Marković Stefan, Levstek Lucija, Žigon Dušan, Ščančar Janez, Milačič Radmila
Department of Environmental Sciences, Jožef Stefan Institute, Ljubljana, Slovenia.
Jožef Stefan International Postgraduate School, Ljubljana, Slovenia.
Front Chem. 2022 May 26;10:863387. doi: 10.3389/fchem.2022.863387. eCollection 2022.
A new analytical procedure for the speciation of chromium (Cr) in plants by high performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was developed using a strong anion-exchange Mono Q column for the separation of the Cr species. To optimize the analytical procedure, Cr complexes were first synthesized from Cr-nitrate with the addition of an excess of ligand (90°C). Cr-oxalate, Cr-malate, Cr-citrate, Cr-aconitate and Cr-quinate complexes and Cr-nitrate (pH 6.5) were chromatographically separated from Cr(VI) by applying linear gradient elution from 100% water to 100% NHCl at a flow rate of 1.5 ml min in 10 min. The column recoveries ranged from 100 to 104%. The exception was Cr-aconitate (column recovery 33%), where a quantitative synthesis was not possible. Good repeatability of the measurements (relative standard deviations better than ± 3%) and low limits of detection (below 0.37 ng ml Cr) were achieved for the individual Cr species. The developed analytical procedure was applied to Cr speciation for dandelions () grown in soil with a high Cr content and a study of the uptake and metabolism of Cr species in dandelions grown in soil with a low Cr content treated with solutions of Cr(VI) or Cr-nitrate (5000 ng ml Cr, pH 6.5) for 48 h. The separated Cr species were quantified by post-column isotope dilution ICP-MS, while the identification was based on retention times and was also supported by mass spectra obtained with high resolution mass spectrometry (HR-MS). The data indicate that for dandelions grown in Cr-rich soil and that treated with Cr-nitrate (pH 6.5), the Cr was mainly accumulated in the roots, while in plants treated with Cr(VI) (pH 6.5), the Cr was evenly distributed between the roots and the leaves. The Cr species found in dandelion roots and leaves were Cr-aconitate, Cr-malate, and Cr-quinate. The results revealed that Cr(VI) was completely reduced and metabolized to Cr(III) complexes. LA-ICP-MS data showed that the Cr in a leaf of dandelion grown in Cr-rich soil was localized mainly at the apex of the leaf.
建立了一种利用强阴离子交换Mono Q柱分离铬形态的高效液相色谱-电感耦合等离子体质谱（HPLC-ICP-MS）分析方法，用于植物中铬（Cr）的形态分析。为优化该分析方法，首先在90°C下由硝酸铬与过量配体合成铬配合物。通过在10分钟内以1.5毫升/分钟的流速从100%水到100%氯化铵进行线性梯度洗脱，将草酸铬、苹果酸铬、柠檬酸铬、乌头酸铬和奎尼酸铬配合物以及硝酸铬（pH 6.5）与六价铬进行色谱分离。柱回收率在100%至104%之间。例外的是乌头酸铬（柱回收率33%），无法进行定量合成。对于各个铬形态，测量具有良好的重复性（相对标准偏差优于±3%）且检测限低（低于0.37纳克/毫升铬）。所建立的分析方法应用于高铬含量土壤中生长的蒲公英的铬形态分析，以及用六价铬或硝酸铬（5000纳克/毫升铬，pH 6.5）溶液处理48小时的低铬含量土壤中生长的蒲公英对铬形态的吸收和代谢研究。分离出的铬形态通过柱后同位素稀释ICP-MS进行定量，而鉴定基于保留时间，并得到高分辨率质谱（HR-MS）获得的质谱图支持。数据表明，对于在富铬土壤中生长以及用硝酸铬（pH 6.5）处理的蒲公英，铬主要积累在根部，而在用六价铬（pH 6.5）处理的植物中，铬在根和叶之间均匀分布。在蒲公英根和叶中发现的铬形态为乌头酸铬、苹果酸铬和奎尼酸铬。结果表明，六价铬完全还原并代谢为三价铬配合物。激光烧蚀电感耦合等离子体质谱（LA-ICP-MS）数据显示，在富铬土壤中生长的蒲公英叶片中的铬主要位于叶尖。
