HJ6342012土壤氨氮亚硝酸盐氮硝酸盐氮的测定氯化钾溶液提取分光光度法

中华人民共和国国家环境保护标准HJ634—2012土壤氨氮、亚硝酸盐氮、硝酸盐氮的测定氯化钾溶液提取-分光光度法Soil-Determinationofammonium,nitriteandnitratebyextractionwithpotassiumchloridesolution-spectrophotometricmethods（发布稿）本电子版为发布稿。请以中国环境科学出版社出版的正式标准文本为准。2012-02-29发布2012-06-01实施环境保护部发布I目次前言···········································································································································II1适用范围·······························································································································12规范性引用文件···················································································································13方法原理·······························································································································14试剂和材料···························································································································15仪器和设备···························································································································46样品·······································································································································57分析步骤·······························································································································58结果计算与表示···················································································································79精密度和准确度···················································································································810质量保证和质量控制········································································································9附录A（资料性附录）本标准与ISO/TS14256-1:2003（E）的章条编号对照·····················10附录B（资料性附录）本标准与ISO/TS14256-1:2003（E）的技术性差异及其原因·········12附录C（资料性附录）还原柱的制备······················································································13II前言为贯彻《中华人民共和国环境保护法》，保护环境，保障人体健康，规范土壤中氨氮、亚硝酸盐氮、硝酸盐氮的测定方法，制订本标准。本标准规定了测定土壤中氨氮、亚硝酸盐氮、硝酸盐氮的氯化钾溶液提取－分光光度法。本标准的技术内容为修改采用《土壤质量硝酸盐氮、亚硝酸盐氮、氨氮的测定氯化钾溶液提取法》（ISO/TS14256-1:2003（E））。附录A给出了本标准与ISO/TS14256-1:2003（E）章条编号对照一览表，附录B给出了本标准与ISO/TS14256-1:2003（E）的技术性差异及其原因。本标准为首次发布。本标准附录A~附录C为资料性附录。本标准由环境保护部科技标准司组织制订。本标准主要起草单位：鞍山市环境监测中心站。本标准环境保护部2012年2月29日批准。本标准自2012年6月1日起实施。本标准由环境保护部解释。1土壤氨氮、亚硝酸盐氮、硝酸盐氮的测定氯化钾溶液提取-分光光度法1适用范围本标准规定了测定土壤中氨氮、亚硝酸盐氮、硝酸盐氮的氯化钾溶液提取－分光光度法。本标准适用于土壤中氨氮、亚硝酸盐氮、硝酸盐氮的测定。当样品量为40.0g时，本方法测定土壤中氨氮、亚硝酸盐氮、硝酸盐氮的检出限分别为0.10mg/kg、0.15mg/kg、0.25mg/kg，测定下限分别0.40mg/kg、0.60mg/kg、1.00mg/kg。