used the compound potassium 2 2 6 6 tetramethylpiperidine 1 oxy 4 xanthate i use diphenylthiocarbazone for example in the same fashion first modifying the molecule by replacing one of its phenyl rings with a spin labeled system such as that used by zolotov with the xanthate the remaining ring can also be used to covalently bond the 34 dithizone 34 to an inert carrier such as carboxymethylcellulose if desired e g see bauman a j anal chem 39 932 935 1967 who used it to extract ultratrace transition metal cations from natural waters this then comprises an additional general refinement to the method described by zolotov as the spin labeled 34 ligand exchange resin 34 can now act both to collect and to signal through its esr behavior the type of metal and the concentration present in the 34 resin 34 it is clear that the esr signals from spin labeled ligands such as dithizone or oxine 8 hydroxyquinoline will provide diagnostic data on the nature and oxidation state of the cations extracted by them into an organic phase or into a ligand exchange resin of which they are the ligands this is because the metal cation complex exhibits structural variation iwantscheff op cit page 86 notes that the dithizonates of the 23 cations with which it complexes exhibit diagnostically significant differences both in the ph of optimal extraction and in the color wavelength of maximum absorption thus the esr signals from the bound metals will also vary and can be detected in real time in field applications it is clear that high explosive molecules such as tnt can be covalently.