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EN
Abstract An efficient method based on dispersive liquid-liquid microextraction coupled with micellar electrokinetic chromatography has been developed for determination of three phenoxyacid herbicides (PAs) of 2,4-dichlorophenoxybutyric acid (2,4-DB), dicamba and 2,4-dichlorophenoxyacetic acid (2,4-D), in environmental water samples. The types and volumes of extracting and dispersing solvents, ionic strength, extraction and centrifugation time and centrifugation speed were investigated. Successful separation of the three PAs was achieved within 7 min, by using the background electrolyte solution consisting of 10 mmol L−1 sodium tetraborate, 25 mmol L−1 sodium dodecyl sulfate and 15% (v/v) methanol, at pH 9.75. Excellent analytical performances were attained, such as good linear relationships (R ≥0.9993) between peak area and concentration for each PAs from 10–1000 ng mL−1, limits of detection of 1.56–1.91 ng mL−1, and intra-day precisions at two spiked levels in terms of migration time and peak area within the range of 0.22–0.42% and 3.88–6.39%, respectively. Enrichment factors of 2,4-DB, dicamba and 2,4-D were 180, 151 and 216, respectively. The method recoveries obtained at fortified 20.0, 50.0 and 100.0 ng mL−1 for lake, river and reservoir water samples varied from 67.91 to 119.07% with the relative standard deviation of 1.47–6.89%. Graphical abstract [...]
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Ionic liquids in microextraction techniques

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EN
The tremendous potential of room temperature ionic liquids as an alternative to environmentally harmful ordinary organic solvents is well recognized. Due to their unique properties, such as low volatility, tunable viscosity and miscibility, and electrolytic conductivity, ionic liquids have attracted extensive attention and gained popularity in many areas of analytical chemistry including modern sample preparation techniques. In this review the advantages and limitations of application of ionic liquids as solvents/sorbents for microextraction are critically discussed. Topics covered include solid-phase microextraction, single drop microextraction, dispersive liquid-liquid microextraction and hollow-fiber liquid-phase microextraction. The compatibility of the ionic liquid-based microextraction with different analytical techniques such as gas chromatography, high-performance liquid chromatography, electrothermal or flame atomic absorption spectrometry and some others is also discussed. Finally, the main practical applications on this topic are summarized. [...]
EN
A simple and sensitive dispersive liquid-liquid microextraction method for extraction and preconcentration of pentachlorophenol (PCP) in water samples is presented. After adjusting the sample pH to 3, extraction was performed in the presence of 1% W/V sodium chloride by injecting 1 mL acetone as disperser solvent containing 15 μL tetrachloroethylene as extraction solvent. The proposed DLLME method was followed by HPLC-DAD for determination of PCP. It has good linearity (0.994) with wide linear dynamic range (0.1–1000 μg L−1) and low detection limit (0.03 μg L−1), which makes it suitable for determination of PCP in water samples. [...]
EN
A small-scale, simple, and rapid dispersive liquid-liquid microextraction (DLLME) procedure in combination with fiber optic-linear array detection spectrophotometry (FO-LADS) with charge-coupled device (CCD) detector has been developed, with benefits from the use of a micro-cell. The official reference methods (ASTM D2330 - 02, ISO 7875-1), which require tedious procedures, were replaced with a modified method. The new method provides a major reduction in sample size, elimination of the use of expensive glassware, and a decrease in the quantity of chloroform used, as well as increased sensitivity. Our method requires only one twentieth of the sample (5.0 mL), and less than one three-hundredth of microextraction solvent (chloroform = 138 µL). It provides a faster analysis time than official analytical methods (less than one minute). The calibration curve was linear in the range of 6–80 µg g L−1 of sodium dodecyl sulfate (SDS) with a correlation coefficient (r) of better than 0.99 and the LOD was 2 µg L−1. The repeatability of the proposed method (n=7) was found to be 4.5% and 3.6% for the concentrations of 0.03 and 0.07 mg L−1, respectively. The enrichment factor was found to be 75 for SDS. [...]
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