Spectrophotometric determination of traces of vanadium in cements by solvent extraction with N-benzoylphenylhydroxylamine
Determination of trace elements in cement. V.
1968 Volume 17 Issue 7 Pages 836-842
Details
1968 Volume 17 Issue 7 Pages 836-842
Traces of vanadium in portland cement was determined by spectrophotometric method after extraction of vanadium into benzene with N-benzoylphenylhydroxylamine (BPA).
A sample is dissolved in perchloric acid, and silica, being made insoluble, is filtered off. Vanadium in the filtrate is converted completely into the vanadium(V) state with potassium permanganate, the excess of which is then disintegrated with hydrochloric acid. Vanadium(V) in the aqueous solution adjusted to about 3.4 N as hydrochloric acid is extracted into benzene with BPA, and the absorbance of the benzene phase is measured at 530 mμ.
The extracted vanadium(V)-BPA complex has a composition of 1 to 2 (metal to ligand), and shows an absorption maximum at 530 mμ. There exists a linear relationship between the amount of vanadium extracted and the absorbance. The molar extinction coefficient at 530 mμ is 4, 500. The diverse ions usually found in cements do not interfere with the determination except titanium(IV) and chromium(VI) in large amounts. The modified procedures are also given for these cases.
As little as 0.001% vanadium in cement was determined with satisfactory results, and about 0.0010.005% of vanadium was found in commercial products.
