With the advent of liquid chromatography/ mass spectrometry and information dependent data acquisition function in mass spectrometry, it has become possible to characterise metabolites while to quantifying their parents during metabolic stability studies. This was once impossible to be analysed in one injection.
The Q TRAP instrument is based on a triple quadrupole ion path and is capable of doing conventional multiple reaction monitoring (MRM) mode quantitation as a tandem mass spectrometry. On top of that it also has several high sensitivity ion trap MS scans using the final quadrupole as a linear ion trap. MS3 spectrum can be obtained from this instrument. Usually MS3 is sufficient to establish the fragmentation cascade because all fragments are generated abundantly without lower mass information cut off comparing to 3D ion traps. The application of this new hybrid RF/DC quadruple-linear ion trap mass spectrometer to the quantitation and characterization of chloramphenicol in its metabolic stability study using rat liver S9 is described. The limit of quantitation is around the parts per billion (ppb) level. In vitro half life has been calculated. Chloramphenicol is mainly metabolized by conjugation with glucuronic acid, which is in a good agreement with USP in vivo data. This technique could be applied widely in drug discovery, such as pharmacokinetic screening, metabolic stability study, etc., as well as food analysis. The quadrupole-linear ion trap proved to be a sensitive and reliable HPLC detection system that provided important chemical structure and quantitation information simultaneously.
Chloramphenicol (CAP) is a wide range antibiotic which interferes with protein synthesis of many gramnegative and gram-positive bacteria, and has toxic effects on humans. The main potential human toxicity is depression of red bl