Microscale determination of purines in tissue samples by capillary liquid chromatography with electrochemical detection.

A microscale method for purines involved in intracellular signaling and energy metabolism, including ADP, ATP, cyclic-AMP, NADH and GTP, was developed. The analytes were separated on a fused-silica capillary liquid chromatography column (50 microm inner diameter by 25 cm long) packed with 7 microm reversed-phase particles and detected with a carbon fiber cylinder microelectrode at +1.50 V versus Ag/AgCl reference electrode. With an acetonitrile gradient, the separation was carried out within 15 min. With a 100 nl injection volume, the detection limits varied from 0.9 to 8 fmol depending upon the analyte. The low detection limits make the method suitable for analysis of small tissue samples. As a demonstration of the method, islets of Langerhans were analyzed for their adenosine-related messenger content.