Precipitation reactions of thiobenzoylphenylhydroxylamine and its use as a reagent for copper

Thiobenzoylphenylhydroxylamine (TBPHA) quantitatively precipitates copper as Cu(C₁₃H₁₀NSO)₂ which can be used as a weighing form for copper; the gravimetric factor is 0.12217. Iron, aluminium, chromium and commonly accompanying elements do not interfere. Quantitative precipitation and separation of several metals from highly acidic solutions is possible. The precipitation reactions of metals with TBPHA, over a wide range of acidity and in the presence of EDTA, are tabulated. TBPHA is of little value as a colorimetric reagent.