基于双还原体系与膜进样质谱快速测定15N加富水样中的方法*

罗 畅 宋国栋 刘素美

罗 畅1, 2, 3宋国栋1, 2①刘素美1, 2

(1. 中国海洋大学 深海圈层与地球系统前沿科学中心/海洋化学理论与工程技术教育部重点实验室 山东青岛 266100; 2. 青岛海洋科学与技术试点国家实验室 海洋生态与环境科学功能实验室 山东青岛 266237; 3. 中国海洋大学化学化工学院 山东青岛 266100)

15N加富样品; 硝化; 氨基磺酸; 膜进样质谱

Tab.1 Some main methods, principles, and characteristics for the determination of 15N labeled

1 材料和方法

1.1 测定15N加富样品中的分析步骤

图1 基于镉柱与氨基磺酸双还原体系并结合膜进样质谱测定15N加富样品中的简单流程

整个方法涉及多项因素的条件测试, 影响因素和条件设定如表2, 方法的条件测试具体步骤见1.2～1.5, 方法对样品的应用测试见1.6。

1.2 镉柱还原率及还原硝酸盐浓度范围测定

Tab.2 Influencing factors and conditions for determination of by membrane injection mass spectrometry based on cadmium column and sulfamic acid double reduction (SA) system

1.3 氨基磺酸浓度、试剂酸度及反应时间

1.4 线性范围、精密度及检测限

检测限: 以工作曲线线性回归方程截距标准偏差的3倍除以斜率即检测限。

1.5 盐效应

1.6 石老人沙滩沉积物中铵氧化与亚硝酸盐氧化速率的测定

于2019年5月15日早上08:30 (低潮位时刻)在青岛石老人沙滩(36°5′48″N, 120°28′25″E)获取沉积物柱状样, 将表层10 cm沉积物以2 cm的垂向分辨率现场进行分割装入密封袋中; 获取沉积物的同时获取5 L海水, 与分割好的沉积物一同保存在装有冰盒的保温箱带回实验室进行后续实验。

2 结果与讨论

2.1 镉柱还原率

镉柱还原率≤1, SA还原效率≤1, 为实现转化率越大, 则需和越接近1。

图2 过柱(a), 过柱(b), 不过柱(c), 过柱与过柱(d)工作曲线

图3 不同氨基磺酸(SA)浓度(0.5～20 mmol/L)和酸度(HCl浓度0～1 mol/L)条件下, 转化为29N2的信号比值Δ29N2/ΣN2变化(a)和转化率(b)

Fig.3 The signal ratio Δ29N2/ΣN2 variation from to 29N2 (a) and conversion (b) under different sulfamic acid (SA) concentration (0.5～20 mmol/L) and acidity (expressed as HCl concentration 0～1 mol/L)

图4 10 μmol/L经镉和15 mmol/L SA (1 mol/L HCl)试剂还原后测试信号随时间的变化

2.3 线性范围、检出限和精密度

图5 镉柱还原-SA反应测定的线性范围测试

图6 镉柱还原-SA反应测定的工作曲线(0～10 μmol/L)

Tab.3 Δ29N2/ΣN2 average measured at 1 and 10 μmol/L of standard and the Δ29N2/ΣN2 standard deviation and Δ29N2/ΣN2 relative standard deviation (n = 4)

2.4 盐效应影响

通过测定盐度范围为0～35的Δ29N2/ΣN2与盐度为0时Δ29N2/ΣN2信号比值计算相对误差(图7), 表明当盐度为5、30和35, Δ29N2/ΣN2相对误差明显低于1%, Δ29N2/ΣN2基本未发生变化; 当盐度为10～25, Δ29N2/ΣN2相对误差约为2%, Δ29N2/ΣN2受到的影响也较小。因此, 整个反应过程可视为无显著的盐效应。

图7 盐度为0～35时Δ29N2/ΣN2相对误差变化

2.5 石老人沙滩沉积物中潜在的铵氧化与亚硝酸盐氧化速率

图8 加富样品(a)和加富样品(b)中生成与培养时间的关系

Fig.8 Relationship between production and incubation time in -enriched samples (a) and -enriched samples (b)

图9 氧化为及氧化为的速率与沉积物深度的关系

3 结论

致谢 感谢谢成军同学对本研究实验过程与仪器操作所提供的协助; 感谢广西大学海洋学院宁志铭老师对本文的修改指正。

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LUO Chang1,2,3, SONG Guo-Dong1, 2, LIU Su-Mei1, 2

(1. Frontiers Science Center of Deep Ocean Multispheres and Earth System/Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China; 2.Laboratory for Marine Ecology and Environmental Science, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China; 3. College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China)

15N enriched sample; nitrification; sulfamic acid; membrane injection mass spectrometry

*国家自然科学基金, U1806211号, 42076035号, 41606093号; 中国海洋大学中央高校基本科研业务, 202072001号。罗畅, 硕士研究生, E-mail: 1051392235@qq.com

宋国栋, 副教授, E-mail: gsong@ouc.edu.cn

2021-10-09,

2021-12-02

P734

10.11693/hyhz20211000237