Development of a sensitive method for the determination of parabens in complex samples by online coupling of magnetism-enhanced monolith-based in-tube solid phase microextraction with high performance liquid chromatography

Abstract

Due to their adverse impacts on humans, sensitive monitoring of parabens in real-life waters and beverages is necessary and interesting. In this work, a simple, rapid and sensitive analytical method for the determination of parabens in environmental waters and grape juices was established by on-line coupling of magnetism-enhanced monolith-based in-tube solid-phase microextraction (ME-MB/IT-SPME) with high performance liquid chromatography equipped with a diode array detector (HPLC-DAD). A series of key parameters affecting the extraction efficiency, including the intensity of the magnetic field, the sampling rate and desorption flow rate, the volume of the sample and desorption solvent, the pH value and ionic strength of the sample matrix, were investigated in detail. Under the most favorable conditions, satisfactory extraction efficiencies ranging from 81.2% to 88.2% for target parabens were achieved. At the same time, the proposed method showed satisfactory sensitivity and the limits of detection (S/N = 3) obtained in water and grape juice samples were in the ranges of 0.010–0.026 μg L⁻¹ and 0.019–0.051 μg L⁻¹, respectively. Excellent method reproducibility was found based on intra-day and inter-day precisions, with relative standard deviations (RSDs) lower than 9%. The practicability of the proposed ME-MB/IT-SPME-HPLC-DAD method was demonstrated by successfully applying it to the analysis of parabens in lake water, river water and grape juice samples with recoveries between 86.9% and 114%, and the RSDs were within 10%. The results indicated that the developed method was accurate, sensitive, practical and eco-friendly for the monitoring of parabens in both real-life waters and grape juices.