PRECONCENTRATION AND DETERMINATION OF TRACE CADMIUM USING 1-(2-PYRIDYLAZO)-2-NAPHTHOL (PAN) IMMOBILIZED ON SURFACTANT-COATED ALUMINA

Abstract

The preconcentration of trace cadmium from water samples for a flame atomic absorption spectrometry (FAAS) determination was studied using alumina modified with sodium dodecyl sulfate (SDS) and 1-(2-pyridylazo)-2-naphthol (PAN). A sample solution up to 1000 ml containing μg Cd at pH 10.2 was passed through a microcolumn packed with 1.5 g sorbent at a flow rate of 5 mL min⁻¹. The cadmium collected on the column was eluted with 10 ml of 2 M nitric acid, and then determinated by FAAS. Recovery was greater than 97%. A concentration factor of 100 can be achieved by passing 1000 ml of sample through the microcolumn. The relative standard deviation (10 replicate analyses) at the 20 ng ml⁻¹ level for cadmium was 1.6% and the corresponding limit of detection (based on 3σ) was 24.3 ng L⁻¹. The method was applied to the determination of Cd in waste, tap and mineral waters.

Keywords:

• Cadmium determination
• Atomic absorption spectrometry
• Surfactant
• 1-(2-Pyridylazo)-2-naphthol

ACKNOWLEDGMENT

Support of this investigation by the Research Council at the University of Tehran through Grant No. 514/1/427 is gratefully acknowledged.