Chelometric Titrations Using Azoarsonic Acid Indicator

摘要: Arsenazo STA3-(2-arsonophenylazo)-4,5-dihydroxy-2,7naphthalenedisulfonic acid, trisodium salt! is an excellent indicator for the EDTA titration of rare earths and yttrium in weakly acid solution. In many cases, use masking agents or a simple preliminary separation permits determination samples containing foreign metal ions. Aluminum masked by sulfosalicylate, interference from calcium magnesium avoided proper pH control. Small amounts uranium, iron, most divalent metals are diethyldithiocarbomate; larger these removed exraction their diethyldithiocarbamate complexes. Thorium interferes with earths, but can be titrated at more acidic pH. Titration thorium presence uranium possible. (auth)