Rapid analysis of chromium (III, VI) in water and wastewater samples based on Task-specific ionic liquid by the ultra-assisted dispersive ionic liquid-liquid microextraction

 In this research, 2-mercapto-1-methylimidazole a novel Task-specific ionic liquid (C4H6N2S; HS-CH3-IM) was used with a new approach for speciation of Cr (III, VI) from water samples by ultra-assisted dispersive ionic liquid-liquid microextraction procedure (USA-D-ILLME). Due to the procedure, 100 mg of HS-CH3-IM and 0.2 mL of acetone were mixed and injected into 10 mL of water or standard Cr (III) and Cr (VI) solution in the conical tube. After stirring for 5 min, the Cr (VI) and Cr (III) were extracted with a positive and negative charge of the thiol group (HS2+, HS-) in pH 2 or 8 and pH 5, respectively. The  Cr (III, VI) loaded on the HS-CH3-IM was back-extracted in a liquid solution. Finally, the concentration of the Cr (III, VI) ions in a remained solution were measured with ET-AAS . The total chromium was determined in water samples by summarizing the Cr (VI) and Cr (III) contents. All parameters such as the amount of HS-CH3-IM, the sample volume, pH, and the shaking/centrifuging time were optimized. Under the optimal conditions, good linear range (LR), LOD, and enrichment factor (EF) were obtained 0.05–1.7 μg L−1, 15 ng L−1, and 19.82 respectively (RSD% < 1.45).