High-Throughput Analysis of Natural Product Compound Libraries by Parallel LC−MS Evaporative Light Scattering Detection

The application of an 8-way fully automated parallel LC-MS-ELSD system to the analysis of a library of 96 structurally diverse natural products is described. A 10-min separation incorporating a universal gradient allowed elution of 86 of these 96 compounds, all of which were detected by positive or negative mode electrospray ionization in conjunction with ELSD. This method is demonstrated to be one of the most universal means of detection for polar, nonvolatile, thermally labile natural products. It also allows an 8-fold increase in throughput. The analysis and profiling of constituents present in a library derived from plant material of Sarcostemma hirtellum, in terms of their retention times and mass spectra, are shown. This rapid characterization of plant constituents in terms of compound libraries is important in searching for new biologically active compounds. As a high-throughput tool to support our natural product discovery program, this method has been successfully used to analyze a library of 36,000 partially purified fractions derived from plant materials.