This article describes the stacked injection functionality of Shimadzu's Nexera UC Prep system to improve the efficiency of preparative operations.
Preparative processes are used in a wide variety of fields, such as for selectively screening seed or lead compounds from newly synthesized compounds, or for structural analysis of impurities in pharmaceuticals or components with specific functional properties in natural substances. Preparative supercritical fluid chromatography (preparative SFC) is widely used in the pharmaceutical industry and many other fields because it can shorten analysis times and simplify post-processing. For analysis involving a limited number of peaks, such as when separating isomers of chiral compounds, stacked injection can improve the efficiency of preparative purification. This report describes an example of using the stacked injection functionality of the Nexera UC Prep preparative supercritical fluid chromatograph system to improve the efficiency of preparative operations.
Shorter Analysis Times Using SFC
Due to the low viscosity and high diffusivity of supercritical carbon dioxide, column back pressure for SFC is low even at high flow rates. That means analysis speeds can be increased without sacrificing column efficiency. Consequently, significantly shorter analysis times can be expected than with HPLC.
Stacked injection is a technique that improves the efficiency of preparative
operations by successively injecting additional samples and utilizing the time spent waiting for peak elution. Functionality for stacked injection is included in SIL-40 autosampler and FRS-40 sampler and fraction collector.
Stacked Injection Settings
Settings for stacked injection can be specified easily in LabSolutions workstation software. The presence of any overlapping peaks can be confirmed easily by specifying [Injection Interval], [Number of Injection],
and [Wait Time to Next Pretreat] settings, and using the single run results (chromatogram) to simulate results for the given injection interval.