Quantitative investigations on the diaplacental transfer of thallium by field desorption mass spectrometry.

The placental transfer of thallium cations in pregnant mice was investigated by determining the thallium concentrations in fetal and maternal tissue 0.5 to 24 h after application of thallium. The maternal dose of thallium was 8 mg/kg body weight throughout. Uterus and fetus were found not to differ from other organs like heart and liver in time course and magnitude of thallium uptake with an initial surge during the first few hours of exposure to thallium and a rapid decrease to steady 12 and 24 h values somewhat lower than those found in the kidney. Diaplacental transfer is therefore assumed comparatively rapid and a specific placental barrier for thallium does not seem to exist. For the determination of thallium concentrations Field Desorption Mass Spectrometry was utilized as a reliable, fast and sensitive method for the analysis of metal cations in biological material. This method does not require extensive pretreatment of the tissue and total sample amounts in the range of milligrams and less are sufficient for quantitative analysis.