OPTIMIZED SEPARATION OF PURINE-BASES AND NUCLEOSIDES IN HUMAN CORD PLASMA BY CAPILLARY ZONE ELECTROPHORESIS

An optimized separation of the main purine compounds of human serum by capillary zone electrophoresis is presented. Separations were perform ed in an uncoated silica capillary (44 cm x 75 mum I.D., 37 cm to wind ow) on a SpectraPhoresis 1000 system with UV detection. The separation of adenine (Ade), adenosine (Ado), guanine (Gua), guanosine (Guo), hy poxanthine (Hyp), inosine (Ino), xanthine (Xan) and uric acid (UA) was optimized with respect to pH, temperature, applied potential and hydr odynamic injection time. Optimum conditions were 20 mM borate buffer ( pH 9.4), 37-degrees-C, 20 kV and 9 s load and detection at 260 nm. Lin earity extended from 1 to 125 muM. The sensitivity of the method was 0 .5 muM, which is adequate for measuring Ade, Gua, Hyp and UA in plasma samples. Plasma samples from newborns were precipitated with an equal volume of perchloric acid (7%, v/v), the supernatant was adjusted to neutral pH with potassium carbonate and, before injection, the sample was alkalized with sodium hydroxide. The method presented here allows the determination of Ade, Guo, Hyp and UA. The levels of the determine d purines were compared in samples from control newborns, preterm babi es and newborns with asphyxia or acidic serum pH values.