Selenium and other elements in human maternal and umbilical serum, as determined simultaneously by proton-induced X-ray emission.

Using PIXE (proton-induced X-ray emission), we simultaneously determined the concentrations of Se, Ca, Fe, Cu, Zn, Br, and Pb in blood serum from 56 pregnant women, 25 healthy controls, and 31 others with twin pregnancy or some complicating condition (diabetes, hypertension, epilepsy, hepatosis gravidarum, pre-eclampsia, small baby), and in cord-blood serum from 21 newborns. Pellets, pressed from the serum samples after addition of yttrium as an internal standard, mixing, and evaporating at 30 degrees C with or without reduced pressure (less than 1 kPa), were bombarded by 2.2 MeV protons from a Van de Graaff accelerator in the air and the induced X-rays collected by a Ge(Li) detector. Relative to mean Se values for early six- to 12-week pregnancy (0.045 ppm), those for 35-42 week pregnancy (0.028 ppm) were low (p less than 0.001). Umbilical cord blood serum showed even lower values (0.016 ppm, p less than 0.001)--findings in harmony with the incidence pattern of Keshan cardiomyopathy. Pb crossed the placenta; values for cord serum were not significantly different from those in pregnancy serum. Cu, Zn, Fe, and Ca showed the significant expected patterns in the different groups. Compared with the late-pregnancy controls, Fe was high in mothers of small-birth-weight babies (1.70 ppm, p less than 0.02). Br was high in pre-eclampsia (3.59 ppm, p less than 0.05) and mothers with twins (3.61 ppm, p less than 0.05).