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汞是环境中毒性最强的重金属元素之一[1]. 它具有持久性、长距离迁移性和生物富集性,在自然界中能转化成剧毒的甲基汞,并通过食物链高度富集和放大,不仅对生态环境会产生严重危害,还时刻威胁着人类健康[2-3]. 2017年8月,旨在全球范围内控制和减少汞排放的《关于汞的水俣公约》正式生效,标志着全球携手减少汞污染迈出了关键一步. 我国长期以来被认为是汞生产、使用和排放最大的国家,因而面临巨大的履约压力[4]. 控制汞污染和汞排放,不仅要有完善的制度法规,还需要有准确的汞检测分析技术[5]. 海水中总汞含量低、测定过程中容易引入外源污染物且高盐基体可导致光谱干扰[6],稳定和精确测定海水中痕量总汞一直是环境监测领域亟待解决的难点之一[7].
目前测定水中总汞的国家和行业标准方法主要有冷原子吸收法、分光光度法和(冷)原子荧光法. 冷原子吸收法具有重现性好、灵敏度高等优点,但由于原子吸收光谱的限制,该方法线性范围较窄,对于海水中痕量总汞的测定,检出限并不理想[8];分光光度法一般采取双硫腙分光光度法,该方法灵敏度低,检出限高、并且操作复杂,现已较少使用[9];原子荧光测定总汞,优点在于灵敏度高、线性范围宽,但敞开式的直接液体进样方式容易导致样品的沾污、管路吸附导致汞的记忆效应明显、而且无法直接测定海水中痕量总汞[10].
本研究建立的方法是基于冷原子荧光光谱法,前端增加吹扫捕集装置,通过全封闭式顶空进样方式直接进入气态样品,避免样品沾污,同时实现汞与高盐基体的分离;利用对汞无吸附的特氟龙材质管路,降低汞的记忆效应;通过两级金捕获器进行金汞齐反应,实现汞的富集,从而显著降低方法检出限,提升灵敏度. 本研究开展了条件优化实验,确定了氧化效率最高且操作简洁的消解体系、最佳的还原剂用量和还原时效等重要参数. 在上述工作的基础上,对优化后的方法进行验证,获得了方法的检出限、测定下限、精密度、准确度等,特别是利用不同海区的多种海水样品对该方法的适用性进行验证,并与现行国标仲裁方法进行比较,以期得到一种稳定、精确测定海水中痕量总汞的方法.
基于氧化/吹扫捕集-冷原子荧光光谱法测定海水中痕量总汞
Determination of trace total mercury in seawater by oxidation/purge and trap-cold atomic fluorescence spectrometry
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摘要: 基于氧化/吹扫捕集-冷原子荧光光谱法,建立了准确测定海水中痕量总汞的方法. 采用硫酸和过硫酸钾体系氧化海水样品,盐酸羟胺预还原,再经氯化亚锡将全部的汞离子还原为单质汞,原位吹扫和金汞齐捕集,在波长253.7 nm处原子荧光光谱法分析测定. 结果表明:该方法回收率为94%—104%,精密度相对标准偏差为2.1%—3.6%,方法检出限为0.1 ng·L−1,测定下限为0.4 ng·L−1,与现行国标方法相比,该方法增加了原位吹扫捕集的前处理步骤,因而灵敏度更高,检出限更低,也具有很好的稳定性. 用不同海区实际海水样品进行验证,结果显示,该方法满足实际样品的分析需求,建议在海水水质的汞监测领域能够拓展应用.
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关键词:
- 吹扫捕集-冷原子荧光光谱法 /
- 海水 /
- 痕量总汞 /
- 痕量总汞分析仪.
