Determination of bisphenol A, 4‐octylphenol,and 4‐nonylphenol in soft drinks and dairy products by ultrasound‐assisted dispersive liquid–liquid microextraction combined with derivatization and high‐performance liquid chromatography with fluorescence detection

A novel hyphenated method based on ultrasound‐assisted dispersive liquid–liquid microextraction coupled to precolumn derivatization has been established for the simultaneous determination of bisphenol A, 4‐octylphenol, and 4‐nonylphenol by high‐performance liquid chromatography with fluorescence detection. Different parameters that influence microextraction and derivatization have been optimized. The quantitative linear range of analytes is 5.0–400.0 ng/L, and the correlation coefficients are more than 0.9998. Limits of detection for soft drinks and dairy products have been obtained in the range of 0.5–1.2 ng/kg and 0.01–0.04 μg/kg, respectively. Relative standard deviations of intra‐ and inter‐day precision for retention time and peak area are in the range of 0.47–2.31 and 2.76–8.79%, respectively. Accuracy is satisfactory in the range of 81.5–118.7%. Relative standard deviations of repeatability are in the range of 0.35–1.43 and 2.36–4.75% for retention time and peak area, respectively. Enrichment factors for bisphenol A, 4‐octylphenol, and 4‐nonylphenol are 170.5, 240.3, and 283.2, respectively. The results of recovery and matrix effect are in the range of 82.7–114.9 and 92.0–109.0%, respectively. The proposed method has been applied to the determination of bisphenol A, 4‐octylphenol, and 4‐nonylphenol in soft drinks and dairy products with much higher sensitivity than many other methods.