In the past, the challenges facing this range of applications within the industry included the fact that there was a lack of appropriate hardware to track reactions under realistic conditions. Also, there was a lack of software to process the data properly, and present it appropriately.
In this article, we discuss solutions to these challenges in the form of integrated hardware and software platforms (InsightMR and InsightXpress) which are set to revolutionise on-line and in-situ reaction monitoring. Further, these platforms are entirely compatible with the standard laboratory based NMR infrastructure from Bruker and therefore data, together with associated insights derived from multiple approaches (on-line, in-situ and at-line) can be easily merged.
Comparison of At-line, On-line and In-Situ Monitoring5 The long-established at-line approach to analysing a chemical reaction with NMR has been to extract a sample (or multiple samples) from the reaction under study, for subsequent analysis in a central analytical laboratory. This is an intrusive and labour intensive practice. In addition, at-line has the important disadvantage of being slow, with cycle times (i.e. from the reaction actually occurring, to results being presented) being in the range of tens of minutes.
In contrast, the on-line configuration from Bruker uses the InsightMR flow tube and samples the reaction directly from a reaction vessel, then circulates the sample through the magnet system. This on-line approach is carried out in a controlled manner, so that temperature and pressure are not affected (Figure 1). The time delay for on-line monitoring using such a system is typically less than one minute.
In a more recent development, in-situ monitoring is made possible through the use of the InsightXpress unit (Figure 2). In this configuration, reactants are mixed inside the magnet and quickly pumped into the NMR probe through a capillary with a delay of only 130 milliseconds. (Note that this a remarkably short time period, and is a key aspect of the performance of the InsightXpress flow tube). Overall, insightXpress enables very fast reactions (with half-lives as short as a second) to be tracked via NMR spectroscopy.