LC/MS determination of the enaminones E139, DM5 and DM27 in rat serum.

Enaminones, E139, DM5 and DM27, have been recently recognized as potential anticonvulsant compounds. The molecular masses of these enarminones were proven using ion trap Finnigan mass spectrometer. For conduction of biological studies in animals, a sensitive and selective high-performance liquid chromatography-mass spectrometry (LC/MS) was developed for the determination of the selected enaminones in rat serum. A simple protein precipitation procedure was followed for cleaning up the serum samples before analysis. LC/MS determinations were performed using an APCI probe at 430 degrees C. Positive ions (M+1)(+) were acquired in MS/MS-SRM mode at m/z 308.1 (parent m/z 340.2) for E139 and m/z 262.1 (parent m/z 294.1) for DM5. On the other hand, DM27 and E118 (internal standard) were measured in SIM mode at m/z 236.5 and 222.5, respectively. Quantitation was based on measurement of the peak area ratio of enaminones (E139, DM5, DM27) and E118 as an internal standard. Calibration curves were linear (r>0.9989) over the concentration range 100-1000 ngml(-1) and were free from serum interference. Precision and accuracy studies of control samples showed intra-day and inter-day %RSD <10.1 and % deviation from nominal concentrations (%DEV) from -4.3 to +10.1. Recoveries of E139, DM5 and DM27 from quality control rat serum samples using protein precipitation method were 92.3, 89.4 and 89.6%, respectively. The reported data suggest the utility of this developed method for structural elucidation and for performing pharmacokinetics studies on the selected enaminones in rats.