定60个样品。选用pH 7.50±0.05的0.075mol·L~(-1)咪唑缓冲溶液作为缓冲剂,所用镉柱为由粒径0.3～0.8mm的镉粒填装的有效长度为10cm的镉圈,使用前须按如下顺序激活(于2mol·L~(-1)盐酸溶液中1min,放入0.005mol·L~(-1)硫酸铜激活溶液中2 min,再放入2 mol·L~(-1)盐酸溶液中5 min)。方法的检出限(3s)为0.000 1mg·L~(-1),方法用于两种标准物质的分析,测定值与认定值相符。方法用于水样的分析,并进行加标回收试验,测得回收率在99.0%～102%之间,测定值的相对标准偏差(n=6)小于2.5%。
Nitrate nitrogen can be reduced to nitrite nitrogen by cadmium column,and nitrite nitrogen produced can react with a acidic color reagent composed of sulfanilamide and N-(1-naphthyl)-ethylene diamine in neutral medium to form a rose-red colored diazo compound having its absorption maximum at 550 nm.Linear relationship between values of absorbane of the colored diazo compound and the sum of mass concentration of nitrate nitrogen and nitrite nitrogen was found within 3.00 mg·L~(-1).Base on this phenomenon,continuous flow injection method was applied to the determination of nitrate nitrogen in surface water and seawater.Sixty samples could be analyzed in an hour.Imidazole solution(0.075 mol·L~(-1),pH 7.50±0.05)was used as buffer in the determination.Granular cadmium with granularity of 0.3 to 0.8 mm packed in a coil tubing to an effective length of 10 cm was used as cadmium column,and it should be activated in the following manner before use:dipping successively in 2 mol·L~(-1) HCl solution for 1 min,in 0.005 mol·L~(-1) CuSO_4 solution for 2 min and in 2 mol·L~(-1) HCl solution again for5 min.Detection limit(3 s)of the method found was 0.000 1 mg·L~(-1).Two CRMs were analyzed by the method,giving results in consistency with the certified values.Water samples were analyzed by the method and used as matrixes for recovery by standard addition method,the results obtained were in the range of 99.0%~(-1)02%,and values of RSDs(n=6)found were less than 2.5%.
Nitrate nitrogen can be reduced to nitrite nitrogen by cadmium column,and nitrite nitrogen produced can react with a acidic color reagent composed of sulfanilamide and N-(1-naphthyl)-ethylene diamine in neutral medium to form a rose-red colored diazo compound having its absorption maximum at 550 nm.Linear relationship between values of absorbane of the colored diazo compound and the sum of mass concentration of nitrate nitrogen and nitrite nitrogen was found within 3.00 mg·L~(-1).Base on this phenomenon,continuous flow injection method was applied to the determination of nitrate nitrogen in surface water and seawater.Sixty samples could be analyzed in an hour.Imidazole solution(0.075 mol·L~(-1),pH 7.50±0.05)was used as buffer in the determination.Granular cadmium with granularity of 0.3 to 0.8 mm packed in a coil tubing to an effective length of 10 cm was used as cadmium column,and it should be activated in the following manner before use:dipping successively in 2 mol·L~(-1) HCl solution for 1 min,in 0.005 mol·L~(-1) CuSO_4 solution for 2 min and in 2 mol·L~(-1) HCl solution again for5 min.Detection limit(3 s)of the method found was 0.000 1 mg·L~(-1).Two CRMs were analyzed by the method,giving results in consistency with the certified values.Water samples were analyzed by the method and used as matrixes for recovery by standard addition method,the results obtained were in the range of 99.0%~(-1)02%,and values of RSDs(n=6)found were less than 2.5%.
引文
[1]陈水土,戴民汉,苏国成,等.海水中硝酸盐铜镉柱还原测定操作步骤的优化研究[J].台湾海峡,2004,23(4):429-435.
[2]《水和废水监测分析方法》编委会.水和废水监测分析方法[M].4版.北京:中国环境科学出版社,2002.
[3]HJ/T 346-2007水质硝酸盐氮的测定紫外分光光度法(试行)[S].
[4]吴昊,江敏.紫外二次曲线法测定硝酸盐氮方法探讨[J].环境科学与技术,2008,31(1):65-68.
