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

Exposure to hexavalent chromium (Cr VI) causes cancer in cells of the human body. So, the speciation and determination of the Cr (VI) and Cr (III) in water and human samples based on sensitive techniques are necessary. 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 stirringfor 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 mixture of the HS-CH3-IM was collected at the bottom of the conical tube by centrifuging. The upper liquid phase was vacuumed with a peristaltic pump and 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 after dilution up to 0.5 mL with DW. 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). The procedure was validated by spiking samples and good accuracy and precision results were achieved.