A high capacity LC/MS system for the bioanalysis of samples generated from plate-based metabolic screening

HPLC/MS is a linear technique characterized by serial injection and analysis of individual samples. Parallel-format high-throughput screens for druglike properties present a significant analytical challenge. Analysis speed and system ruggedness are key requirements for bioanalysis of thousands of samples per day. The tasks involved in LC/MS analysis are readily divided into three areas, sample preparation/liquid handling, LC/MS method building/sample analysis, and data processing. Several automation and multitasking strategies were developed and implemented to minimize plating and liquid handling errors, reduce dead times within the analysis cycle, and allow for comprehensive review of data. Delivering multiple samples to multiple injectors allows the autosampler time to complete its wash cycles and aspirate the next set of samples while the previous set is being analyzed. A dual-column chromatography system provides column cycling and peak stacking and allows rapid throughput using conventional LC equipment. Collecting all data for a compound into a single file greatly reduces the number of data files collected, increases the speed of data collection, allows rugged and complete review of all data, and provides facile data management. The described systems have analyzed over 40,000 samples per month for two years and have the capacity for over 2000 samples per instrument per day.