Unpredictable losses of serotonin in perchloric acid tissue homogenates

In connection with studies regarding the influence of some drugs on brain m aldevelopment. monoamine transmitters and their metabolites were analyzed i n rat striatum and hypothalamus of rat brain. A serious instability of the indole-containing analytes, particularly the serotonin was determined in pe rchloric acid tissue homogenates. On the contrary, homogenizing the brain t issue in phosphate buffer at pH 3.5 with some additives as the analytical m obile phase, helped to stabilize the compounds of interest. In order to eva luate the extent of the losses, striata from the left and right hemispheres of twelve animals were homogenized half-and-half in both perchloric acid a nd the phosphate buffer and the yields were compared. The yields of seroton in were lowered 33% whereas that of hydroxindoleacetic acid were of 11% in average, provided that the perchloric acid was used as the homogenizing age nt. A comparison of our present investigations with some previous findings in rather scanty reports is discussed. These results can be of interest to evaluate true absolute concentrations of the transmitters and their metabol ites by HPLC-EC detection.