Derivative spectrophotometric determination of praseodymium in rare earth mixtures with lomefloxacin

Praseodymium forms a Pr(LMFX)3 complex with lomefloxacin. In this paper, the absorption spectra of the complex has been investigated by applying conventional and derivative spectrophotometric methods. It was found that lomefloxacin could form a stable complex with praseodymium in the pH 6.5–8.5 media. The absorption intensity of the complex is 4.5-fold more than PrCl3. Using the second derivative spectra, the sensitivity is 7.4 times higher for Pr than in the normal method (zero derivative spectra). The second derivative spectrophotometry for determination of praseodymium in the presence of other rare earths has been developed. The calibration curves were linear in the range of 3.5–65 μg ml−1 for Pr. The detection limit is 0.85 μg ml−1. The method is satisfactory for the determination of praseodymium in mixed rare earths.