Green thin-film microextraction based on polyaniline emeraldine salt-coated cellulose filter paper as an efficient preparation plane for extraction of Cd from environmental samples

Herein, a convenient, low-cost, and environmentally friendly sorbent based on biopolymer was fabricated and applied for thin-film microextraction (TFME) of cadmium ions from various matrices. The biodegradable cellulose-based filter paper was coated with polyaniline emeraldine salt. The sorbent surface properties were studied by Fourier transform infrared spectroscopy and scanning electron microscopy. The positively charged modified filter paper was utilized as the sorbent in TFME for separation and preconcentration of the anionic complex of cadmium ion (CdI42−). The analyte was then eluted from the sorbent by 0.5 mL of sodium hydroxide (0.5 mol L−1) and determined by flame atomic absorption spectrometry. The extraction conditions including pH, sorption and desorption time, sample volume, and desorption parameters were considered and optimized. At optimum conditions, the method has a linear range of 0.25–25 µg L−1, a limit of detection of 0.06 µg L−1, and an enhancement factor of 198. The method precision values which were calculated as relative standard deviation (RSD%), at 3 µg L−1 cadmium solution were 3.4 (intra-day) and 4.7% (inter-day). The proposed method was successfully applied to the enrichment and trace levels determination of cadmium ions in various environmental water samples.