Determination of Rhodium in Water Samples Using Ion Liquid Based on Ultrasonic Assisted Dispersive Liquid–Liquid Microextraction Coupled with Spectrophotometric Technique

Abstract

Ionic liquid based ultrasound-assisted dispersive liquid–liquid microextraction of trace levels of Rh³⁺ ions from aqueous samples is illustrated, to investigate a rapid and reliable sample pretreatment to determine Rh³⁺ ions spectrophotometrically. The Rh³⁺is converted into its complex with 5-(4`-chlorophenylazo)-6-hydroxy-pyrimidine-2,4-dione (CPAHPD) as a complexing agent, and an ultrasonic bath is used with the ionic liquid, 1-octyl-3-methylimidazolium bis(trifluoromethyl-sulfonyl) imide at room temperature is applied to extract the analyte. The centrifuged rhodium complex is enhanced in the form of ionic liquid droplets and prior to its spectrophotometric analysis, 250 µL ethanol is added to the ionic liquid-rich phase. Finally, the influence of various parameters on the recovery of Rh³⁺ is examined and optimized. Under optimum conditions, the calibration graph is linear in the range of 10–260 ng mL⁻¹, the detection limit is 3.2 ng mL⁻¹ (3Sb/m, n=7) and the relative standard deviation is ± 1.78 % (n=7, C = 150 ng mL⁻¹). Comparison with other procedures, the proposed procedure reduces the danger of exposure to toxic solvents, applied for extraction in conventional extraction procedures, it also requires a shorter extraction time. The method is successfully validated by the analysis of real samples and compared statistically with FG-AAS method. The proposed method is successfully validated by the analysis different complex materials such as environmental water and alloy samples and compared statistically with ETAAS method.