A Novel Non-Extractive Sequential Injection Procedure for Determination of Cadmium

Abstract

This paper presents a novel non-extractive procedure for cadmium determination in a sequential injection (SI) system. The reaction is based on the formation of a complex by Cd(II), iodide ions, and 2-[2-(4-dimethylamino-phenyl)-vinyl]-1-ethyl-quinolinium iodide (R), commonly known as Quinaldine red. Complex-formation results in significant changes in the UV-Vis spectrum of R: the peak is significantly broadened and a shoulder appears near 618 nm. It is important to emphasize that no surfactant addition is needed for solubilization of the system. Under the optimum reaction conditions the calibration plot was linear in the range 1.12–11.24 mg L⁻¹ Cd and the detection limit was 0.24 mg L⁻¹ Cd. The method was tested for the analysis of mineral water and pharmaceutical samples spiked with cadmium.

Keywords:

• 2-[2-(4-Dimethylamino-phenyl)-vinyl]-1-ethyl-quinolinium iodide
• Cadmium
• Complexation
• Green analytical chemistry
• Sequential injection analysis

Acknowledgments

This paper was submitted as part of a Special Issue on Flow Injection Analysis.

The authors gratefully acknowledge the following financial support: J. Škrlíková and V. Andruch from the Scientific Grant Agency of the Ministry of Education of the Slovak Republic and the Slovak Academy of Sciences (Grant No. 1/4451/07); H. Sklenářová and P. Solich from the Ministry of Education of the Czech Republic (Grant MSM 0021620822); J. Škrlíková from the project SVV/2011/263002; and J. Škrlíková from the internal grant systems of the Faculty of Science at P.J. Šafárik University in Košice (VVGS Grant No. 24/2009/CH). J. Škrlíková would like to offer special thanks to the International Visegrad Fund for providing a 10-month Scholarship. The authors wish to thank to Dr. Veronika Jalčoviková from the Regional Office for Public Health for her help with carrying out the flame atomic absorption measurements.

Notes

^a (t = 2.262, P = 0.95), t - Student coefficient for n-1 degrees of freedom; n = 10.

^b .

^a using 1.00 mL of pharmaceutical filtrate.

^b using 0.25 mL of pharmaceutical filtrate.