Restriction capillaries as an innovative mixing unit for intermediate mobile phase exchange in multidimensional analysis

Automated Sequential Analysis of Hydrophilic and Lipophilic Fractions of Biological Samples: Increasing Single-Injection Chemical Coverage in Untargeted Metabolomics

“…However, it leads to very bulky and expensive configurations and was not tested in this work. The method presented by Loos et al in 2017 [ 24 ], using restriction capillaries to obtain a flow differential, showed promise as a possible alternative and was initially compared to the direct approach using the BSM2 pump presented in this work ( Figure 1 ). As far as technical aspects go, both methods performed well and without any direct issues.…”

“…In this study, the focus was to develop methods for the analysis of pharmaceuticals in environmental samples. The protocol of Cabooter et al was later refined by Loos et al in 2017 who demonstrated a novel mixing unit utilizing what they called restriction capillaries [ 24 ]. A somewhat different approach was taken by Wang et al in 2017 who used a pre-column to separate the lipidome from the metabolome for sequential lipidomics/metabolomics analysis [ 25 ].…”

Current developments in LC-MS for pharmaceutical analysis

“…For complex samples, containing a mixture of compounds with a large variety in physicochemical properties (e.g., containing both very polar and very apolar compounds), even the most efficient columns can often not resolve all important peaks in the chromatogram 80,81 . In this case, twodimensional liquid chromatography (2D-LC) techniques can be employed to increase the separation capacity.…”

A systematic investigation of the effect of sample solvent on peak shape in nano- and microflow hydrophilic interaction liquid chromatography columns

“…Hydrophilic interaction chromatography (HILIC), firstly proposed in 1990 [1], has become a powerful tool for the analysis of polar drugs, metabolites and biologically important compounds in proteomics, glycomics and clinical analysis [2][3][4][5]. It has gained increasing attention over the last few years due to its complementary selectivity with reversed-phase liquid chromatography (RPLC), its ability to retain polar molecules and its interesting applicability for LC-MS and 2D-LC [3,6,7]. The retention mechanism of HILIC is quite complex.…”