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At the forefront of chemistry and biology research, development timelines are fast‐paced and large quantities of pure targets are rarely available. Herein, we introduce a new framework, which is built upon an automated, online trapping‐enrichment multi‐dimensional liquid chromatography platform (TE‐Dt‐mDLC) that enables: 1) highly efficient separation of complex mixtures in a first dimension (1D‐UV); 2) automated peak trapping‐enrichment and buffer removal achieved through a sequence of H2O and D2O washes using an independent pump setup; and 3) a second dimension separation (2D‐UV‐MS) with fully deuterated mobile phases and fraction collection to minimize protic residues for immediate NMR analysis while bypassing tedious drying processes and minimizing analyte degradation. Diverse examples of target isolation and characterization from organic synthesis and natural product chemistry laboratories are illustrated, demonstrating recoveries above 90 % using as little as a few micrograms of material. [ABSTRACT FROM AUTHOR]

Evaluation of a several fluorine-containing stationary phases for the chromatographic separation of fluorine-containing pharmaceuticals from their corresponding desfluoro analogs revealed a number of perfluoroaryl and perfluoroalky stationary phases that afford good separations. These fluorous stationary phases exhibit greater retention for the fluorine-containing compounds relative to the H-containing analogs, consistent with a fluorophilic retention mechanism. While both perfluoroalkyl and perfluoroaryl stationary phases afford adequate resolution, the perfluoroaryl columns generally exhibit superior separation factor ( α ) and peak efficiency ( N ), resulting in faster baseline separations, with the Hypersil Gold PFP and Poroshell 120 PFP columns providing the best overall performance for the test group studied. [ABSTRACT FROM AUTHOR]

Highlights: [•] During separation on chiral stationary phases an increase in pressure led to an increase of retention factors for some analytes and a decrease for others. [•] During separations on achiral C-18 an increase in pressure always led only to an increase of retention factor. [•] Changes in pressure led to small changes in enantioselectivity. [•] Changes in enantioselectivity may be due to pressure effects on the alpha-helix groove size in chiral stationary phases based on cellulose or amylose. [ABSTRACT FROM AUTHOR]

Ultra high-performance liquid chromatography (UHPLC) utilizes columns packed with sub-2-μm stationary-phase particles and allows operation with pressures of up to 15,000psi to yield increased resolution, speed, and sensitivity versus conventional HPLC. This promising new technology was used for the analysis of energetic compounds (RDX, HMX and CL-20) and a selective method was developed on an Acquity UPLC™. A fast UHPLC method was applied to determine alkaline hydrolysis reaction kinetics of major energetic compounds. Activation energies of alkaline hydrolysis reaction for CL-20, RDX and HMX were comparable to those in literature, however they were determined in a shorter amount of time due to the speed of analysis of the chromatographic method. The use of liophilic salts (KPF6) as mobile-phase additives for the enhancement of separation selectivity of energetic compounds was demonstrated. [Copyright &y& Elsevier]

The separation of basic compounds can be challenging and the use of inorganic mobile phase additives have been successfully used in chromatographic methods development. About fifteen years ago the role of these additives as ion-interaction agents for selectively adjusting retention of ionic analytes was discovered and the theory of chaotropicity was applied to reversed phase chromatography. In the last ten years the studies of the influence of these counterions on the retention of ionizable analytes and the interaction with the stationary phase in various hydro-organic eluents has expanded our knowledge of this phenomenon. The general view and understanding of the process have been significantly updated and the use of these ionic additives (liophilic ions) in the mobile phase has become regular practice in the pharmaceutical industry for optimization and fine tuning of complex separations. This paper reviews the latest developments in the field and discusses the modification and expansion of our theoretical understanding of the process. The paper also describes their application in practical separations for a wide variety of analytes, from small molecules to peptides and even chiral separations. [ABSTRACT FROM AUTHOR]

Chromatographic separation and analysis of complex mixtures of closely related species is one of the most challenging tasks in modern pharmaceutical analysis. In recent years, two-dimensional liquid chromatography (2D-LC) has become a valuable tool for improving peak capacity and selectivity. However, the relatively slow speed of chiral separations has limited the use of chiral stationary phases (CSPs) as the second dimension in 2D-LC, especially in the comprehensive mode. Realizing that the recent revolution in the field of ultrafast enantioselective chromatography could now provide significantly faster separations, we herein report an investigation into the use of ultrafast chiral chromatography as a second dimension for 2D chromatographic separations. In this study, excellent selectivity, peak shape, and repeatability were achieved by combining achiral and chiral narrow-bore columns (2.1 mm x 100 mm and 2.1 mm x 150 mm, sub-2 and 3 µm) in the first dimension with 4.6 mm x 30 mm and 4.6 mm x 50 mm columns packed with highly efficient chiral selectors (sub-2 µm fully porous and 2.7 µm fused-core particles) in the second dimension, together with the use of 0.1% phosphoric acid/acetonitrile eluents in both dimensions. Multiple achiral x chiral and chiral x chiral 2D-LC examples (single and multiple heart-cutting, high-resolution sampling, and comprehensive) using ultrafast chiral chromatography in the second dimension are successfully applied to the separation and analysis of complex mixtures of closely related pharmaceuticals and synthetic intermediates, including chiral and achiral drugs and metabolites, constitutional isomers, stereoisomers, and organohalogenated species. [ABSTRACT FROM AUTHOR]