Karlsson Ulrika, Düker Anders, Karlsson Stefan
Man-Technology-Environment Research Centre, Orebro University, Orebro, Sweden.
J Environ Sci Health A Tox Hazard Subst Environ Eng. 2006;41(7):1155-67. doi: 10.1080/10934520600655747.
The two oxidation states of thallium, Tl(I) and Tl(III), were quantified by IC-ICP-MS using complexation of Tl3+ with DTPA (penta-carboxymethyl-diethylenetriamine) and separation on a cation exchange column according to a modification of the method devised by Coetzee et al. In order to avoid successively lowered separation efficiency and loss of resolution during a run, a gradient elution was made using HCl instead of HNO3. With an ultrasonic nebuliser instead of a V-groove nebuliser the limit of detection for Tl(I) and Tl(III) could be lowered from 25 ng/L and 3.0 ng/L to 9.0 ng/L and 0.7 ng/L, respectively, which is adequate for many fresh water systems. The stability of Tl(III) in acidic solutions was found to be concentration dependent, with an initially high reduction rate of Tl(III). Exposure of the sample to light further increased the reduction rate. Addition of DTPA (0.01 mM) and acid (HNO3, 1%) to a sample with 1 mug/L Tl(III) stabilised the Tl(III) content for at least 48 h. Analysis of field samples showed that only acidification is inadequate to maintain the original distribution of Tl(I) and Tl(III). Internal calibration (standard addition) and correction of the analytical signal (205Tl) with a non-ionic internal standard (11B) yielded almost quantitative recoveries of both Tl(I) and Tl(III). A scheme for field sample preparation is proposed, including sampling, storage and pre-analysis treatment.
铊的两种氧化态，Tl(I)和Tl(III)，通过离子色谱-电感耦合等离子体质谱法（IC-ICP-MS）进行定量分析。采用Tl3+与二乙三胺五乙酸（DTPA，五羧甲基二乙三胺）络合，并根据Coetzee等人设计的方法进行改进，在阳离子交换柱上进行分离。为了避免在一次运行过程中分离效率连续降低和分辨率损失，使用HCl代替HNO3进行梯度洗脱。使用超声雾化器代替V型槽雾化器，Tl(I)和Tl(III)的检测限可分别从25 ng/L和3.0 ng/L降至9.0 ng/L和0.7 ng/L，这对于许多淡水系统来说是足够的。发现Tl(III)在酸性溶液中的稳定性与浓度有关，Tl(III)的初始还原速率较高。样品暴露在光下会进一步提高还原速率。向含有1 μg/L Tl(III)的样品中加入DTPA（0.01 mM）和酸（HNO3，1%）可使Tl(III)含量稳定至少48小时。现场样品分析表明，仅酸化不足以维持Tl(I)和Tl(III)的原始分布。采用内标法（标准加入法）并用非离子内标（11B）对分析信号（205Tl）进行校正，可使Tl(I)和Tl(III)的回收率几乎达到定量。提出了一种现场样品制备方案，包括采样、储存和分析前处理。
