Fabrication of optical sensor for nickel (II) analysis

Abstract

The Low-cost optical polymer sensor was developed for the detection of nickel (II) ions in water based on immobilization of dimethylglyoxime (DMG) as a colorimetric reagent on polymer substrates. The sensors were fabricated by 3 different processes including polycaprolactone (PCL) doped with DMG electrospun fibers, PCL doped with DMG film and gelatin doped with DMG film. The critical parameters such as the mass ratio of DMG and PCL, pH of nickel solutions, response time and interference ions were studied. The sensor was responded to nickel (II) ions by forming red-pink color of Ni(DMG)2 complex at pH 9. The optimum mass ratio of DMG and polymer media was found to be 20:80 for PCL/DMG electrospun fiber and film and 3.6:96.4 for gelatin/DMG film. All sensors showed the short response time of 10 minutes. The sensor was provided the response in range of 1-10 mg L-1 with detection limit of 0.22, 0.18 and 0.11 mg L-1 of PCL/DMG electrospun fiber, PCL/DMG film and gelatin/DMG film sensor, respectively. Both of PCL sensors expressed the good selectivity toward nickel(II) ions over cadmium (II), manganese(II) and sodium ions when present at equal concentration. Under the optimum conditions, the accuracy and precision of all sensors were investigated by using spiked water sample with standard nickel (II) solution at two concentration levels (1 and 5 mg L-1).The recovery percentages were 104.4-105.0%, 102.6-104.7% and 94.0-97.9% for PCL/DMG fiber, PCL/DMG film and gelatin/DMG film sensor, respectively. The good precisions in range of 4.8-7.4% were attained for all sensors. The proposed method could be effectively applied for the determination of trace levels of nickel (II) ions in real water samples.