ABSTRACT
The gas Chromatographic behaviour of the ternary complexes of selected bivalent first-row transition metal ions with 1,1,1,5,5,5-hexafluoro-2,4-pentanedione H(HFA), and di-n-butylsulphoxide, DBSO, was studied. Calibration plots of peak area vs. amount of metal injected were linear over a range of 60-900 ng for manganese(II), iron(II), cobalt(II) and nickel(II). The average relative standard deviation was less than 3.0% for all the metals studied. Detection limits of 60, 109, 112 and 115ng for cobalt(II), nickel(II), iron(II) and manganese(II), respectively, were obtained with flame-ionization detection. Various liquid phases, including OV-1, SE-30, and Dexsil 300 were used. The best results were obtained on columns of 5% Dexsil 300. No appreciable thermal decomposition was observed on stainless-steel or glass columns, but the best formed peaks were obtained on all-glass columns. The elution of the metallic species was confirmed by venting the exit gases from the gas chromatograph directly into an atomic-absorption spectrophotometer.
ABSTRACT
The synergic solvent extraction of zinc(II), cadmium(II), and lead(II) with 1,1,1,5,5,5-hexafluoro-2,4-pentanedione, H(HFA), and tri-n-butyl phosphate (TBP) or di-n-butylsulphoxide (DBSO) as neutral donors, into cyclohexane has been investigated. Quantitative extraction occurs at pH 4.5-6.0 in extraction times of 10-30 min, depending on the metal species. The optimum pH, equilibration time, stoichiometry and stability of the extracted species, as well as the effect of fluorinated beta-diketone concentration, metal concentration and neutral donor concentration on the extraction are reported. The extracted species was found to be M(HFA)(2).2DBSO or M(HFA)(2).2TBP by mass-action studies. Thermogravimetric analysis of the complexes is reported. The gas chromatographic behaviour of the ternary complexes of the three metals has also been studied. A calibration plot of peak area vs. the amount of zinc injected was linear over the range 40-900 ng of zinc for the Zn(HFA)(2). 2DBSO species; the cadmium and lead species apparently decomposed on the column and useful chromatographic peaks were not observed. The calibration plot for zinc was determined on the basis of the averages of 3-5 replicate determinations for 14 different concentrations over the range stated. The average relative standard deviation was 2.9%.
