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.