Determination of bisphenol A in human breast milk by HPLC with column‐switching and fluorescence detection

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Abstract
A highly sensitive HPLC method was developed for the determination of xenoestrogenic compound, bisphenol A (BPA) in human breast milk samples. After a two‐step liquid–liquid extraction, BPA was derivatized with fluorescent labeling reagent, 4‐(4,5‐diphenyl‐1H‐imidazol‐2‐yl)benzoyl chloride (DIB‐Cl). The excess fluorescent reagent could be removed effectively using a column‐switching system. The separation of DIB‐BPA from endogenous materials in milk was carried out on two C18 columns and fluorescence intensity was monitored at 475 nm with the excitation of 350 nm. A good linearity (r = 0.994) was observed of BPA in the concentration range of 0.2–5.0 ng mL−1 in breast milk, and the detection limit was 0.11 ng mL−1 at a signal‐to‐noise ratio of 3. Intra‐ and inter‐day precision (RSD, %) were less than 8.7 and 10.4, respectively. Twenty‐three breast milk samples of healthy lactating women were analyzed for the BPA concentration; the mean value was 0.61 ± 0.20 ng mL−1, with no correlation to the lipid content of milk samples. Copyright © 2004 John Wiley & Sons, Ltd.