Abstract
An optical sensor has been designed for the determination of cobalt by spectrophotometry. The sensing membrane is made by immobilizing methyltrioctylammonium chloride on a triacetylcellulose membrane. In the presence of Co(II) and thiocyanate ions, the colorless membrane changes to blue. The response time of the optode was about 7 min. The sensor can readily be regenerated with 0.02 mol L−1 sodium oxalate solution. This optode is stable and can be stored under water for more than a month without reagent leaching. The calibration curve was linear in the range of 8.5×10−6–1.3×10−4 mol L−1 of Co(II) ion with a limit of detection 5.9×10−6 mol L−1. The relative standard deviations for seven replicate measurements of 3.4×10−5 and 1×10−4 mol L−1 of Co(II) were 1.58 and 1.10%, respectively. The sensor was successfully applied to the determination of cobalt in food samples and vitamin B12 ampoule.
Acknowledgments
The authors are grateful to Shahid Chamran University Research Councils for financial support.