Abstract N-([18 F] fluoroalkyl)-N-nitroso-4-methyl-benzensulfonamides [n-alkyl=(− CH 2)[18, 19 F] F, n= 2–4)] were synthesized in radiochemical yields ranging from 75–90% to provide new secondary labelling precursors for the syntheses of 18 F-labelled compounds. Preliminary decomposition studies utilizing the corresponding non-radioactive 19 F- compounds as well as the bromo containing analogous compounds were performed to ...