Analytical Sciences

Determination of Bisphenol A and 4-Nonylphenol in Human Milk Using Alkaline Digestion and Cleanup by Solid-Phase Extraction

Hiroaki OTAKA,*  Akio YASUHARA,** and Masatoshi MORITA**

*National Environmental Research and Training Institute, Ministry of the Environment, 3-3 Namiki, Tokorozawa, Saitama 359-0042, Japan
**National Institute for Environmental Studies, 16-9 Onogawa, Tsukuba, Ibaraki 305-8506, Japan

A highly sensitive and selective method based on alkaline digestion for the simultaneous determination of bisphenol A (BPA) and 4-nonylphenol (NP) was developed. The method consists of digestion of the matrix with ethanolic KOH, extraction with diethyl ether under a mild alkaline condition, cleaning with successive aminopropyl (NH₂) cartridges and derivatization followed by a GC-MS analysis. The assay accuracies, expressed as recoveries, were 82 - 113% for BPA and 89 - 97% for NP. The limits of detection of BPA and NP were 0.09 ng/g and 0.50 ng/g, respectively. The procedure will be reliable for the trace analysis of BPA and NP in human milk, since alkaline digestion can diminish their documented association with protein.

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