A novel optical sensor has been fabricated for highly accurate, simple and selective determination of nanomolar levels of cadmium ions. The sensor depends on the interaction of 6-{4-(2,4-dihydroxyphenyl)diazenyl)phenyl}-2-oxo-4-phenyl-1,2-dihydropyri-dine-3-carbonitrile (DDPODC) with Cd(II) in plasticized (2-nitrophenyloctyl ether) (o-NPOE) polyvinylchloride (PVC) membrane incorporating chromoionophore V as a lipophilic H+-selective indicator. It would seem that the higher Cd(II) concentration, the lower absorbance of chromoionophore V in the membrane at 668 nm, whereas the absorbance at 586 nm increased. The developed sensor at pH 4.7 has a linear range of 5.0 × 10-12 - 2.5 × 10-5 M with limits of detection and quantification of 1.62 × 10-12 and 4.95 × 10-12 M, respectively. The relative standard deviation (RSD) for eight determination of 1.0 × 10-7 M Cd(II) was 1.67%. Finally, the proposed sensor gives good results for applications in the direct determination of cadmium ions in water, food, and biological samples. Additionally, we compared the obtained results with the data obtained from the flame atomic absorption spectrometry (FAAS).
Keywords: Azo dyes; Cadmium determination; Environmental analysis; Optical membrane sensor; Spectrophotometry.
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