Investigation of the in vitro biotransformation of R-(+)-thalidomide by HPLC, nano-HPLC, CEC and HPLC--APCI-MS.

High-performance liquid chromatography (HPLC), nano-HPLC, capillary electrochromatography (CEC) and on-line HPLC-atmospheric pressure chemical ionization mass spectrometry (APCI-MS) techniques were used for the identification and detailed characterization of two new metabolites of the former sedative drug thalidomide (TD). The advantages of nano-HPLC and CEC are higher peak efficiency and a drastic decrease in the analysis time, which, together with lower sample dilution during the analyses, allowed to obtain a detection sensitivity that was comparable to HPLC with common-sized columns. Both, nano-HPLC and CEC could be realized in the commercially available capillary electrophoresis system HP3D. On-line HPLC-APCI-MS coupling is a very useful technique for the rapid identification of metabolites without any need for reference compounds.