COLUMN PRECONCENTRATION OF TITANIUM IN ALUMINUM AND ZINC-ALLOYS WITH OXALIC ACID-ASCORBIC ACID AND THE ION-PAIR OF SODIUM 1,2-DIHYDROXYBENZENE-3,5-DISULFONIC ACID AND TETRADECYLDIMETHYLBENZYLAMMONIUM CHLORIDE SUPPORTED ON NAPHTHALENE USING SPECTROMETRY

A solid ion-pair compound produced from sodium 1,2-dihydroxybenzene-3,5-disulphonic acid (Tiron) and tetradecyldimethylbenzylammonium chloride(TDBA) supported on naphthalene in a simple glass-tipped funnel tube provides a simple adsorbent system for preconcentrating titanium from some alloys. Titanium reacts with Tiron to form a water-soluble coloured chelate anion which in turn forms a water-insoluble stable titanium/Tiron/TDBA complex with the ion-pair on the surface of naphthalene packed in a column. Titanium is quantitatively retained on the naphthalene in the presence of L-ascorbic acid and oxalic acid in the pH range 3.0-4.5 and at a flow-rate of 1 ml/min. The metal complex and naphthalene were dissolved from the column with 5 ml of dimethylformamide(DMF), and the absorbance of the solution was measured at 398 nm. A calibration graph was linear over the range 1-18-mu-g of titanium in 5 ml of the final DMF solution. The complex has a molar absorptivity of 1.39 x 10(4) l. mole-1. cm-1 and a sensitivity of 3.44 x 10(-3) mu-g/cm2 for 0.001 absorbance. Eight replicate determinations for a sample containing 12-mu-g of titanium gave a mean absorbance of 0.697 with a relative standard deviation of 0.82%. The interference of various ions was studied and optimum conditions were developed for the determination of titanium in various aluminium and zinc alloys.