Ionic liquid for single-drop microextraction followed by high-performance liquid chromatography-ultraviolet detection to determine carbonyl compounds in environmental waters.

A sensitive method based on ionic liquid for single-drop liquid microextraction coupled with HPLC-UV was developed for the determination of carbonyl compounds in environmental waters using 1-octyl-3-methylimidazolium hexafluorophosphate [C(8)min][PF6] as extraction solvent and 2,4-dinitrophenylhydrazine as derivatizing agent. The extraction parameters affecting the enrichment factors such as solvent volume, pH, extraction time and salt concentration were investigated. A homemade funnel form polytetrafluoroethylene sleeve was fixed at the tip of the syringe needle and this allowed the use of 10 mu L drop of ionic liquid for direct immersion extraction. Under the optimal conditions, the remarkable enrichment factors up to 150-fold were obtained depending on the target analytes. The method has been validated when rectilinear relationship was obtained between the concentrations of analytes and peak area in the range of 5-100 ng/mL, the correlation coefficients were from 0.995 to 0.998, and the limit of detection was in the range of 0.04-2.03 ng/mL. The method was applied to monitor the concentration of carbonyl compounds in environmental waters with spiked recovery in the range of 84.2-106.9%.