Determination of Abacavir in maternal plasma, amniotic fluid, fetal and placental tissues by a polarity switching liquid chromatography/tandem mass spectrometry method.

A rapid and efficient high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) method for the determination of concentrations of the carbocyclic nucleoside antiviral Abacavir in maternal rat plasma, amniotic fluid, placental and fetal tissue samples has been developed and validated. All tissue samples were homogenized in water prior to analysis and all samples were prepared by acetonitrile precipitation followed by dilution with HPLC-grade water. Separation of the analyte and internal standard from the matrices was achieved on a C(8) analytical column (2.1 x 150 mm, 5 microm particle size). The mobile phase consisted of 10 mM ammonium acetate/acetonitrile using a gradient method at a flow rate of 0.25 mL/min for all matrices. The method yields retention times of approximately 3.4 and 5.1 min for the internal standard (Azidouridine) and Abacavir, respectively. For all matrices the limit of detection was approximately 1 ng/ml. Recoveries from the different matrices ranged from 53-87% for Abacavir and from 69-84% for Azidouridine. Within- and between-run precision (%RSD) and accuracy (%Error) were under 15% for all matrices.