Density gradients for isolation of mononuclear blood cells for magnesium analysis by electron probe X-ray microanalysis.

We present a mononuclear blood cell (MBC) isolation method for magnesium analysis by electron probe X-ray microanalysis. We compare the inorganic elemental composition of individual MBC isolated by either arabinogalactan (Stractan) or conventional Ficoll-Hypaque density gradients. We find that the MBC isolated with Stractan have the expected cellular element composition, but MBC isolated with Ficoll-Hypaque are contaminated with iodine and sodium. We discuss the source and significance of iodine and sodium contamination of Ficoll-Hypaque isolated MBC and recommend the Stractan separation method for electron probe X-ray microanalysis.