摘要
研究了碱提取吹扫捕集气相色谱冷原子荧光光谱法测定沉积物中甲基汞的影响因素,包括载气流速、柱温、衍生化试剂、样品称取量、前处理时碱性提取液加入量和反应瓶中提取液加入量的影响,分析了提取液加入量对Tenax管的影响、提取液保存的影响因素、沉积物样品保存的影响因素以及样品中Hg^(2+)的干扰影响。根据影响情况确定最佳测定条件,应用于广西龙江河流域上9个代表性监测断面的底泥样品中甲基汞的测定,采用污染指数法对该流域甲基汞的污染现状进行评价。结果表明,最佳载气流速范围为22~27 mL/min,最佳柱温为46℃。衍生化试剂选择四乙基硼化钠和四丙基硼化钠均能达到较好的回收率。样品称取量选择0.50 g时回收率好。前处理时碱性提取液的加入量对甲基汞的提取效率没有显著影响。为保证水相衍生反应体系最终pH在5左右,乙酸-乙酸钠缓冲溶液的加入量随提取液加入量的增加而增加。当缓冲溶液为300μL时,提取液小于150μL不会影响Tenax管性能。避光与否对提取液的保存和样品的保存影响都不大,提取液保存3 d后、样品保存15 d后,甲基汞回收率将低于80%。衍生化前定量体积提取液中Hg^(2+)含量与甲基汞浓度呈现正相关性。广西龙江河流域上9个断面的甲基汞污染等级及平均值浓度污染等级都显示为中度污染。
The influencing factors in the determination of methylmercury in sediments by purge and trap/gas chromatography cold vapor atomic fluorescence spectrometry were studied,including carrier gas flow rate,column temperature,derivative reagent,sample quantity,the amount of alkaline extraction solution and the amount of extraction solution in the reaction bottle.Analyzed the influence of the amount of extraction solution on Tenax tube,the influencing factors in the preservation of the extraction solution,the influencing factors in the preservation of sediment samples and the interference effect of Hg^(2+) in samples.Based on the results of the study to determine the optimal determination conditions.The optimal determination conditions were applied to the determination of methylmercury in sediments from 9 representative cross sections on the Longjiang River in Guangxi.The pollution index method was used to evaluate the pollution degree of methylmercury.The experimental results show that the optimal carrier gas flow rate range is 22-27 mL/min and the optimal column temperature is 46 ℃.High recovery rates can be achieved by using sodium tetraethyl boride or sodium(tetra-n-propyl) borate as derivatization reagents.When the sample weight is 0.50 g,the recovery rate is high.The amount of alkaline extraction solution had no significant effect on the extraction efficiency of methylmercury.In order to ensure that the final pH value of the aqueous phase derivative reaction system is around 5,the amount of acetic acid-sodium acetate buffer solution should increase with the amount of the extraction solution.When the buffer solution is 300 μL and the extraction solution is less than 150 μL,the performance of Tenax tube is not affected.There is little influence on the preservation of extraction solution and sample when stored away from light.The recovery rate of methylmercury was lower than 80% when the storage time of the extraction solution was more than 3 days and the sample was more than 15 days.Before derivatization,the con
作者
龙雯琪
许秀艳
常诚
毕军平
刘沛
余涛
朱瑞瑞
张霖琳
LONG Wenqi;XU Xiuyan;CHANG Cheng;BI Junping;LIU Pei;YU Tao;ZHU Ruirui;ZHANG Linlin(Hunan Ecological and Environmental Monitoring Center,State Environmental Protection Key Laboratory of Monitoring for Heavy Metal Pollutants,Changsha 410019,China;China National Environmental Monitoring Centre,State Environmental Protection Key Laboratory of Quality Control in Environmental Monitoring,Beijing 100012,China;BCEG Environmental Remediation Co.,LTD,Beijing 100015,China)
出处
《中国环境监测》
CAS
CSCD
北大核心
2023年第2期169-176,共8页
Environmental Monitoring in China
基金
国家生态环境保护标准项目(2016-29)
首都科技条件平台科研项目(Z181100009518003)
湖湘高层次人才聚集工程-创新团队项目(2021RC5030)。
