A Sensitive and highly selective spectrophotometric method has been developed for the determination of titanium (IV) using 5-(2`,4`-dimethylphenylazo)-6-hydroxypyrimidine-2,3-dione (I), 5-(2`-methyl-4`-hydroxyphenylaz0)-6-hydroxypyrimidine-2,3-dione (II), and 5-(4`-chloro-phenylazo)-6-hydroxypyrimidine-2,3-dione (III) as chromogenic reagents. Titanium (IV) forms insoluble red complexes in aqueous acidic medium, which can be made soluble bythe action of anionic surfactant. The deep red coloured complexes, having an absorption maximum at 546, 566, and 595 nm, respectively. Beer`s law is obyied over the concentration ranges 0,02-1,80 µg mL-1.Ringboom optimum concentration range were found to be 0.05-1.70 µg mL-1. The molar absorptivity, Sandell sensitivity and RSD were also calculated. Most of the forgein metal ions and anions do not produce any coloration with reagents (i-III) at the optimum conditions. Base4ed on these results, a simple and direct spectrophotometric method with high selectivity and sensitivity was proposed. The method has been successfully applied for the determination of titanium in soil, geo-chemical and silicate rock samples.

Quim. Anal., 21, 217–222 (2002)