Quantification of 5′-monophosphate cytosine arabinoside (Ara-CMP) in cell extracts using liquid chromatography–electrospray mass spectrometry

A LC/MS/ESI method is described to monitor 5′-monophosphate cytosine arabinoside (Ara-CMP) formed after incubation of an Ara-C prodrug in cell extracts. After addition of an internal standard and off-line treatment with perchloric acid, Ara-CMP is separated from Ara-C and endogeneous matrix components on a porous graphitic carbon stationary phase using gradient elution with a water/acetonitrile mobile phase containing formic acid. The results of method performances (accuracy, linearity, limit of quantification and repeatability) show that the method is acceptable for its intended use.