Abstract: In the drug discovery process, chemists are charged with the task of synthesising compounds with the ultimate aim of producing a clinical candidate. With the aid of combinatorial chemistry, it is hoped that the number and diversity of compounds available for screening will increase, the time taken to optimise a lead will decrease and ultimately the time from the initial high-throughput screen to selection of a clinical candidate will be minimised. In our combinatorial chemistry effort, all compounds are prepared in a single compound per well format and are tested in solution. The advantages of this approach are that it is compatible with all screening methods, and no deconvolution is necessary once an active compound is identified. Before submission to either therapeutic biology or high throughput screening (HTS), each compound is characterised by HPLC for purity and MS for identity. Finally, the mass of each compound is obtained. This not only allows for the calculation of a yield, but also helps further downstream in that quantitative HTS data can now be obtained.