SEPARATION AND DETERMINATION OF TRACE AMOUNTS OF BARIUM AS ITS THENOYLTRIFLUOROACETONE COMPLEX WITH DIBENZO-18-CROWN-6 BY MEANS OF SYNERGISTIC EXTRACTION AND FLAME PHOTOMETRY

A new method for the separation and determination of trace amounts of barium at the ppb-ppm level in water as its thenoyltrifluoroacetone (TTA) complex with dibenzo-18-crown-6 (DB18C6) comprises synergistic extraction and back extraction combined with flame photometry. The effect of various factors (solvent, size of crown ether, reagent concentration, shaking time, preconcentration factor, foreign ions etc.) on the extraction and back extraction of barium has been investigated. The barium TTA chelate in o-dichlorobenzene forms stable adducts with DB18C6 [Ba(TTA)2 . nDB18C6, n = 1 approximately 2]; the stability constants (betan) of the adducts determined by means of the curve fitting method are log beta1 = 3.77 and log beta2 = 7.91. The content of barium in sodium chloride and sodium nitrate of guaranteed reagent grade was found to be 9.67 +/- 0.08 mug/g and 7.86 +/- 0.09 mug/g, respectively.