Abstract/Summary

Mass spectrometry (MS) is a sensitive and specific analytical method often used for biological samples and assays. Its widespread application for screening is restrained by the limited sample throughput compared to traditional photometric assay readouts. In this work, the suitability of mass spectrometry using liquid atmospheric pressure matrix-assisted laser desorption/ionisation (LAP-MALDI) as an ionisation technique for high speed MS analysis and screening of biochemical assays was investigated. In a first step, a substrate and product of an enzymatic assay were detected at 5 samples/s without prior sample clean-up. More complex samples (milk) were analysed at 1 samples/s. After further improvements in hardware and software, the analysis of a second enzymatic assay was accelerated to 16 samples/s and peptide standards were analysed at 40 samples/s. This is faster than other MS-based methods reported in the literature and also highly competitive with photometric readouts. Additionally, a systematic study of various components often used in biochemical screening assays and generally biological mass spectrometry on the ion signal of a peptide mixture was carried out. Although pronounced ion suppression was observed with some additives, compounds such as the surfactant octyl-β-D-glucopyranoside and the buffer tricine were found suitable with LAP-MALDI MS analysis. In summary, LAP-MALDI allows for rapid MS sample analysis, the fast readout of biochemical assays and shows great potential for high-throughput screening. Possible improvements by enhanced automation are also discussed.