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 (T TA) complex with dibenzo-18-crown-6 (DB18C6) comprises synergistic ext raction and back extraction combined with flame photometry. The effect of various factors (solvent, size of crown ether, reagent concentrati on, shaking time, preconcentration factor, foreign ions etc.) on the e xtraction and back extraction of barium has been investigated. The bar ium 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 so dium 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.