[5]GB 17378.4-2007海洋监测规范第4部分:海水分析[S].
[6]林红梅,林奇,张远辉,等.在线样品前处理大体积进样离子色谱法直接测定海水中亚硝酸盐、硝酸盐和磷酸盐[J].色谱,2012,30(4):374-377.
[7]韩耀宗.基于离子色谱法的水样中硝酸盐氮和亚硝酸盐氮含量测定[J].安徽农业科学,2010,38(3):1385-1389.
[8]魏福祥,傅晓文,马晓珍.镉柱还原光度法测定海水中的硝酸盐氮[J].分析试验室,2011,30(7):10-13.
[9]孙西艳,洪陵成,叶宏萌.在线镉柱还原-流动注射法测定水样中硝酸盐氮实验[J].水资源保护,2010,26(5):75-77.
[10]韩彬,曹磊,郑立,等.夹管电磁阀定量-流动注射分析系统测定海水中亚硝酸盐和硝酸盐氮[J].分析化学,2010,38(12):1832-1837.
[11]孙西艳,洪陵成,笪海文,等.双流路互不干扰流动注射在线同时测定水中硝酸盐氮和亚硝酸盐氮[J].化学分析计量,2009,18(5):30-33.
[12]赵萍,陈金辉,肖靖泽.在线镉柱还原-流动注射分析法测定水中硝酸盐/亚硝酸盐氮[J].生命科学仪器,2007,5(6):19-22.
[13]LPEZ PASQUALI C E,FERNNDEZ HERNAN-DO P,DURAND ALEGRIA J S.Spectrophotometric simultaneous determination of nitrite,nitrate and ammonium in soils by flow injection analysis[J].Analytica Chimica Acta,2007,600(1/2):177-182.
[14]陈灿云,张志军,梁高亮,等.连续流动分析仪测定环境水样中硝酸盐氮和亚硝酸盐氮[J].理化检验-化学分册,2004,40(10):613-614.
[2]《水和废水监测分析方法》编委会.水和废水监测分析方法[M].4版.北京:中国环境科学出版社,2002.
[3]HJ/T 346-2007水质硝酸盐氮的测定紫外分光光度法(试行)[S].
[4]吴昊,江敏.紫外二次曲线法测定硝酸盐氮方法探讨[J].环境科学与技术,2008,31(1):65-68.
[5]GB 17378.4-2007海洋监测规范第4部分:海水分析[S].
[6]林红梅,林奇,张远辉,等.在线样品前处理大体积进样离子色谱法直接测定海水中亚硝酸盐、硝酸盐和磷酸盐[J].色谱,2012,30(4):374-377.
[7]韩耀宗.基于离子色谱法的水样中硝酸盐氮和亚硝酸盐氮含量测定[J].安徽农业科学,2010,38(3):1385-1389.
[8]魏福祥,傅晓文,马晓珍.镉柱还原光度法测定海水中的硝酸盐氮[J].分析试验室,2011,30(7):10-13.
[9]孙西艳,洪陵成,叶宏萌.在线镉柱还原-流动注射法测定水样中硝酸盐氮实验[J].水资源保护,2010,26(5):75-77.
[10]韩彬,曹磊,郑立,等.夹管电磁阀定量-流动注射分析系统测定海水中亚硝酸盐和硝酸盐氮[J].分析化学,2010,38(12):1832-1837.
[11]孙西艳,洪陵成,笪海文,等.双流路互不干扰流动注射在线同时测定水中硝酸盐氮和亚硝酸盐氮[J].化学分析计量,2009,18(5):30-33.
[12]赵萍,陈金辉,肖靖泽.在线镉柱还原-流动注射分析法测定水中硝酸盐/亚硝酸盐氮[J].生命科学仪器,2007,5(6):19-22.
[13]LPEZ PASQUALI C E,FERNNDEZ HERNAN-DO P,DURAND ALEGRIA J S.Spectrophotometric simultaneous determination of nitrite,nitrate and ammonium in soils by flow injection analysis[J].Analytica Chimica Acta,2007,600(1/2):177-182.
[14]陈灿云,张志军,梁高亮,等.连续流动分析仪测定环境水样中硝酸盐氮和亚硝酸盐氮[J].理化检验-化学分册,2004,40(10):613-614.