常压辉光放电微等离子体激发源与光化学蒸气发生联用检测水体中的痕量铁

doi:10.3964/j.issn.1000-0593(2019)05-1366-06

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摘要：基于原子发射光谱法原理（AES），通过常压辉光放电（APGD）与光化学蒸气发生（PVG）联用发展了一种简单，快速，灵敏的检测水体中痕量铁的方法。含Fe溶液与甲酸混合后进入紫外灯（UV lamp）反应生成Fe的挥发性物种，然后被载气带入到APGD激发源激发并由Maya 2000 pro微型光谱仪检测。为了获得最佳的分析性能，实验优化了氩气流速，样品流速，甲酸浓度，pH值以及放电电流等系列实验参数。Fe的发射信号强度随着氩气流速，样品流速和pH值的变化趋势都是先增大后减小，其中，氩气流速，样品流速和pH值分别为300 mL·min^-1，2.6 mL·min^-1和3.5时Fe发射信号最佳；甲酸浓度在10%~50%（V/V）范围内，随着甲酸浓度升高Fe的发射信号不断增强，但甲酸浓度过高会使APGD激发源稳定性变差，综合考虑甲酸浓度选择为40%（V/V）；放电电流在10~35 mA范围内随着放电电流升高Fe的发射信号不断降低，但放电电流低于10 mA时APGD产生放电等离子体会不稳定甚至熄灭，综合考虑放电电流选择为12 mA。在最优实验条件下，PVG-APGD-AES方法检测Fe（249.8 nm）的检出限（DL）达2.1 μg·L^-1，并且方法稳定性良好，多次测定相对标准偏差（RSD）为2.5%（n=9）。实验还评估了Cd²⁺，Mg²⁺，Ca²⁺，Au⁺，Zn²⁺，Mn²⁺，K⁺，As⁵⁺，Al³⁺，Cr³⁺，Ni²⁺和 Cu²⁺等一系列干扰元素对PVG-APGD-AES方法检测Fe的干扰，回收率在87.6%~107.2%之间，结果表明了这些共存离子不会显著干扰Fe的测定。此外，实验还通过测定Fe的标准参考物质（GSB 07-1188-2000）验证了该方法的准确性，测定值与参考值一致证明PVG-APGD-AES测定Fe是准确可靠的。上述这些结果表明所提出的简单，可靠，廉价的PVG-APGD-AES方法有望用于野外痕量Fe的检测。

关键词：常压辉光放电；光化学蒸气发生；原子发射光谱；铁；野外

Abstract：A simple, novel atomic emission spectrometer (AES) based method for the determination of trace iron ion in water sample was proposed by atmospheric pressure glow discharge (APGD) coupled with photochemical vapor generation (PVG). The Fe solution mixed with formic acid was going through an ultraviolet (UV) lamp to generate volatile specie of iron and then entering the APGD excitation source for excitation and detection with microspectrometer. Several working conditions were optimized to acquire best analytical performance such as argon flow rate, sample flow rate, concentration of formic acid, pH value, and discharge current. The increase of argon flow rate, sample flow rate, and pH value along with the Fe signal intensity was increasing to a maximum value and then decreasing with similar trend. The optimal values of the argon flow rate, the sample flow rate, and the pH value were 300 mL·min^-1, 2.6 mL·min^-1, and 3.5, respectively. The Fe signal intensity increased with the increase of formic acid concentration from 10% to 50% (V/V) but the formic acid concentration with 40% (V/V) was selected when taking the stability of discharge into consideration. The Fe signal intensity decreased with the increase of discharge current from 10 to 35 mA. When the discharge current was below 10 mA, the plasma was unstable and easy to extinguish and the discharge current at 12 mA was selected. Under the optimal operating conditions, the detection limit (DL) for Fe (249.8 nm) was 2.1 μg·L^-1 and the relative standard deviation (RSD) was 2.5% (n=9) with the proposed PVG-APGD-AES. The interferences caused by a series of metal elements including Cd²⁺, Mg²⁺, Ca²⁺, Au⁺, Zn²⁺, Mn²⁺, K⁺, As⁵⁺, Al³⁺, Cr³⁺, Ni²⁺, and Cu²⁺ in determining Fe using PVG-APGD-AES method were examined separately and the recoveries were all in the range of 87.6%～107.2%. The accuracy of the proposed method was validated by the determination of certified reference material (GSB 07-1188-2000) and the results agreed well with the certified value. The results suggested that the developed simple, robust, and cost-effective PVG-APGD-AES is promising for the determination of trace Fe in field.

Key words：APGD; PVG; AES; Fe; In field

收稿日期: 2019-01-22 修订日期: 2019-03-22

中图分类号:

O657.31

基金资助: 国家自然科学基金项目（21822405，41673014），国家重点研发计划项目（2017YFD0801202）和湖北省自然科学基金项目（2016CFA038）资助

通讯作者: 朱振利 E-mail: zlzhu@cug.edu.cn

作者简介: 杨春，1989年生，生物地质与环境地质国家重点实验室博士研究生 e-mail：cyang_cug@163.com

引用本文:

杨春，姚思琪，郑洪涛，朱振利. 常压辉光放电微等离子体激发源与光化学蒸气发生联用检测水体中的痕量铁[J]. 光谱学与光谱分析, 2019, 39(05): 1366-1371.
YANG Chun, YAO Si-qi, ZHENG Hong-tao, ZHU Zhen-li. Determination of Trace Fe in Water Sample by Atmospheric Pressure Glow Discharge Microplasma Coupled with Photochemical Vapor. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2019, 39(05): 1366-1371.

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