Abstract: Based on the oxidation/purge and trap-cold atomic fluorescence spectrometry, a method for the accurate determination of trace total mercury in seawater was developed in this paper. The seawater sample was oxidized by sulfuric acid and potassium persulfate system, pre-reduced by hydroxylamine hydrochloride, and then reduced to elemental mercury by stannous chloride. The mercury ion was purged in the same position and trapped by gold amalgam. It was analyzed and determined by atomic fluorescence spectrometry at the wavelength of 253.7 nm. The results showed that the recovery was 94%—104%, the relative standard deviation of precision was 2.1%—3.6%, the detection limit was 0.1 ng·L−1, and the lower limit of determination was 0.4 ng·L−1. Compared with the current national standard method, the developed method has higher sensitivity, lower detection limit, and better stability. The method was validated by actual seawater samples from different sea areas, and the results showed that the method meets the analysis requirements of actual samples. Therefore, it is expected that the method can be widely used in the mercury determination of sea water. -
表 1 准确度结果
Table 1. Results of the accuracy
加标浓度/(ng·L−1)
Spiked concentration检测浓度/(ng·L−1)
Detection concentration平均值/(ng·L−1)
Average value回收率/%
Recovery1 2 3 4 15.0 20.6 20.4 21.2 21.3 20.9 104 35.0 41.1 39.7 42.8 39.3 40.7 101 55.0 54.0 57.2 55.9 60.4 56.9 94 注:本底浓度为5.30 ng·L−1 表 2 精密度结果
Table 2. Results of the precision
加入量/pg
Amount added测量值/pg
Detection value平均值/pg
Average value相对标准偏差/%
RSD1 2 3 4 5 6 7 100 93.2 98.4 102 101 104 97.5 104 99.9 3.6 500 485 477 491 488 498 519 501 494 2.6 1000 965 924 930 956 906 944 914 935 2.1 表 3 测定不同海区实际样品的结果
Table 3. Results of determination of actual samples from different sea areas
检测浓度/(ng·L−1)
Detection concentration平均值/(ng·L−1)
Average value标准偏差/(ng·L−1)
Standard deviation相对标准
偏差/%RSD1 2 3 4 5 6 1#样品 6.01 6.61 6.80 7.09 7.47 7.14 6.85 0.51 7.4 2#样品 3.88 3.85 3.95 3.16 3.57 3.10 3.59 0.38 10 3#样品 18.7 21.2 20.9 20.0 20.7 20.6 20.4 0.90 4.4 4#样品 10.6 10.5 10.7 10.1 10.9 10.5 10.6 0.27 2.5 表 4 实际样品与标准样品测定结果的对比
Table 4. Comparison of determination results between actual samples and standard samples
序号
Number实际样品测定/(ng·L−1)
Determination of actual samples标准样品测定/(μg·L−1)
Determination of standard samples本研究方法
The present method国标方法
The national standard method本研究方法
The present method国标方法
The national standard method1 6.01 ND 16.6 17.4 2 6.61 ND 16.7 16.9 3 6.80 ND 17.2 17.5 4 7.09 ND 16.7 16.0 5 7.47 ND 16.4 16.7 6 7.14 ND 16.4 16.4 平均值 6.85 — 16.7 16.8 相对标准偏差/% 0.51 — 1.7 3.6 注:ND为未检出;本研究方法为优化后的吹扫捕集-冷原子荧光光谱法;国标方法:《海洋监测规范》(GB17378.4—2007)中原子荧光法测定海水中汞的方法.
Note:ND represents No Detection; the present method is the optimized purge and trap-cold atomic fluorescence spectrometry; the national standard method is the atomic fluorescence spectrometry used to determine the mercury in sea water prescribed by “the Specification for Marine Monitoring” (GB17378.4-2007). -
[1] 王晓晨, 李天鹏, 尤凯鸿, 等. 汞的多介质环境行为研究进展 [J]. 环境科学与技术, 2018, 41(12): 90-97. doi: 10.19672/j.cnki.1003-6504.2018.12.014 WANG X C, LI T P, YOU K H, et al. The progress in the research on multimedium environmental behaviors of mercury [J]. Environmental Science & Technology, 2018, 41(12): 90-97(in Chinese). doi: 10.19672/j.cnki.1003-6504.2018.12.014
[2] 陈亮, 李述贤, 杜譞, 等. 《关于汞的水俣公约》履约困境和出路 [J]. 中国生态文明, 2015(2): 74-79. CHEN L, LI S X, DU X, et al. Difficulties and solutions for“the Minamata Convention on Mercury” [J]. China Ecological Civilization, 2015(2): 74-79(in Chinese).
