The N,N-dimethyltryptamines: N,N-dimethyltryptamine (DMT), 5-methoxy-N,N-dimethyltryptamine (5-OMe-DMT) and 5-hydroxy-dimethyltryptamine (bufotenin) were completely derivatized to trimethylsilyl (TMS) derivatives with the TMS substituent on the indolic nitrogen. The GLC data of the derivatives and the MS data of combined GC-MS analysis are described. The secondary amines N-methyltryptamine (NMT) and N-methylserotonin (NMS) gave more than one derivative but in the reaction indolic NH was found to be more reactive than the secondary amino NH. Primary amines reacted with CS2 to give isothiocyanates which have good GC properties and are ideally suited for GC-MS studies.