Ultrasound-assisted solid phase extraction of nitro- and chloro-(phenols) using magnetic iron oxide nanoparticles and Aliquat 336 ionic liquid

• Efficient adsorption of nitro- and chloro-(phenols) using ALQ-MIONPs as adsorbent.
• The ultrasound assisted adsorption process is fast and takes about 10 min.
• High enrichment factors (76–195) obtained for pre-concentration of target analytes.
• Limits of detections (LODs) ranging from 0.005 to 0.041 μg L−1 were obtained.

A novel and sensitive ultrasound-assisted solid phase extraction (UASPE) method for pre-concentration and determination of ultra-trace amounts of nitrophenols and chlorophenols in water samples was demonstrated. Four hazardous phenolic compounds in water samples were extracted and monitored by high performance liquid chromatography. The results demonstrated that in the presence of Aliquat 336 (ALQ), magnetic iron oxide nanoparticles (MIONPs) were quite efficient in the adsorption and pre-concentration of traces of analytes. MIONPs were synthesized and characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The important parameters influencing the extraction efficiency were studied and optimized. The separation and pre-concentration steps were fast and completed in 10 min. Acetonitrile was used for the desorption of target analytes. Under optimum adsorption conditions, a linear range between 0.015 and 100 μg L−1 (R2 ≥ 0.997), and limits of detections (LODs) ranging from 0.005 to 0.041 μg L−1 were obtained. Enrichment factors in the range of 76–195 were achieved and relative standard deviations (%RSDs) were less than 10.0 (n = 3) for the target analytes. The analytical method was successfully applied for environmental water samples such as tap water and river water. The recoveries varied within the range of 70–119% confirming the good performance of the method in various water samples. The results showed that the proposed method is a rapid, convenient and feasible technique for the determination of nitrophenols and chlorophenols in aqueous samples.