COMPARISON OF HYDRAZONE DERIVATIVES FOR REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Several hydrazones having similar structures and different donating atoms were synthesized and used as precolumn chelating agents of metal chelates for HPLC. The relationship between the HPLC selectivities for metal chelates and the donating atoms of hydrazones was also evaluated. The hydrazones were synthesized from corresponding hydrazines and aldehydes by refluxing in ethanol. Hydrazone chelates was insoluble in water. The chelates were prepared with methanol-water mixture or dimethylformamide-water mixture. Most of the hydrazone chelates had absorption maxima near 400 nm. The eluents were methanol -water mixtures, which contained tetrabutylammonium bromide as necessary. The HPLC selectivities of hydrazones for metal ions were higher than the selectivities of complexation. The tridentate hydrazones gave more chelate peaks than the bidentate hydrazones did. The hydrazones made from 4-phenyl-3-thiosemicarbazide gave more peaks than the hydrazone made from benzoylhydrazine.