Evaluating the Potential of HPLC with IMS-MS for Metabolomics
January 1st 2017Multidimensional liquid chromatography strategies are the most widely used method for increasing the number of spatially resolved components and reducing stress on mass spectrometric detection. However, the stress placed on a secondary dimension in a comprehensive on-line methodology is very high. An increasingly attractive approach is the coupling of high performance liquid chromatography (HPLC) with ion mobility spectrometry hyphenated to mass spectrometry (IMS-MS). Tim Causon and Stephan Hann of the University of Natural Resources and Life Sciences in Vienna, Austria, spoke to The Column about their work evaluating this approach and exploring its possibilities for metabolomics.
The LCGC Blog: HPLC Troubleshooting Tips–Poor Equilibration in Gradient HPLC
December 12th 2016Our technical support center deals with many issues regarding irreproducibility of retention and selectivity in reversed phase HPLC. Very often, the problem lies in poor equilibration of the HPLC column between injection, which in gradient HPLC can affect the separation selectivity as well as analyte retention.
The Challenge of Accurate Protein Bioanalysis
December 7th 2016In recent years, liquid chromatography–tandem mass spectrometry (LC–MS/MS) methods have been increasingly adopted as a replacement for ligand‑binding assays to monitor the fate of drugs in vivo. Such bioanalysis of protein-based pharmaceuticals (biopharmaceuticals) is more challenging, however, than it is for small-molecule drugs. Rainer Bischoff of the University of Groningen in the Netherlands has been exploring approaches to overcome these challenges. He recently spoke to us about this work.
The LCGC Blog: Partnering to Monitor the Effects of Fracking
December 7th 2016In 2011, when we first began field and laboratory studies to help assess the potential environmental impacts of unconventional oil and gas extraction (UOG), there was very little literature on the subject. Further, the polarizing nature of the topic made it quite difficult to navigate the middle ground. While some voices contended that UOG was perfectly safe, others insisted that it should be banned in its entirety because it is destroying the environment. As with any topic that is both complex and elicits the attention of a large number of people (like our past election or politics, in general), my skepticism forces me to believe that the answer actually lies somewhere in the middle of extreme views.
Methodology for Removing Dihalomethane Carryover from Solid-Phase Microextraction Fibers
December 1st 2016Solid-phase microextraction (SPME) in conjunction with gas chromatography–mass spectrometry (GC–MS) is a simple and effective way to sample analytes. Ordinarily the coated fiber is rid of compounds during desorption in the GC, allowing for the analysis of a new sample. Carryover of the analyte between samples, however, is a problem with many chemicals. Our data shows that heating the fiber in a high temperature injection port for only 2 min between runs prevents carryover. The short heating between samples improves the linearity of the peak area versus concentration relationship over four orders of magnitude of concentration, with a limit of detection below 10-7 M in every case. Although carryover is an acknowledged problem with SPME fibers, such short conditioning steps are rarely considered as a means to eliminate it; this study suggests that they should be evaluated as an option.
Investigation of Reequilibration in Hydrophilic Interaction Liquid Chromatography
December 1st 2016Interest in chromatography using hydrophilic interaction liquid chromatography (HILIC) has continued to build in recent years. Adoption of the technique has been slowed by experiences of poor reproducibility. In particular, re-equilibration times in HILIC have been reported as being exceptionally long as compared to reversed-phase chromatography. In this study, re-equilibration times in HILIC, for both aqueous–organic gradients and buffer gradients are systematically explored. The results not only promise to improve method development practices, but also provide insight into HILIC retention mechanisms across mechanistically differing polar stationary phases.