The synthesis and spectral properties of new radioiodinated indolealkylamines like 2-[131I]-iodo-N,N-dimethyltryptamine, 2-[131I]-iodo-N-methyltryptamine, 2-[131I]-iodo-5-methoxy-N,N-dimethyltryptamine, 2-[131I]-iodio-5-hydroxy-N,N-dimethyltryptamine (2-[131I]-iodo-bufotenine), and 2-[131I]-iodo-tryptamine and the known 2-[131I]-iodo-N-acetly-5-methoxy-tryptamine (2-[131I]-iodo-melatonine) are...