A sensitive method for the extraction and determination of polycyclic aromatic hydrocarbons (PAHs) using alcoholic-assisted dispersive liquid-liquid microextraction (AA-DLLME) and HPLC was developed. The extraction procedure was based on alcoholic solvents for both extraction and dispersive solvents. The effective parameters (type and volume of extraction and dispersive solvents, amount of salt and stirring time) on the extraction recovery were studied and optimized utilizing factorial design (FD) and central composite design (CCD). The best recovery was achieved by FD using 2-ethyl-1-hexanol as the extraction solvent and methanol as the dispersive solvent. The results showed that volume of dispersive solvent and stirring time had no effect on the recovery of PAHs. The optimized conditions were 145 μL of 2-ethyl-1-hexanol as the extraction solvent and 4.2% w/v of salt (NaCl) in sample solution. The enrichment factors of PAHs were in the range of 310-325 with limits of detection of 0.002-0.8 ng/mL. The linearity was 0.01-800 ng/mL for different PAHs. The relative standard deviation (RSD) for intra- and inter-day of extraction of PAHs were in the range of 1.7-7.0 and 5.6-7.3, respectively, for five measurements. The method was also successfully applied for the determination of PAHs in environmental water samples.
Summary. Alcoholic-assisted dispersive liquid-liquid microextraction method (AA-DLLME) is used for the extraction, purification, and determination of bisphenol A in water samples by HPLC-UV. 1-octanol and methanol were selected as extraction and dispersive solvents of AA-DLLME procedure. The effects of several parameters of the AA-DLLME procedure (such as volume of extraction and dispersive solvents, amount of salt in sample solution, and extraction time) were investigated by a full factorial design. Then, the levels of significant factors were optimized using a central composite facecentered. The optimum conditions were obtained at 158 μL of extraction solvent, 500 μL of dispersive solvent, 1 min extraction time, and addition of 22% (w/v) of NaCl to the sample solution. Under optimum condition, the extraction recovery and the enrichment factor were determined, which were 91% and 65%, respectively. At these conditions, the limit of detection and the linearity were 0.10 and 1-100 μg L −1 , respectively. The relative standard deviations for intra-and inter-day of extraction of bisphenol A (BPA) were 6.98% and 9.80%, respectively (for five measurements). Finally, the method was successfully applied for the determination of BPA in environmental water samples. In conclusion, it can be stated that the applied method is fast, simple, and environmentally friendly.
Optimization of alcoholic-assisted dispersive liquid-liquid microextraction of pentachlorophenol (PCP) and determination of it with high-performance liquid chromatography (UV-Vis detection) was investigated. A Plackett-Burman design and a central composite design were applied to evaluate the alcoholic-assisted dispersive liquid-liquid microextraction procedure. The effect of seven parameters on extraction efficiency was investigated. The factor studied were type and volume of extraction and dispersive solvents, amount of salt, and agitation time. According to Plackett-Burman design results, the effective parameters were type and volume of extraction solvent and agitation time. Next, a central composite design was applied to obtain optimal condition. The optimized conditions were obtained at 170-μL 1-octanol and 5-min agitation time. The enrichment factor of PCP was 242 with limits of detection of 0.04 μg L(-1). The linearity was 0.1-100 μg L(-1) and the extraction recovery was 92.7%. RSD for intra and inter day of extraction of PCP were 4.2% and 7.8%, respectively for five measurements. The developed method was successfully applied for the determination of PCP in environmental water samples.
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