APPLICATION OF A NOVEL, PLASTIC FORMED CARBON AS A PRECOLUMN PACKING MATERIAL FOR THE LIQUID-CHROMATOGRAPHIC DETERMINATION OF ACETYLCHOLINEAND CHOLINE IN BIOLOGICAL SAMPLES

A novel carbon material, plastic formed carbon (PFC), was prepared by mixing various amounts of pure graphite with an organic binder and pyr olysing the mixture to ''glassy carbon'' at a modest final temperature of 1000-1400 degrees C. This preparation procedure allows more conven ient and precise control of the final graphite adsorption characterist ics. Various PFC materials were constructed and tested both as bulk ad sorbents and as precolumn packings for the direct determination of ACh and Ch in brain tissue homogenates. The PFC precolumns prepared from 12.5-50% graphite, by mass, were capable of selectively removing inter fering species while not adsorbing any of the desired quaternary amine analytes. The usually large solvent front was also dramatically reduc ed with these precolumns. These PFC precolumns are useful for the dire ct determination of ACh and Ch in brain tissue homogenates and other b iological samples.