Computer controlled micropreparative isolation and enrichment from GC capillary columns and subsequent sample handling

Abstract

AbstractThis paper describes a computerized system for micropreparative enrichment of components from a mixture being separated on a capillary column. All electronic components are commercially available. Programming was performed in BASIC so that users can easily adapt the program to their own special needs.The enrichment procedure is based on a repetitive absorption of eluting compounds after separation from a capillary column, by sucking them through an absorption tube mounted at the outlet splitter. In order to perform this procedure reliably, the system searches for reference peaks which can stem from componetns of the mixture or from deliberately added reference compounds. Use of error diagnostics prevents contamination of the collected fractions in case of system failures. Optimization is easily performed during a supervised GC run in a semiautomatic mode. Using the function keys of the computer, the operator can adjust injection volume, measure the base line drift at any retention time, and perform reference peak allocation and peak switching until optimal conditions have been found.The system presented has been in operation for several years in our laboratory where, in some cases, the mixture had to be injected onto the capillary column over 500 times to obtain the amount of pure component (10–1000 μg) necessary for NMR structure elucidation. However, recording of meaningful spectra of such small amounts requires special precautions in sample handling. This technique can also be applied for sample recovery after analysis by non‐destructive elucidation methods or by chemical microreactions without loss.