ALKYLSULPHONIC ACID ION-PAIRING WITH RADIAL COMPRESSION COLUMNS FOR DETERMINING PLASMA OR CEREBROSPINAL-FLUID 1-BETA-D-ARABINOFURANOSYLCYTOSINE IN PEDIATRIC PHARMACOKINETIC ANALYSIS

In order to accurately and precisely measure plasma and cerebrospinal fluid (CSF) 1-beta-D-arabinofuranosylcytosine (Ara-C) in pediatric sam ples with adequate sensitivity and without interference, we have devel oped a reversed-phase ion-pairing technique utilizing the free amino g roup of the pyrimidine ring of Ara-C. Optimum resolution and separatio n was achieved utilizing a 4 mu m C-18 radial compression column. Ara- C and the internal standard 8-bromo-cyclic-AMP eluted at 6.5 and 4.6 m in, respectively, with complete resolution. The minimum detectable amo unt is 2.5 pmol in a 50-mu l volume. The assay was linear in both plas ma and CSF. Intra- and inter-day assay precision were less than 4% and 9%, respectively, for plasma with similar results obtained for CSF. N either endogenous compounds nor commonly co-administered drugs interfe re. Validity for our method was supported by the successful assay of o ver 400 pediatric plasma and 50 CSF samples for pharmacokinetic analys is. The method offers accuracy, precision, sensitivity and efficiency for plasma or CSF Ara-C determination.