Quality control in combinatorial chemistry: determinations of amounts and comparison of the "purity" of LC-MS-purified samples by NMR, LC-UV and CLND.

The absolute purities of 20 purified samples from a combinatorial library have been determined by a new method that uses the DMSO sidebands [1J[13C-1H]] as an internal standard for quantification. The obtained absolute amounts are compared with the amounts of sample obtained by weighing, with the calculated weights obtained by chemiluminescent nitrogen detection (CLND) chromatography and with the relative purities obtained by LC-UV chromatography.