Mobile Tool for HPLC Reaction Monitoring

A mobile HPLC reaction monitoring tool consisting of a cart-mounted microfluidic HPLC instrument equipped with a tethered, automated sampling and dilution module is described. Several examples of the use of the instrument for carrying out reaction progress analysis are presented. Reaction aliquot size is typically only a few microliters, allowing extensive sample monitoring from small volume reactions. Reaction quenching is possible, and aliquot dilution is adjustable, with suitable precision and accuracy even at hundredfold dilution. A sampling capillary with a chemically inert stainless steel fritted terminus allows sampling from some heterogeneous reactions. The sampling interval is adjustable, from a minimum of about 4 min, upwards. Visualization of an ongoing or completed study as either stacked "waterfall" chromatograms or as graphs of integrated peak areas (or any derived function, such as percent ee or percent conversion) vs time affords the process chemist valuable information on reaction kinetics and a useful record of reaction progress over time. While online HPLC analysis has been known for some time, the compact and mobile nature of this instrument renders it especially useful for carrying out reaction progress monitoring in the laboratory environment.