Ultrasound-assisted dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry for determination of parabens in human breast tumor and peripheral adipose tissue

An efficient method for the determination of eight parabens in human breast tumor (n = 102) and peripheral adipose tissue samples (n = 87) was successfully developed. After a precipitation procedure (acetonitrile-water-15% (w/v) zinc sulfate solution) was applied to finely-chopped tissue samples, ultrasound-assisted dispersive liquid-liquid microextraction was conducted on the sample solution. The extracted parabens were determined by gas chromatography-mass spectrometry. Significant factors influencing extraction efficiency were screened and optimized using Plackett-Burman design and central composite design. The optimized conditions were obtained at 93 μL 1‑decanol, 500 μL methanol, and ultrasound irradiation power 156 W for 44 s. Under the optimum condition, the proposed method showed enrichment factors between 44.9 and 60.5. The detection limits for parabens were between 0.5 and 1.0 ng g−1. Calibration curves showed good linearity with coefficients of determination higher than 0.993. Relative standard deviations were lower than 11.8%. No significant matrix effects were observed as recoveries from spiked tissue samples ranged between 79.6% and 113.6%. The sample pretreatment procedure and analytical characteristics showed comparable or superior to those of the previously reported methods. Finally, the procedure was successfully employed in real samples and results indicated a wide existence of parabens in the tested tissues. At least one paraben was detected in 98.9% tissues and the levels ranged from 0.5 to 5931.1 ng g−1, depending on the types of analytes and tissues.