Ultrasound-assisted emulsification dispersive liquid-liquid microextraction for preconcentration and determination of cadmium in natural water samples by spectrophotometric technique

Jintana Klamtet

Abstract


The aim of this work was to develop ultrasound-assisted emulsification dispersive liquid-liquid microextraction for preconcentration cadmium in water samples using 4-(2-Pyridylazo) resorcinol (PAR) as complexing agent. In the preconcentration step, the amount of 3 mL acetone (dispersive solvent) containing 150 µL of tetrachloroethylene (extraction solvent) was injected rapidly into the sample solution containing cadmium solution, 4.00 mL 3.0 mmol L-1 of 4-(2-pyridylazo) resorcinol (chelating agent) and 4.00 mL buffer solution pH 10 by using a syringe. In this step, the cadmium/PAR complexes were extracted into the fine droplets of tetrachloroethylene. Then, the fine droplets of tetrachloroethylene were emulsified by ultrasonic bath before centrifugation (5 min at 3000 rpm). Finally, the organic phase containing enriched analytes was separated and determined by UV-Visible spectrometer. Under these optimum conditions, the limit of detection (LOD) was 0.14 mg/L and limit of quantitation (LOQ) was 0.47 mg/L with sensitivity enhancement factor (EF) of 1.26. The proposed method showed the relative standard deviation (RSD) less than 5% and was successfully to apply for the recovery and determination of cadmium in different water samples around Naresuan University. The results showed that the 3 collected samples has amount of cadmium in the range 0.00 – 0.60 mg L-1 and the percentage recovery was in the range 90.3-105.30 %.


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