2规范性引用文件本标准内容引用了下列文件中的条款。凡是不注日期的引用文件，其有效版本适用于本标准HJ168环境监测分析方法标准制修订技术导则HJ613土壤干物质和水分的测定重量法HJ/T166土壤环境监测技术规范ISO/TS14256-1土壤质量硝酸盐氮、亚硝酸盐氮、氨氮的测定氯化钾溶液提取法（Soilquality-Determinationofnitrate,nitriteandammoniuminfield-moistsoilsbyextractionwithpotassiumchloridesolution）3方法原理3.1氨氮氯化钾溶液提取土壤中的氨氮，在碱性条件下，提取液中的氨离子在有次氯酸根离子存在时与苯酚反应生成蓝色靛酚染料，在630nm波长具有昀大吸收。在一定浓度范围内，氨氮浓度与吸光度值符合朗伯-比尔定律。3.2亚硝酸盐氮氯化钾溶液提取土壤中的亚硝酸盐氮，在酸性条件下，提取液中的亚硝酸盐氮与磺胺反应生成重氮盐，再与盐酸N-（1-萘基）-乙二胺偶联生成红色染料，在波长543nm波长具有昀大吸收。在一定浓度范围内，亚硝酸盐氮浓度与吸光度值符合朗伯-比尔定律。3.3硝酸盐氮氯化钾溶液提取土壤中的硝酸盐氮和亚硝酸盐氮，提取液通过还原柱，将硝酸盐氮还原为亚硝酸盐氮，在酸性条件下，亚硝酸盐氮与磺胺反应生成重氮盐，再与盐酸N-（1-萘基）-乙二胺偶联生成红色染料，在波长543nm处具有昀大吸收，测定硝酸盐氮和亚硝酸盐氮总量。硝酸盐氮和亚硝酸盐氮总量与亚硝酸盐氮含量之差即为硝酸盐氮含量。4试剂和材料2除非另有注明，分析时均使用符合国家标准的分析纯试剂，实验用水为电导率小于0.2mS/m（25℃时测定）的去离子水。4.1氨氮4.1.1浓硫酸：ρ（H2SO4）=1.84g/ml。4.1.2二水柠檬酸钠（C6H5Na3O7·2H2O）。4.1.3氢氧化钠（NaOH）。4.1.4二氯异氰尿酸钠（C3Cl2N3NaO3·H2O）。4.1.5氯化钾（KCl）：优级纯。4.1.6氯化铵（NH4Cl）：优级纯于105℃下烘干2h。4.1.7氯化钾溶液：c（KCl）=1mol/L称取74.55g氯化钾（4.1.5），用适量水溶解，移入1000ml容量瓶中，用水定容，混匀。4.1.8氯化铵标准贮备液：ρ（NH4Cl）=200mg/L称取0.764g氯化铵（4.1.6），用适量水溶解，加入0.30ml浓硫酸（4.1.1），冷却后，移入1000ml容量瓶中，用水定容，混匀。该溶液在避光、4℃下可保存一个月。或直接购买市售有证标准溶液。4.1.9氯化铵标准使用液：ρ（NH4Cl）=10.0mg/L量取5.0ml氯化铵标准贮备液（4.1.8）于100ml容量瓶中，用水定容，混匀。用时现配。4.1.10苯酚溶液称取70g苯酚（C6H5OH）溶于1000ml水中。该溶液贮存于棕色玻璃瓶中，在室温条件下可保存一年。注：配制苯酚溶液时应避免接触皮肤和衣物。4.1.11二水硝普酸钠溶液称取0.8g二水硝普酸钠{Na2[Fe（CN）5NO]·2H2O}溶于1000ml水中。该溶液贮存于棕色玻璃瓶中，在室温条件下可保存三个月。4.1.12缓冲溶液称取280g二水柠檬酸钠（4.1.2）及22.0g氢氧化钠（4.1.3），溶于500ml水中，移入1000ml容量瓶中，用水定容，混匀。4.1.13硝普酸钠-苯酚显色剂量取15ml二水硝普酸钠溶液（4.1.11）及15ml苯酚溶液（4.1.10）和750ml水，混匀。该溶液用时现配。4.1.14二氯异氰尿酸钠显色剂称取5.0g二氯异氰尿酸钠（4.1.4）溶于1000ml缓冲溶液（4.1.12）中，4℃下可保存一个月。4.2亚硝酸盐氮4.2.1浓磷酸：ρ（H3PO4）=1.71g/ml。34.2.2氯化钾（KCl）：优级纯。4.2.3亚硝酸钠（NaNO2）：优级纯干燥器中干燥24h。4.2.4氯化钾溶液：c（KCl）=1mol/L同4.1.7。4.2.5亚硝酸盐氮标准贮备液：ρ（NO2-N）=1000mg/L称取4.926g亚硝酸钠（4.2.3），用适量水溶解，移入1000ml容量瓶中，用水定容，混匀。该溶液贮存于聚乙烯塑料瓶中，4℃下可保存六个月。或直接购买市售有证标准溶液。4.2.6亚硝酸盐氮标准使用液Ⅰ：ρ（NO2-N）=100mg/L量取10.0ml亚硝酸盐氮标准贮备液（4.2.5）于100ml容量瓶中，用水定容，混匀。用时现配。4.2.7亚硝酸盐氮标准使用液Ⅱ：ρ（NO2-N）=10.0mg/L量取10.0ml亚硝酸盐氮标准使用液Ⅰ（4.2.6）于100ml容量瓶中，用水定容，混匀。用时现配。4.2.8磺胺溶液（C6H8N2O2S）向1000ml容量瓶中加入600ml水，再加入200ml浓磷酸（4.2.1），然后加入80g磺胺。用水定容，混匀。该溶液于4℃下可保存一年。4.2.9盐酸N-（1-萘基）-乙二胺溶液称取0.40g盐酸N-（1-萘基）-乙二胺（C12H14N2·2HCl）溶于100ml水中。4℃下保存，当溶液颜色变深时应停止使用。4.2.10显色剂分别量取20ml磺胺溶液（4.2.8）、20ml盐酸N-（1-萘基）-乙二胺溶液（4.2.9）、20ml浓磷酸（4.2.1）于100ml棕色试剂瓶中，混合。4℃下保存，当溶液变黑时应停止使用。4.3硝酸盐氮4.3.1浓磷酸：ρ（H3PO4）=1.71g/ml。4.3.2浓盐酸：ρ（HCl）=1.12g/ml。4.3.3镉粉：粒径0.3mm~0.8mm。4.3.4氯化钾（KCl）：优级纯。4.3.5硝酸钠（NaNO3）：优级纯干燥器中干燥24h。4.3.6亚硝酸钠（NaNO2）：优级纯同4.2.3。4.3.7氯化铵（NH4Cl）。4.3.8硫酸铜（CuSO4.5H2O）。4.3.9氨水（NH4OH）：优级纯。4.3.10氯化钾溶液：c（KCl）=1mol/L同4.1.7。4.3.11硝酸盐氮标准贮备液：ρ（NO3-N）=1000mg/L4称取6.068g硝酸钠（4.3.5），用适量水溶解，移入1000