Abstract
A simple and rapid preconcentation technique, based on collecting trace elements on a membrane filter and dissolving the membrane filter with them in an organic solvent, has been applied to the spectrophotometric determination of titanium(IV). Titanium(IV), 0.510μg in 30500 ml of sample solution, is collected as titanium(IV)/Tiron/Zephiramine ion pair on a polyethersulfone membrane filter, the membrane filter with the ion pair is dissolved in 5 ml of dimethylsulfoxide (DMSO), and the absorbance of the DMSO solution is measured at 382 nm against a reagent blank. A calibration graph is linear over the range 0.5010.0 μg of titanium(IV) in 5 ml of the final DMSO solution. The molar absorptivity is 1.45 × 104l mol-1 cm-1. Six replicate determinations for a sample containing 10.0μg of titanium(IV) give a mean absorbance of 0.606 with a relative standard deviation of 2.1 %. The detection limit, defined as three times the standard deviation of the reagent blank, is 0.1 μg l-1 of titanium with 100-fold preconcentration. Fe(III), V(V), Mo(VI) and W(VI) interfere, but Fe(III) is masked with EDTA.
