A Turning Tide
Two-dimensional LC-MS brings important benefits to the fields of pharma, biopharma, omics, and natural product analysis.
At the start of the 21st century, we saw an enormous focus on LC×LC at scientific conferences, but attention has now turned to heart-cut 2D-LC – a trend driven by industry (particularly biopharma), where analysts typically do not have the luxury of time-consuming method development. The rise of heart-cut 2D-LC was triggered in part by the introduction of interfaces composed of cartridges containing stationary phase in between the two dimensions, which makes the 2D-LC approach more generic, and hence more approachable for a wider audience of users.
Some chromatographers see 2D-LC and MS as competitors – I believe they must be seen as “partners in crime!” 2D-LC-MS offers some important benefits above and beyond 1D-LC-MS across pharma, biopharma, omics, and natural products:
- Increased resolution: additional chromatographic resolution from the second dimension allows users to identify more compounds when analyzing highly complex samples.
- MS compatibility: where an MS-incompatible mobile phase is used in the first dimension, an interface including stationary phase can easily be used to trap the compounds of interest and desalt, prior to sending the fractions to the second dimension and finally to MS detection.
- Ion suppression: for ‘dirty’ samples, the first dimension can be used as a sample clean-up step, allowing full use of the power of the MS after an orthogonal separation in the second dimension.
Ion mobility can aid in the separation of compounds, and hence also in 2DLC, but until now it has only been suitable for certain applications. The first results with the Waters Cyclic IMS (introduced at ASMS 2019) have been very exciting in this respect.
With the dramatic improvements in UHPLC over the last decade, hardware and software development for 2D-LC will (and should) focus on making instruments easier to use, more flexible and more generic, combined with easier data interpretation, so that a wider range of users can make use of this exciting technology.
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Isabelle François completed her PhD in 2009 in Pat Sandra’s lab at the University of Ghent. Isabelle currently works at Waters, where she has recently become involved in the introduction and support of new technologies, using her expertise in ultra-high performance LC, SFC, comprehensive and heart-cutting two-dimensional fluid based chromatography (LC×(2)LC and SFC×LC) in combination with optical detectors and MS.