Polybrominated diphenyl ethers (PBDEs): A series of PBDEs will be measured at trace levels (ng/g lipid weight) in breast milk provided by volunteers.
Breastmilk collection: Participants will provide breastmilk samples (100 ml ideally) within chemically clean, 120 ml foil-wrapped glass jars, prepared by the University of Arizona (UA) or certified by the UA to be free of target chemicals within the sensitivity of the methods applied. Several collection sessions may be required to fill each jar. The samples will then be refrigerated and frozen when collection is completed (volume met). Participants are advised to minimize skin contact with the jar (lip and lid) and to minimize the possibility of contamination by skin, hair, or dust. Once received by the UA, samples will be stored at -20ºC until analysis.
Polybrominated diphenyl ether analysis: The analytical approached follows methods successfully applied by the State of California and the US Centers for Disease Control and Prevention (CDC). The UA team is currently conducting research using Enhanced Matrix Removal (EMR) protocols that have been specifically developed to allow for lipid removal without loss of analyses and have been applied numerous times for analysis of trace organic chemicals in milk. In general, the EMR tubes contain a mixture of solid-phase extraction (SPE) sorbents and MgSO4, that will absorb the matrix material and excess water. Our team will only apply EMR upon successful performance evaluation that demonstrates equivalency, or better, to previously published work using the method
Instrumental analysis will be performed using gas chromatography (GC) with mass spectrometric detection (GC-MS). PBDEs will be separated using a DB-5MS column (15 m x 0.25 mm I.D. x 0.1um film thickness, Agilent J&W, USA).