Iron is an important nutrient essential for plants and critical for human health. The state-of-the art of methods for iron speciation in cereal grains and plant fluids is critically reviewed. Particular attention is given to the latest developments in the coupling of HPLC with the parallel ICP MS and electrospray ionization (ESI) MS/MS detection, usually QTOF MS or Q-Orbitrap MS, for the identification and quantification of iron species. The coupled techniques allow the direct microanalysis of plant intracellular fluids (xylem and phloem) and complement X-ray absorption spectroscopy (XANES and EXAFS). The increasing resolution and sensitivity of electrospray mass spectrometers and emergence of software allowing extraction of iron specific data from large chromatographic data sets are responsible for the growing role of electrospray MS/MS in speciation studies. The use of stable isotopes for the probing of the reactivity and stability of endogenous metal complexes and quantitative analysis are rising in importance.

Auranofin, a gold­(I)-based complex, is under clinical trials for application as an anticancer agent for the treatment of nonsmall-cell lung cancer and ovarian cancer. In the past years, different derivatives have been developed, modifying gold linear ligands in the search for new gold complexes endowed with a better pharmacological profile. Recently, a panel of four gold­(I) complexes, inspired by the clinically established compound auranofin, was reported by our research group. As described, all compounds possess an [Au­{P­(OMe)3}]+ cationic moiety, in which the triethylphosphine of the parent compound auranofin was replaced with an oxygen-rich trimethylphosphite ligand. The gold­(I) linear coordination geometry was complemented by Cl–, Br–, I–, and the auranofin-like thioglucose tetraacetate ligand. As previously reported, despite their close similarity to auranofin, the panel compounds exhibited some peculiar and distinctive features, such as lower log P values which can induce relevant differences in the overall pharmacokinetic profiles. To get better insight into the P–Au strength and stability, an extensive study was carried out for relevant biological models, including three different vasopressin peptide analogues and cysteine, using 31P NMR and LC-ESI-MS. A DFT computational study was also carried out for a better understanding of the theoretical fundamentals of the disclosed differences with regard to triethylphosphine parent compounds.