Abstract
A simple and practical pre-concentration method, dispersive liquid-liquid microextraction based on solidification of a floating organic drop (DLLME-SFO) technique, was proposed for the determination of 4-nitrophenol and 2-nitrophenol in water samples. The effective experimental parameters on the extraction efficiency such as extraction solvent volume, dispersive solvent volume, and pH were studied using the response surface methodology. Under the optimum experimental conditions, the pre-concentration factors of 116 and 100 for 2-nitrophenol and 4-nitrophenol were obtained, respectively. The calibration curves were linear in the range of 5-150 µg L−1 with the detection limit of 1.70 µg L−1. The proposed method was successfully applied to the determination of nitrophenols in water samples.
Highlights
Nitrophenolic compounds are some of the most common pollutants in aquatic environments
Dispersive liquid-liquid microextraction (DLLME)-SFO combined with high performance liquid chromatography (HPLC) was used for simultaneous extraction and pre-concentration of two nitrophenols in water samples
The enrichment factor (EF) was defined as the ratio of the analyte concentration in the collected phase to the analyte concentration in the aqueous sample, where the analyte concentration in the collected phase was calculated from the direct calibration graph (0.1-5.0 mg L−1) of nitrophenols in methanol
Summary
Nitrophenolic compounds are some of the most common pollutants in aquatic environments. Regular SPE requires large volumes of toxic solvent, column conditioning and a process that is complicated and time-consuming.[17] SPME is solvent free, simple and fast, it is more expensive and its fibers are fragile It has a limited life time, and sample carry-over in this method can be a problem.[18,19] The main drawbacks of SDME include instability and volatility of the extraction solvent.[20] HF-LPME is simple and consumes a small amount of organic solvent, the extraction time needed in this technique is usually long.[21] the development of environmentally friendly pretreatment methods is necessary to overcome such disadvantages. The glass tube was transferred into the ice bath, and the solidified organic solvent was transferred into the conical vial where it melted quickly at room temperature and was injected into the HPLC system for analysis
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