Adsorbent Medium Octadecyl silica pH 4.5-7.00 membrane discs modified with pentathia-15-crown-5 Diethyldithiocarbamate 0.5-2.5 mol complex on Amberlite [L.sup.-1] XAD-2000 HN[O.sub.3] 1-phenyl-1,2-propanedione-2- pH 3 complex on oximethiosemicarbazone SP Sephadex C25 Poly(N- pH 0.5 (hydroxymethyl)methacylamide 0-1-allyl-thiourea) hydrogels Dowex M 4195 chelating resin pH 4 Multi-walled carbon nanotubes pH 1-6 2-pyridine-5-(4-tolyl)-1,3,4- 0.5 mol/L hno3 oxadiazole complex on Amberlite XAD-4 Polyethylenimine coated on pH 5.7 [Al.sub.2][O.sub.3] Rubeanic acid
complex on pH 3.5 silica gel Silica gel pH 2 (SG-[CIPrNTf.sub.2]) DEBT complex on Amberlite pH~1 XAD-16 Adsorbent Eluent D.
6,8-Dinitro-1-acetyl-1,2,3,4-tetrahydro-9H-carbazole 1 (0.1 mol, 30.3 g) dissolved in glacial acetic acid (40 mL) refluxed with rubeanic acid (0.1 mol, 12 g) for 3.5 hours, as inspected by TLC.
After this, rubeanic acid (0.120 g, 1mmol) was added and the reaction mixture was checked by TLC after equal irradiation time.
Calcium oxalate in this case was confirmed by the rubeanic acid stain of Yasue.
Perhaps the most reliable method, and the one used in this study, is the Yasue stain, which applies aqueous silver nitrate and rubeanic acid to color oxalate black.