A b s t r a c t

Anew, simple and highly sensitive dispersive liquid–liquid microextraction method using a ionic liquid, i.e., 1-Butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6]) for nickel determination at trace levels in real samples was developed. Nickel was chelated with diethyl dithiocarbamat reagent and extracted into an ionic liquid. Ni was back-extracted from the IL phase with 200
L of 0.5 mol L-1 nitric acid and determined by electrothermal atomic absorption spectrometry (ETAAS). Various parameters such as pH, amount of ionic liquid, eluent type and volume, chelating agent concentration, volume of the sample solution and matrix interference effect on the recovery of the metal ions have been studied. Under the optimum conditions, the enrichment factor 100 was obtained from only 20 mL of sample. The calibration graph was linear in the rage of 20-700 ng L-1 of nickel with detection limit of 5 ng L-1. The relative standard deviation (R.S.D.s) for eight replicate measurements of 20 ng L-1 of nickel was 5.6%. Validation of the methodology was performed by standard addition method and analysis of certified reference material. The method was successfully applied to the determination of Ni+2 in serum and tap water samples.

Hamid Shirkhanloo, Ahmad Rouhollahi and Hassan Zavvar Mousavi

A b s t r a c t

Arapid and simple procedure was developed for selective and sensitive determination of ultra-trace silver in biological and environmental samples using the electrodeposition on a graphite probe modified with palladium followed by electrothermal atomic absorption spectrometry. Several experimental parameters for the electrodeposition, such as deposition potential, electrolyte concentration, pH of solution and deposition time were optimized. The calibration graph after preconcentration was linear in the range of 10-250 ngL^–1 with correlation coefficient of 0.9989 under the optimum conditions for procedure. The limits of detection (LOD) and quantification (LOQ) base on (3σ) and (10σ) were 2.8 ngL^–1 and 9.4 ngL^–1 respectively. Related standard deviation (RSD) for eight replicatemeasurements of 100 ngL^–1 silver was 4.3%. Samples were digested completely in a closed microwave digestion system using only perchloric acid, and interference owing to various cations was also investigated. The proposed procedure was successfully applied to determine silver in blood, urine and some environmental samples with satisfactory analytical results.

Reza Moradkhani, Ahmad Rouhollahi, Hamid Shirkhanloo and Jahan Ghasemi