[3] 孟其义, 钱晓莉, 陈淼, 等. 稻田生态系统汞的生物地球化学研究进展 [J]. 生态学杂志, 2018, 37(5): 1556-1573. doi: 10.13292/j.1000-4890.201805.024 MENG Q Y, QIAN X L, CHEN M, et al. Biogeochemical cycle of mercury in rice paddy ecosystem: A critical review [J]. Chinese Journal of Ecology, 2018, 37(5): 1556-1573(in Chinese). doi: 10.13292/j.1000-4890.201805.024
[4] 郭卫广, 刘建国. 全球汞控制公约形势及中国履约需求分析 [J]. 环境污染与防治, 2010, 32(9): 107-111. doi: 10.3969/j.issn.1001-3865.2010.09.026 GUO W G, LIU J G. Perspective of global mercury control convention and obligation analysis for China [J]. Environmental Pollution & Control, 2010, 32(9): 107-111(in Chinese). doi: 10.3969/j.issn.1001-3865.2010.09.026
[5] 孙阳昭, 陈扬, 蓝虹, 等. 中国汞污染的来源、成因及控制技术路径分析 [J]. 环境化学, 2013, 32(6): 937-942. doi: 10.7524/j.issn.0254-6108.2013.06.003 SUN Y Z, CHEN Y, LAN H, et al. Study on pollution sources, cause of mercury pollution and its control technical roadmap in China [J]. Environmental Chemistry, 2013, 32(6): 937-942(in Chinese). doi: 10.7524/j.issn.0254-6108.2013.06.003
[6] 阎海鱼, 冯新斌, 商立海, 等. 天然水体中痕量汞的形态分析方法研究 [J]. 分析测试学报, 2003, 22(5): 10-13. doi: 10.3969/j.issn.1004-4957.2003.05.003 YAN H Y, FENG X B, SHANG L H, et al. Speciation analysis of ultra trace levels of mercury in natural waters [J]. Journal of Instrumental Analysis, 2003, 22(5): 10-13(in Chinese). doi: 10.3969/j.issn.1004-4957.2003.05.003
[7] 刘莹, 翟世奎, 张爱滨, 等. ICP-MS测定海水中溶解态痕量重金属-直接稀释法 [J]. 海洋学报, 2008, 30(5): 151-158. LIU Y, ZHAI S K, ZHANG A B, et al. Determination of dissolved heavy trace metals in seawater on ICP-MS-Direct dilution method [J]. Acta Oceanologica Sinica, 2008, 30(5): 151-158(in Chinese).
[8] 韦利杭. 冷原子荧光光度法测定海水中的超痕量汞 [J]. 分析化学, 1996, 24(2): 247. doi: 10.3321/j.issn:0253-3820.1996.02.003 WEI L H. Determination of ultra-trace mercury in seawater by cold atomic fluorescence spectrometry [J]. Chinese Journal of Analytical Chemistry, 1996, 24(2): 247(in Chinese). doi: 10.3321/j.issn:0253-3820.1996.02.003
[9] 蔡慧华, 彭速标. 痕量汞的测定方法进展 [J]. 理化检验-化学分册, 2008, 44(4): 385-390. CAI H H, PENG S B. Progress of methods for determination of trace amounts of mercury [J]. Physical Testing and Chemical Analysis (Part B:Chemical Analysis), 2008, 44(4): 385-390(in Chinese).
[10] 巢静波, 王茜, 王静如, 等. 吹扫捕集-原子荧光光谱与同位素稀释质谱法结合测定海水中痕量汞 [J]. 分析科学学报, 2021, 37(2): 165-170. doi: 10.13526/j.issn.1006-6144.2021.02.005 CHAO J B, WANG Q, WANG J R, et al. Determination of trace mercury in seawater by purge and trap-atomic fluorescence spectrometry combined with isotope dilution mass spectrometry [J]. Journal of Analytical Science, 2021, 37(2): 165-170(in Chinese). doi: 10.13526/j.issn.1006-6144.2021.02.005
[11] 李仲根, 冯新斌, 何天容, 等. 王水水浴消解-冷原子荧光法测定土壤和沉积物中的总汞 [J]. 矿物岩石地球化学通报, 2005, 24(2): 140-143. doi: 10.3969/j.issn.1007-2802.2005.02.009 LI Z G, FENG X B, HE T R, et al. Determination of total mercury in soil and sediment by aqua regia digestion in the water bath coupled with cold vapor atom fluorescence spectrometry [J]. Bulletin of Mineralogy Petrology and Geochemistry, 2005, 24(2): 140-143(in Chinese). doi: 10.3969/j.issn.1007-2802.2005.02.009
[12] 国家质量监督检验检疫总局, 中国国家标准化管理委员会. 海洋监测规范 第4部分: 海水分析: GB 17378.4—2007[S]. 北京: 中国标准出版社, 2008. General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, Standardization Administration of the People's Republic of China. The specification for marine monitoring-Part 4: Seawater analysis: GB 17378.4—2007[S]. Beijing: Standards Press of China, 2008(in Chinese).
[13] 中华人民共和国环境保护部. 水质 总汞的测定 冷原子吸收分光光度法: HJ 597—2011[S]. 北京: 中国环境科学出版社, 2011. Ministry of Environmental Protection of the People's Republic of China. Water quality-Determination of Total mercury-Cold atomic absorption spectrophotometry: HJ 5977-2011[S]. Beijing: China Environmental Science Press, 2011(in Chinese).
