The Chromatography Forum

of Delaware Valley

The rise of miniaturized and portable instrumentation has enabled the analysis of complex samples directly at the point of need using a variety of measurement techniques. In both academic and industrial settings, on-line reaction monitoring by liquid chromatography (LC) taken directly at the sampling site can be achieved using compact LC platforms. Here, a bench-scale imine condensation was monitored via on-line LC-UV-MS using a compact capillary-scale LC coupled to a single quadrupole MS. A syringe pump was set to continually draw from a reaction vessel and through the injection loop of the LC. The entire platform including the reaction vessel all fit within a single, standard-size chemical fume hood. The low injection volumes (4-40nl) compatible with capillary-scale columns used in this system allow for flow rates of 0.5µl/min as a withdraw speed in order to minimize the overall sample loss due to sampling. Chromatographic flow rates between 1-2µl/min were used, reducing both the cost of mobile phase and the waste generated during reaction. By using the peak areas of both the UV and MS signal the relative quantities of both reactant and product can be monitored over the course of the reaction, allowing for further studies into reaction kinetics under various conditions.