Thermospray liquid chromatographic—mass spectrometric analysis of anti-AIDS nucleosides: quantification of 2',3'-dideoxycytidine in plasma samples

Thermospray liquid chromatography—mass spectrometry was investigated as a method for quantification of 2',3'-dideoxycytidine (DDC) from human plasma. A stable isotope analog of DDC ([ 15N 2, 2H 2]DDC) was used as an internal standard. Selected ion monitoring of the protonated molecular ions for DDC and the internal standard was used to record mass chromatograms. The areas of the peaks in the mass chromatograms were used for quantification. The detection limit of DDC in this assay was 50 pg on-column. The calibration curve was linear over the desired range, 0.25–20 ng/ml. The major advantages of this assay over others are: no derivatization, high sensitivity, high specificity and short assay time.