Chelators, capable of creating soluble complexes with metals, may disrupt the natural speciation of metals in environmental matrices. Detection of environmental speciation of such complexes has remained challenging as obtaining the precise inherent nature of metal-chelator complexes is difficult by using routine techniques. Herein, we report a rapid and sensitive technique for the speciation analysis of complexes of five metal ions (Ni, Pb, Co, Fe and Ca) with two aminopolycarboxylate chelator variants, namely, EDTA (ethylenediaminetetraacetic acid) and EDDS (ethylenediamine-N,N'-disuccinic acid), including the simultaneous quantification of those complexes. EDTA is characterized as environmentally persistent among the chelators used in the current work whereas EDDS is biodegradable. The speciation analysis was performed using ultra-performance liquid chromatography-quadrupole/time-of-flight mass spectrometry (UPLC-Q-TOF-MS). The separation was achieved by using hydrophilic interaction liquid chromatographic column. The effect of various operating parameters on analytes such as mobile-phase composition, buffer concentrations and pH, sample diluents, sample injection volume, and column temperature on the peak shape and sensitivity were systematically optimized. The dilution was the only requirement for preparing the samples for analysis. The average relative uncertainty was 2.4% with the average precision (as RSD, n= 7) of 3.5%. For the metal-EDTA complexes, LOD range was 3 to 76 nmol L^–1 with satisfactory recovery from a simulated mix matrix (recovery: 79–97%) and river water by standard addition (recovery: 82–94%) . For metal-EDDS complexes, LOD range was 66 to 293 nmol L^–1 with recovery from a simulated mix matrix (recovery: 56–97%) and river water by standard addition (recovery: 61–91%). The proposed method will be applicable in speciation analysis and simultaneous detection of metal-chelator complexes from environmental samples.

螯合剂能够与金属形成可溶性络合物，可能会破坏环境基质中金属的自然形态。此类复合物的环境形态检测仍然具有挑战性，因为使用常规技术很难获得金属螯合剂复合物的精确固有性质。在此，我们报告了一种快速、灵敏的技术，用于对五种金属离子（Ni、Pb、Co、Fe 和 Ca）与两种氨基多羧酸螯合剂变体（即 EDTA（乙二胺四乙酸）和 EDDS（乙二胺-N， N'-二琥珀酸），包括这些复合物的同时定量。在当前工作中使用的螯合剂中，EDTA 的特点是环境持久，而 EDDS 是可生物降解的。使用超高效液相色谱-四极杆/飞行时间质谱（UPLC-Q-TOF-MS）进行形态分析。采用亲水作用液相色谱柱实现分离。系统优化了各种操作参数对分析物的影响，例如流动相组成、缓冲液浓度和 pH、样品稀释剂、样品进样量以及柱温对峰形和灵敏度的影响。稀释是制备分析样品的唯一要求。平均相对不确定度为 2.4%，平均精度（RSD，n=7）为 3.5%。对于金属-EDTA 配合物，LOD 范围为 3 至 76 nmol L ^–1 ，从模拟混合基质（回收率：79–97%）和标准添加河水中获得满意的回收率（回收率：82–94%）。 对于金属-EDDS 配合物，LOD 范围为 66 至 293 nmol L ^–1 ，从模拟混合基质中回收（回收率：56-97%），通过标准添加从河水中回收（回收率：61-91%）。该方法将适用于环境样品中金属螯合剂复合物的形态分析和同时检测。