Introducing macrocyclic glycopeptide columns as unique achiral stationary phases: Insights from hydrophobic subtraction model and in-silico modeling.

Background: The need for stationary phases with unique selectivity in reversed-phase liquid chromatography has been of utmost importance to chromatographers for advancing the analysis of complex samples. Macrocyclic glycopeptide based stationary phases have been widely used for chiral separations with different chromatographic modes such as normal phase, reversed phase, and supercritical fluid chromatography. Given the multimodal retention mechanisms namely π-π complex interaction, hydrogen bonding, dipole-dipole interaction, and strong Coulombic interactions by which analytes are separated using the macrocyclic glycopeptides, these stationary phases are expected to provide novel selectivity when used under the reversed phase for achiral separations.

A Comprehensive 2D-LC/MS Online Platform for Screening of Acetylcholinesterase Inhibitors.

The continuous interest in discovering new bioactive molecules derived from natural products (NP) has stimulated the development of improved screening assays to help overcome challenges in NP-based drug discovery. Here, we describe a unique platform for the online screening of acetylcholinesterase inhibitors without the need for pre-treating the sample. In the current study, we have demonstrated the ability to combine reversed-phase separation with a capillary immobilized enzyme reactor (cIMER) in two-dimensional liquid chromatography system coupled with mass spectrometry detection.

Integrated analytical workflow for chromatographic profiling and metabolite annotation of a cytotoxic Phorbas amaranthus extract.

Phorbas is a widely studied genus of marine sponge and produce structurally rich cytotoxic metabolites. Still, only few studies have assessed metabolites present in Brazilian species. To circumvent redundancy, in this work, we applied and herein report the use of a scouting liquid chromatographic system associate to the design of experiment produced by the DryLab® software to obtain a fast and efficient chromatographic separation of the active hexane fraction, further enabling untargeted high-resolution mass spectrometry (HRMS) data.

A novel on-flow mass spectrometry-based dual enzyme assay.

This work describes a new simultaneous on-flow dual parallel enzyme assay based on immobilized enzyme reactors (ICERs) with mass spectrometry detection. The novelty of this work relies on the fact that two different enzymes can be screened at the same time with only one single sample injection and in less than 6 min. The system consisted of two immobilized capillary enzyme reactors (ICERs).

Natural deep eutectic solvents as the major mobile phase components in high-performance liquid chromatography-searching for alternatives to organic solvents.

Over the past six decades, acetonitrile (ACN) has been the most employed organic modifier in reversed-phase high-performance liquid chromatography (RP-HPLC), followed by methanol (MeOH). However, from the growing environmental awareness that leads to the emergence of "green analytical chemistry," new research has emerged that includes finding replacements to problematic ACN because of its low sustainability. Deep eutectic solvents (DES) can be produced from an almost infinite possible combinations of compounds, while being a "greener" alternative to organic solvents in HPLC, especially those prepared from natural compounds called natural DES (NADES).

Continuous vs. segmented second-dimension system gradients for comprehensive two-dimensional liquid chromatography of sugarcane (Saccharum spp.).

A comprehensive two-dimensional liquid chromatography system in combination with photodiode array and mass spectrometry detection was developed for analysis of polyphenols in sugarcane (Saccharum spp.) leaf extracts. To achieve this, a micro cyano column and a partially porous octodecylsilica column were used in the first and the second dimension, respectively.