Ultrasound-assisted extraction combined with reverse phase-dispersive liquid-liquid micro extraction as a new approach for preconcentration and spectrophotometric determination of total phenol in marine sediments of Chabahar Bay

•RP-DLLME have been successfully developed for the preconcentration of trace amounts of phenol from sediment samples.•In this procedure using an alkaline water instead of organic solvent leads to be an environmental friendly method.•This method enjoys advantages such as high recovery and very short time; it is also simple and inexpensive.•This technique will be applicable in a variety of solid samples in different fields.

In this study, Reverse phase dispersive liquid–liquid micro extraction (RP-DLLME) technique have been successfully developed to preconcentrate trace amount of phenol from sediment samples as a prior step to its derivatization with 4-aminoantipyrine and enhanced determination by UV–Vis spectrophotometry after primary ultrasonic extraction. In this procedure, 50 μL 0.7 M NaOH solution was chosen as extraction solvent and other factors including pH, extraction time, concentration of 4-aminoantipyrine, type and volume of dispersive solvents were optimized. Under selected conditions, the limit of detection, the linearity range, relative standard deviation and enrichment factor of method were obtained 15 μg·kg− 1, 50–1800 μg·kg− 1, 4.8% (n = 10) and 33, respectively. Finally, using the high sensitivity, low organic solvent consumption and waste generation method, total phenol content in marine sediments from several locations in Chabahar Bay (southeast Iran) was estimated at 55.8–73.2 μg·kg− 1.