Magnetic multi-walled carbon nanotubes as a solid phase extraction adsorbent for the determination of 13 phthalate acid esters in water samples by gas chromatography-mass spectrometry

A method based on solid phase extraction (SPE) with magnetic multi-walled carbon nanotubes (MWCNTs) as adsorbent was developed for the determination of 13 phthalate acid esters (PAEs) in water samples by gas chromatography-mass spectrometry (GC-MS). The factors affecting the extraction efficiency, such as extraction time, pH of water sample, desorption solvent, and desorption time, were carefully investigated. The optimized conditions were as follows: extraction time, 10 min; pH of water samples, 5 - 7; desorption solvent, 2 mL acetone; desorption time, 5 min. The extraction efficiencies were 89.7% - 100.5% under the optimized conditions. The method was sensitive with the detection limits (S/N = 3) between 0.08 - 0.47 mu g/L for the 13 PAEs. The developed method was successfully applied for the analysis of tap water, bottle drinking water and lake water, and none of the 13 PAEs was detected. The recoveries ranged from 84.5% to 107.5% for the 3 real spiked samples, and the relative standard deviations were between 1.9% and 12.8%. The developed method has proved convenient, time-saving, accurate, sensitive, and environmental-friendly, and can be used for the determination of PAEs in water samples.