Design and Evaluation of a Mercury (II) Optode Based on Immobilization of 1-(2-Pyridylazo)-2-Naphthol on a Triacetylcellulose Membrane and Determination in Various Samples

Abstract

The characterization of an optical sensor membrane is described for the determination of
Hg2+ ions based on the immobilization of 1-(2-pyridylazo)-2-naphthol (PAN) on a
triacetylcellulose membrane. The membrane responds to mercury ions by changing color
reversibly from orange to red in universal buffer solution at pH 6. Under optimum conditions, the
proposed membrane displayed a linear range of 0.1-24 μg mL-1 with a limit of detection of, 0.02
μg mL-1 at a wavelength of 558 nm. The response time of the optode was about 10-12 min,
depending on the concentration of mercury (II) ions. The coefficients of variation (CV) of the
sensor response for, 1.0 μg mL-1
of Hg (II) was, 1.8% and the CV between seven membranes
was 2.3%. The sensor can readily be regenerated with the ethylene diamine solution. The
optode is fully reversible and the selectivity of optode to Hg2+ ions in universal buffer is relatively
good with Co2+ and Ni2+ ions as interferences. The proposed optode was applied successfully
for the determination of mercury (II) in various samples.