Concentrations of selected trace elements in human milk and in infant formulas determined by magnetic sector field inductively coupled plasma-mass spectrometry

Magnetic sector field inductively coupled plasma-mass spectrometry (ICP-MS) was applied to the reliable determination of the 8 essential trace elements cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), selenium (Se), and vanadium (V) as well as the 7 nonessential and toxic elements silver (Ag), aluminum (Al), arsenic (As), gold (Au), platinum (Pt), scandium (Sc), and titanum (Ti) in 27 transitory and mature human milk samples and in 4 selected infant formulas. This advanced instrumentation can separate spectral overlaps from the analyte signal hampering significantly the determination of many trace elements by conventional ICP-MS. Moreover, superior detection limits in the picogram per Liter range can be obtained with such magnetic sector field instruments. Therefore, this is the first study to report the concentrations of the elements Ag, Au, Pt, Se, Ti, and V in human milk and in infant formulas. Concentrations of Ag (median: 0.41 mu g/L; range: < 0.13-42 mu g/L) and Au (median: 0.29 mu g/L; range 0.10-2.06 mu g/L) showed large variations in human milk that might be associated with dental fillings and jewelry. Pt concentrations were very low with most of the samples below the method detection limit of 0.01 mu g/L. Human milk concentrations of Co (median: 0.19 mu g/L), Fe (380 mu g /L), Mn (6.3 mu g/L), Ni (0.79 mu g/L), and Se (17 mu g/L) were at the low end of the corresponding reference ranges. Concentrations of Cr (24.3 mu g/L) in human milk were five times higher than the high end of the reference range. For Al (67 mu g/L), As (6.7 mu g/L), and V (0.18 mu g/L), most of the samples had concentrations well within the reference ranges. All elemental concentrations in infant formulas (except for Cr) were approximately one order of magnitude higher than in human milk.