title: Automated solid phase extraction and quantitative analysis of human milk for 13 phthalate metabolites.
abstract: While the demonstrated benefits associated with breastfeeding are well recognized, breast milk is one possible route of exposure to environmental chemicals, including phthalates, by breastfeeding infants. Because of the potential health impact of phthalates to nursing children, determining whether phthalates are present in breast milk is important. We developed a sensitive method for measuring 13 phthalate metabolites in breast milk using automated solid phase extraction (SPE) coupled to isotope dilution-high-performance liquid chromatography (HPLC)-negative ion electrospray ionization-tandem mass spectrometry. We used D(4)-phthalate diesters to unequivocally establish the presence in human breast milk of enzymes capable of hydrolyzing the ubiquitous phthalate diesters to their respective monoesters. The analytical method involves acid-denaturation of the enzymes after collection of the milk to avoid hydrolysis of contaminant phthalate diesters introduced during sampling, storage, and analysis. The method shows good reproducibility (average coefficient of variations range between 4 and 27%) and accuracy (spiked recoveries are approximately 100%). The detection limits are in the low ng/ml range in 1ml of breast milk. We detected several phthalate metabolites in pooled human breast milk samples, suggesting that phthalates can be incorporated into breast milk and transferred to the nursing child.
authors.affiliation: Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA. acalafat@cdc.gov
authors.forename: Antonia M
authors.initials: AM
authors.lastname: Calafat
authors.forename: A Ryan
authors.initials: AR
authors.lastname: Slakman
authors.forename: Manori J
authors.initials: MJ
authors.lastname: Silva
authors.forename: Arnetra R
authors.initials: AR
authors.lastname: Herbert
authors.forename: Larry L
authors.initials: LL
authors.lastname: Needham
mesh_terms: D002851:Chromatography, High Pressure Liquid; D006801:Humans; D008895:Milk, Human / Q000737:chemistry*; D010795:Phthalic Acids / Q000032:analysis*; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D010795:Phthalic Acids