No abstract

A new method based on ionic liquid cold-induced aggregation microextraction (IL-CIAME) in combination with fiber optic-linear array detection spectrophotometry (FO-LADS) has been developed for the analysis of crystal violet (CV) in saline samples. In this methodology, a suitable temperature is used to fully dissolve very small amounts of 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF 6 ] and 1-hexyl-3methylimidazolium bis(trifluoromethylsulfonyl)imide [Hmim][Tf 2 N] as hydrophobic ionic liquids (ILs) and extractant solvents in the sample solution without the use of a disperser solvent. After dissolving, the solution was cooled in an ice bath and a cloudy solution of IL fine droplets was formed due to the decrease of IL solubility. After centrifuging, the fine droplets of the extractant phase settled to the bottom of the conical-bottom centrifuge tube. In this method, which is robust against high content of salt and water-miscible organic solvents, various parameters were investigated and optimized. Under the optimum conditions, the limit of detection (LOD) of the method was 1.16 mg L À1 and the relative standard deviation (RSD) for 20 mg L À1 CV was 2.30%. The obtained results indicated that the developed method is an excellent alternative for routine analysis in the environmental field.

We report on a simple, rapid and efficient extraction procedure, referred to as ultrasound-assisted cold-induced aggregation (USA-CIAME), for the extraction of phenol from aqueous samples. In this method, very small amounts of the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate (the extractant) are dissolved in a sample solution containing phenol and ultrasonicated for 1 min. The solution is cooled in an ice bath upon which a cloudy solution forms. Following centrifugation, the extractant phase settles at the bottom of a conical-bottom centrifuge tube. Phenol is photometrically determined after its chromogenic reaction with 4-aminoantipyrine in the presences of hexacyanoferrate at pH 10.0. Compared to the conventional cold-induced aggregation microextraction (CIAME) and dispersive liquid liquid microextraction (DLLME), the optimized approach displays the highest extraction efficiency at room temperature, and the shortest extraction time (5 min). Key parameters affecting the performance were evaluated and optimized. Under optimum conditions, the limit of detection of phenol is 0.86 μg L −1 , and the enrichment factor is 75. The calibration graph as linear over the range from 3 to 150 μg L −1 , and the relative standard deviation is 2.65% (n05). The method was successfully applied to the determination of phenol in water samples.