A Paper-Based Analytical Device Based on Combination of Thin Film Microextraction and Reflection Scanometry for Sensitive Colorimetric Determination of Ni(II) in Aqueous Matrix

In this research, the thin film microextraction method was applied for the extraction of Ni(II) ion from aqueous matrixes. Chemically modified cellulosic filter paper with phosphorus was used as a thin film extractor. After extraction, the thin film was treated with a solution of dimethylglyoxime. The colored film was captured by flatbed scanner and the absorbance of the images was extracted by some suitable software. Under the optimum conditions and at the pH 7.0, with the sample volume of 100 mL, the stirring rate of 800 rpm, and the extraction time of 50 min, the calibration curve was obtained in the range of 0.05–5 mg/L Ni(II) (R 2 = 0.989). Limit and relative standard deviation were achieved to be 18 µg/L and less than 6.7%, respectively. Relative recoveries were obtained in the range of 87%–105%. Finally, the proposed method was found to be simple and cost-effective, with adequate analytical performance for the rapid detection of Ni(II) in river and wastewater samples.