I have been separate piperidine alkaloid isomers with ordinary normal phase silica TLC, revealed with Draggendorf's reagent. However now I am attempting some separations using a silver-nitrate impregnated TLC system and Draggendorf will not stain anything on them. I have tried ammonium molibdate (I think 'Hanessian's Stain') with no success. Please would anyone offer further suggestions?
Thanks in advance