高效液相色谱-电感耦合等离子体质谱联用检测土壤中的无机硒形态

秦冲; 施畅; 万秋月; 王磊; 刘爱琴; 安彩秀

doi:10.15898/j.cnki.11-2131/td.201803200024

高效液相色谱-电感耦合等离子体质谱联用检测土壤中的无机硒形态

Speciation Analysis of Inorganic Selenium in Soil by High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry

摘要

摘要: 土壤样品中亚硒酸盐Se（Ⅳ）和硒酸盐Se（Ⅵ）的形态分析中，提取剂的选择和检测方法是技术的关键。以往的提取剂容易导致硒形态发生转变或无法同时提取Se（Ⅳ）和Se（Ⅵ），常用的氢化物发生原子荧光光谱法无法直接测定Se（Ⅵ），而是通过差减法得出Se（Ⅵ）含量。本文对比了不同提取剂的提取能力，确定使用0.1 mol/L氢氧化钠溶液作为提取剂，在55℃超声萃取土壤样品30 min，提取液经高效液相色谱分离，电感耦合等离子体质谱检测，建立了土壤中Se（Ⅳ）和Se（Ⅵ）的形态分析方法。采用Hamilton PRP X-100色谱柱，以6 mmol/L柠檬酸为流动相，pH=5.5，在8 min内可完全分离Se（Ⅳ）和Se（Ⅵ），两者的检出限分别为0.15 μg/L、0.16 μg/L，线性相关系数（r²）均大于0.999。以土壤为基体进行加标回收试验，Se（Ⅳ）和Se（Ⅵ）的回收率在84.2%~95.8%之间，相对标准偏差为1.4%~5.3%（n=6）。该方法简单快速，具有良好的精密度和准确度，适用于土壤中无机硒的形态分析。

Abstract:
BACKGROUNDIn the speciation analysis of selenite Se (Ⅳ) and selenite Se (Ⅵ) in soil samples, the key problem is to select the extraction agents and detection methods. In the past, extraction agents may lead to Se species redistribution or cannot extract both Se (Ⅳ) and Se (Ⅵ). Selenium speciation has been routinely determined by Hydride Generation-Atomic Absorption Spectrometry (HG-AAS). However, Se (Ⅵ) cannot be directly measured and its concentration is calculated by the difference between analyzed total Se and Se (Ⅳ) concentrations.
OBJECTIVESIn order to establish an analysis method for the determination of Se (Ⅳ) and Se (Ⅵ) in soil samples by selecting the appropriate extraction agent and determination technique.
METHODSThe extraction capacity of different extraction agents was compared and 0.1 mol/L sodium hydroxide was selected for the experiment. Selenium species were quantitatively extracted in a ultrasonic field at 55℃ for 30 min. An analytical method for determination of Se (Ⅳ) and Se (Ⅵ) by High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry (HPLC-ICP-MS) was established.
RESULTSThe results show that Se (Ⅳ) and Se (Ⅵ) can be separated within 8 min by using a Hamilton PRP X-100 reversed-phase anion exchange column with 6 mol/L citric acid as mobile phase under pH of 5.5. The detection limits of Se (Ⅳ) and Se (Ⅵ) are 0.15 μg/L and 0.16 μg/L, respectively. Linear correlation coefficient (r²) is more than 0.999, the recoveries are 84.2%-95.8%, and the relative standard deviations are 1.4%-5.3% (n=6).
CONCLUSIONSThe proposed method is simple and fast and has good accuracy and high precision, which meets the requirements for analyzing inorganic selenium in soil.

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