Anion exchange liquid chromatography–inductively coupled plasma-mass spectrometry detection of the Co2+, Cu2+, Fe3+ and Ni2+ complexes of mugineic and deoxymugineic acid

CE of phytosiderophores and related metal species in plants

“…However, the biggest problem in nearly all published analytical methods for trace metal speciation is not the detection, but the unknown stability of metal species with respect to the (liquid chromatographic) separation. Such problems were reported for Ni species [23], Fe species [22], and even for PS species that are thermodynamically very stable, partial dissociation may happen on chromatographic columns [26,27]. One solution to this dilemma could be the use of direct methods for metal speciation, i.e., methods that are not based on a preceding separation.…”

“…Both methods are applicable for quantitative analyses of PS in the low micromolar concentration range, but are not well suited for the detection of intact metal species. In the last few years, some hyphenated analytical methods for detection and quantitative determination of metal-PS species have been proposed, based on HPLC with atomic absorption spectrometric detection [22], HPLC with inductively coupled plasma mass spectrometric detection (ICP/MS) [23][24][25][26], or HPLC-ESI/MS [24,25,27]. Clearly, the ICP/MS methods offer very good sensitivity and element specificity, but lack unequivocal identification of unknown species.…”

Evaluation of different column types for the hydrophilic interaction chromatographic separation of iron-citrate and copper-histidine species from plants

“…This holds in particular for separation based methods, because an excess of free ligand is usually separated from metal species during separation (changing the metal to ligand ratio), and also the effective pH may change considerably when organic modifiers (such as methanol in RP or acetonitrile in HILIC) are used. Moreover, and unlike the situation of stable phytosiderophore or nicotianamine chelates which exist always in 1:1 stoichiometry, for iron citrate and copper histidine several stoichiometries and charge states must be considered [21,29] In the last years hydrophilic interaction chromatography (HILIC) has been employed successfully for the separation of metal species by several research groups [9][10][11]23]. It enables new separation possibilities due to the fact that the HILIC partitioning mechanism (as already proposed by Alpert [30]) displays only weak, but very effective, interactions with potentially labile metal species.…”

“…In particular, capillary electrophoresis [7,8] and hydrophilic interaction chromatography [9][10][11] have been applied successfully for their separation. However, even for stable species ligand exchange reactions may occur in the presence of competing ligands and/or redox mediators.…”

Sites, pathways, and mechanism of absorption of Cu-EDDS complex in primary roots of maize (Zea Mays L.): anatomical, chemical and histochemical analysis

“…Cu-EDDS complex, which has an UV absorption characteristics and with negative charge, can be determined by using an ion-exchange high-performance liquid chromatography (Collins et al 2001;Adrian 2002;Knepper et al 2005;Bakkaus et al 2006;Niu and Shen 2009). Rubeanic acid (C 2 H 4 N 2 S 2 ) (also known as Dithiooxamide) can react with divalent Cu 2+ ions to form dark green Cu-rubeanic acid complex precipitation.…”