[14] EPA. Method 1631, Revision E: Mercury in water by oxidation, purge and trap, and cold vapor atomic fluorescence spectrometry[S]. US: 2002. [15] 罗国兵, 姜惟惟. 王水消解/冷原子吸收测定污泥总汞方法的改进 [J]. 中国给水排水, 2012, 28(6): 91-93. doi: 10.3969/j.issn.1000-4602.2012.06.024 LUO G B, JIANG W W. Improvement on method for determination of total mercury in municipal sludge with aqua regia digestion/CVAAS [J]. China Water & Wastewater, 2012, 28(6): 91-93(in Chinese). doi: 10.3969/j.issn.1000-4602.2012.06.024
[16] 王璐, 杨胜香, 李仲根, 等. 水浴消解-冷原子荧光法测定植物总汞的消解体系选择 [J]. 矿物岩石地球化学通报, 2022, 41(1): 151-155. doi: 10.19658/j.issn.1007-2802.2021.40.093 WANG L, YANG S X, LI Z G, et al. Selection A water bath-based digestion system combined with cold vapor atomic fluorescence spectrometry to determine total mercury in plants [J]. Bulletin of Mineralogy, Petrology and Geochemistry, 2022, 41(1): 151-155(in Chinese). doi: 10.19658/j.issn.1007-2802.2021.40.093
[17] 中华人民共和国生态环境部. 近岸海域环境监测技术规范 第三部分 近岸海域水质监测: HJ 442.3—2020[S]. 北京: 中国环境科学出版社, 2020. Ministry of Ecology and Environment of the People's Republic of China. Technical specification for offshore environmental monitoring Part 3 offshore seawater quality monitoring: HJ 442.3—2020[S]. Beijing: China Environmental Science Press, 2020(in Chinese).
[18] 中华人民共和国国家环境保护总局. 水质 汞的测定 冷原子荧光法: HJ/T 341—2007[S]. 北京: 中国环境科学出版社, 2007. State Environmental Protection Administration of the People's Republic of China. Water quality-Determination of mercury-cold atomic fluorescent spectrophotometry: HJ/T 341—2007[S]. Beijing: China Environmental Science Press, 2007(in Chinese).
[19] 赵健, 张林楠, 雷永乾, 等. 顶空固相微萃取-电热解塞曼原子吸收光谱法测定水中总汞 [J]. 分析化学, 2021, 49(8): 1393-1401. doi: 10.19756/j.issn.0253-3820.211133 ZHAO J, ZHANG L N, LEI Y Q, et al. Determination of trace total mercury in water by headspace solid phase microextraction and electropyrolytic zeeman atomic absorption spectrometry [J]. Chinese Journal of Analytical Chemistry, 2021, 49(8): 1393-1401(in Chinese). doi: 10.19756/j.issn.0253-3820.211133
[20] 周巧丽, 郭鹏然, 潘佳钏, 等. 活性炭富集-电热塞曼原子吸收光谱法测定水中痕量的汞 [J]. 分析化学, 2016, 44(8): 1270-1276. doi: 10.11895/j.issn.0253-3820.160247 ZHOU Q L, GUO P R, PAN J C, et al. Activated carbon enrichment combined with pyrolysis Zeeman atomic absorption spectroscopy for determination of trace amounts of mercury in water [J]. Chinese Journal of Analytical Chemistry, 2016, 44(8): 1270-1276(in Chinese). doi: 10.11895/j.issn.0253-3820.160247
[21] 倪子月, 程大伟, 刘明博, 等. 热解析富集-能量色散X射线荧光光谱法对溶液中汞的测定 [J]. 光谱学与光谱分析, 2022, 42(4): 1117-1121. doi: 10.3964/j.issn.1000-0593(2022)04-1117-05 NI Z Y, CHENG D W, LIU M B, et al. The detection of mercury in solutions after thermal desorption- enrichment by energy dispersive X-ray fluorescence [J]. Spectroscopy and Spectral Analysis, 2022, 42(4): 1117-1121(in Chinese). doi: 10.3964/j.issn.1000-0593(2022)04-1117-05
[22] 高心岗, 吴得福, 李洪杰, 等. HG-DBD-AFS测定地下水中铅砷汞 [J]. 环境工程, 2017, 35(s1): 192-194,50. GAO X G, WU D F, LI H J, et al. Determination of lead, arsenic and mercury in groundwater with HG-DBD-AFS [J]. Environmental Engineering, 2017, 35(s1): 192-194,50(in Chinese).
[23] 赵小学, 赵宗生, 王玲玲. 水中汞的电感耦合等离子体-质谱法测定 [J]. 中国测试, 2013, 39(6): 50-52. ZHAO X X, ZHAO Z S, WANG L L. Determining mercury in water by ICP-MS [J]. China Measurement & Test, 2013, 39(6): 50-52(in Chinese).