Determination of phthalate esters in bottled beverages by direct immersion solid-phase microextraction with a porous boron nitride coated fiber followed by gas chromatography-mass spectrometry

A porous boron nitride with a large surface area was synthesized by a one-step grinding method with melamine, urea, and boric acid as the precursors. The prepared porous boron nitride was used as the fiber coating material for the solid-phase microextraction of seven phthalate esters (diethyl phthalate, diallyl phthalate, diisobutyl phthalate, dibutyl phthalate, butylbenzyl phthalate, dicyclohexyl phthalate, and di-2-ethylhexyl phthalate) prior to their gas chromatography-mass spectrometric detection. The important experimental parameters including the extraction time, extraction temperature, salt concentration, and stirring rate were optimized by both single factor and central composite design methods. Under the optimized experimental conditions, the linear response range for the analytes was from 0.030 to 30.0 mu g/L, and the limits of detection were from 0.010 to 0.040 mu g/L, respectively. The relative recoveries of the analytes for spiked samples at two concentration levels were 83.0-109% with the relative standard deviations less than 12%. The established method was successfully applied for the determination of the phthalate esters in bottled juice beverage samples.