Sensitive and selective spectrophotometric determination of palladium(II) ion following its preconcentration using modified magnetite nanoparticles and 3-phasic backextraction

We report on a method for selective extraction and backextraction for the ultra-sensitive determination of Pd(II). Magnetite nanoparticles modified with sodium dodecyl sulfate were used to extract Pd(II) as its green 1-(2-pyridylazo)-2-naphtholate complex prior to zero- and first-derivative spectrophotometric determination at 659 and 681 nm, respectively. A sample volume of 70 mL was backextracted with 0.50 mL of n-butanol in a 3-phasic system. The effects of reaction time and the other variables were optimized. The enrichment factor is 134 and the calibration plots are linear in the range from 2 to 90 ng mL(-1) of Pd(II). The detection limit is 0.3 ng mL(-1) and the relative standard deviations and recoveries at levels of 10 and 72 ng mL(-1) of Pd(II) are in the range from 1.1-4.9%, and from 98.5-102.6%, respectively. Most ions do not significantly interfere. The method was successfully applied to the determination of Pd(II) in water and urine samples, alloys, and palladium catalysts.