Determination of benzophenone-UV filters in human milk samples using ultrasound-assisted extraction and clean-up with dispersive sorbents followed by UHPLC–MS/MS analysis

•The analysis of benzophenone UV-filters in human milk samples is validated.•An ultrasound-assited extraction procedure followed by a clean-up step is proposed.•Box–Behnken experimental design is used for the optimization of the different variables.•UHPLC–MS/MS is used as analytical technique to measure the target compounds.•After validation, the method has been applied in real human milk samples.

A new sample preparation method for the determination of five benzophenone UV-filters in human breast milk has been developed. The procedure involves the lyophilization of the sample, and its subsequent extraction by ultrasound sonication using acetonitrile. In order to reduce matrix effects produced by milk components that are coextracted, mainly proteins, sugars and lipids, a further clean-up step with a mixture of dispersive-SPE sorbents, C18 and PSA, was applied. Extraction parameters were optimized using experimental design, and the compounds were detected and quantified by ultrahigh performance liquid–chromatography tandem mass spectrometry (UHPLC–MS/MS) in positive ESI mode. Analytes were separated in 10 min. BP-d10 was used as internal standard. The limits of detection (LODs) were between 0.1 and 0.2 ng mL−1, and the limits of quantification (LOQs) were between 0.3 and 0.6 ng mL−1 for the target analytes. The inter- and intra-day variability was <12%. The method was validated using matrix-matched calibration and recovery assays with spiked samples. Recovery rates were between 90.9 and 109.5%. The method was successfully applied for the determination of these compounds in human milk samples collected from volunteers lactating mothers with no known occupational exposure to these compounds who live in the province of Granada (Spain). The analytical method developed here may be useful for the development of more in-depth studies on the prenatal exposure and biomonitoring of these commonly used UV-filters.

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