Silver-Ion Liquid Chromatography–Mass Spectrometry

Lipidomic Analysis

“…30 Silver-ion chromatography is a special mode of NP with embedded silver ions, which can differentiate lipids differing in the DB number, positions, and cis/trans geometry and also regioisomers of TG. 31 The current trend in LC is the use of sub-2 mm particles and high-operating pressures (ultrahigh-performance liquid chromatography, UHPLC), which provide superior performance. Another popular tool is the use of two-dimensional (2D) LC, where two chromatographic modes with orthogonal separation selectivity can be coupled to provide higher peak capacities either in offline 27 or online 28 modes.…”

“…45 The same problem with the quantitation of lipids is present in any two-dimensional (2D) HPLC separation, 27,28 because one mode typically resolves lipid classes (HILIC or NP), while the second one is based on lipid species separation (RP) or specific interactions, such as silverion chromatography. 31 The implementation of any type of ion mobility spectrometry results in the same situation as described for 2D that IS is not co-ionized with analytes from the same lipid subclass, but it may provide valuable additional separation dimension for various types of lipid isomers. 46 Data Processing and Reporting.…”

Liquid chromatography at the University of Pardubice: A tribute to Professor Pavel Jandera

“…In writing this article, our aim was not only to provide a remembrance of our former teacher and supervisor and to pay tribute to his remarkable scientific career, but also to bring the reader closer to his contributions to the development of the field of HPLC and, generally, separation sciences. The work was much easier as we were able to build on many review articles authored by Pavel Jandera [1–26], and draw freely on two memoirs, written by himself not long before his unfortunate passing [27, 28].…”

Pattern-Type Separation of Triacylglycerols by Silver Thiolate×Non-Aqueous Reversed Phase Comprehensive Liquid Chromatography

“…The retention mechanism is based on the ability of unsaturated organic compounds to complex with transition metals bonded to the stationary phase. The organometallic complexes are of the charge-transfer type, i.e., the unsaturated compound acts as an electron donor and the silver ion as an electron acceptor [7]; the differences in the strength of the weak reversible complexes formed during the elution process have allowed for the successful separation of TAGs differing in the number and position of double bonds. In general, the retention increases with increasing DBs and distance among them; moreover, the complexes' stability decreases with the increasing chain-length and with an increasing number of substituents at the DB.…”

“…The mobile phase may interact both with the solute and the support material; thus, the proper choice of solvents will affect the selectivity of the separation and the migration of the different species, to an appreciable extent. As for the stationary phase, two techniques have been traditionally employed for embedding Ag + ions in the LC system: by impregnating a support with a silver salt (usually silica gel and silver nitrate, respectively) or by binding the silver ions to an ion-exchange medium, in which Ag + ion replaces the protons of the functional groups (such as -SO 3 H) and forms a stable ionic interaction, or finally, by adding a silver salt to the mobile phase during a conventional RPLC separation (the latter being incompatible with mass spectrometry (MS) detection [7,8]. Besides the cumbersome preparation steps, requiring practice and skill, the major problem related to silver ion LC performed on such columns has consisted in the development of a stable and reproducible system, with a controlled silver content and reasonable operational life.…”