National Center for Natural Products Research, The University of Mississippi, Oxford, MS, 38677, USA.
Environ Monit Assess. 2011 Jan;172(1-4):51-66. doi: 10.1007/s10661-010-1317-7. Epub 2010 Feb 6.
Determination of solid-bound element concentrations is an important initial step in environmental studies especially for assessment of contamination level, and of origin, relative mobility, and fate of contaminants. This study revealed that a relatively new collision/reaction cell inductively coupled plasma-mass spectrometry is a potent tool for determining total and partially extractable solid-bound element (V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, and Pb) concentrations in a complex matrix solution containing HF and/or HCl. Six different extraction methods commonly used for environmental monitoring studies were tested for their bias and variability using estuarine and marine standard reference materials. Microwave-assisted methods based on concentrated [HNO₃] or [HNO₃ + HF (4:1)] and [HNO₃ + HF + HCl (10:3:2)] were applied for determining pseudo-total and total element concentrations, respectively. Dilute-acids (1 M HNO₃, 1 M HCl, and 0.5 M HCl) were utilized in single-step partial extraction protocols. Except the 0.5 M HCl cold-extraction method which was performed at room temperature, other partial extraction protocols used microwave-digestion. This study demonstrated that the use of microwave-assisted methods in studies aimed at determining the non-residual, non-specific extractable fractions of elements in solid environmental samples may result in overestimation, and thus needs to be re-examined. We believe that the cold extraction method will play a significant role in future environmental monitoring studies. Nevertheless, results of the cold extraction method not accompanied with total element concentrations have limited value, as the amount of extraction may vary significantly with the nature (origin) of the elements, and with the types of the samples. Therefore, we suggest combining microwave-assisted total digestion and 0.5 M HCl cold-extraction methods as a relatively cost- and time-effective, environmentally sound screening procedure for routine environmental monitoring programs involving a large number of samples from diverse geological and anthropogenic settings.
测定固相元素浓度是环境研究的重要初始步骤，特别是对于评估污染水平、污染物的来源、相对迁移率和归宿。本研究表明，一种相对较新的碰撞/反应池电感耦合等离子体质谱法是一种强有力的工具，可用于测定含有 HF 和/或 HCl 的复杂基质溶液中总固相和部分可提取固相元素（V、Cr、Mn、Fe、Co、Ni、Cu、Zn、As 和 Pb）的浓度。使用河口和海洋标准参考物质测试了六种常用于环境监测研究的不同提取方法的偏倚和可变性。基于浓 [HNO₃] 或 [HNO₃+HF(4:1)] 和 [HNO₃+HF+HCl(10:3:2)] 的微波辅助方法分别用于测定准总量和总量元素浓度。稀酸（1 M HNO₃、1 M HCl 和 0.5 M HCl）用于单步部分提取方案。除在室温下进行的 0.5 M HCl 冷提取方法外，其他部分提取方案都使用微波消解。本研究表明，在旨在测定固相环境样品中元素的非残留、非特异性可提取部分的研究中使用微波辅助方法可能会导致高估，因此需要重新检查。我们相信，在未来的环境监测研究中，冷提取方法将发挥重要作用。然而，没有总元素浓度的冷提取方法的结果价值有限，因为提取量可能会因元素的性质（来源）以及样品的类型而有很大差异。因此，我们建议将微波辅助全消解和 0.5 M HCl 冷提取方法相结合，作为一种相对具有成本效益和时间效益、环境友好的筛选程序，用于涉及大量来自不同地质和人为环境的样品的常规环境监测计划。
