Determination of the rotational energy barriers of atropisomeric polychlorinated biphenyls

A spectrophotometric method for the simultaneous determination of Co, Cu, and Fe in ternary mixtures by means of 1,10-phenanthroline as a complexing agent was developed. The influence of chemical variables affecting the analytical reaction was evaluated. A principal component regression procedure was used to assess spectrophotometric data obtained from nineteen calibration solutions. The method was validated by applying it to the analysis of synthetic mixtures over the concentration ranges 0–407 μmol Co/L, 0–189 μmol Cu/L, and 0–143 μmol Fe/L. It was also successfully employed for the analysis of two cobalt magnetic alloys. The relative errors in the determinations were less than 7% in most cases.