LCGC Europe-11-01-2016

On-line two-dimensional liquid chromatography (2D-LC) embracing mainly comprehensive LC (LC×LC) and multiple heart-cutting LC (mLC–LC) offers new opportunities for in-depth characterization of pharmaceuticals. Reversed-phase LC × reversed-phase LC using different column chemistries and mobile phases provides good orthogonality for a wide range of applications related to small molecule drugs. Moreover, hardware configurations and software are now commercially available to perform LC×LC and mLC–LC measurements in a reproducible manner.

A chiral ionic liquid, namely 1-ethyl-3-methyl imidazole L-tartrate ([EMIM][L-Tar]), was applied as a new chiral ligand for the separation of tryptophan, tyrosine, and phenylalanine enantiomers by chiral ligand exchange capillary electrophoresis (CE). To validate the unique behaviour of [EMIM][L-Tar], the performance of L-tartaric acid and 1-ethyl-3-methyl imidazole L-proline as chiral ligands was investigated to make a comparison with [EMIM][L-Tar]. Then the separation mechanism was further discussed. It was proven that [EMIM][L-Tar] was a good chiral ligand and would have good application prospects in separation science.

What could be causing a peak to be eluted before the column dead time?

Blood is perhaps the most widely used sample fluid in bioanalysis. Dried blood spot (DBS) sampling has been used in clinical applications for more than 50 years, but it is recently seeing a resurgence of interest. DBS sampling holds several advantages associated with the use of small sample sizes obtained via finger pricks, including simplicity and biohazard reduction. In the previous instalment, we gave an overview of microsampling in bioanalysis (1). This month, we dig deeper into bioanalysis using DBS sampling.

This month’s “GC Connections” continues the discussion of procedures for safe setup, use, and disposal of compressed gas cylinders in the chromatography laboratory.

Although enzyme immunoassay (EIA) is a prevalent screening technique, it is also prone to issues such as high false positive rates because of lack of analyte specificity. Mass spectrometry was therefore investigated as an alternative screening technique for the ability to improve analyte specificity on a comparable time scale. In this study, a rapid on-line sample preparation and injection (ROSPI) method was developed using a commercially available guard cartridge on a conventional liquid chromatography–tandem mass spectrometry (LC–MS/MS) system. Using a two-point calibration curve to provide semi-quantitation, a robust method was developed and validated that improved upon the high false positive rate observed in immunoassay screening.

The 41st International Symposium on Capillary Chromatography (ISCC) and the 14th GC×GC Symposium will return to the city of Fort Worth “Gateway to the West”, Texas, USA, in 2017.

Click the title above to open the LCGC Europe November 2016 regular issue, Vol 29, No 11, in an interactive PDF format.