Development of a New Method for the Determination of Manganese, Cadmium, Mercury and Lead in Whole Blood and Amniotic Fluid by Inductively Coupled Plasma Mass Spectrometry

Environmental exposure to metals among women, revealed their adverse effects on pregnancy. During this stage, blood levels of some metals increase so research on heavy metals transference from the mother's blood to the developing foetus is of special interest and much attention has been paid to this matter. The amniotic fluid can be considered as a valuable marker of this prenatal exposure to exogenous factors. The aim of this study was to develop a method for the simultaneous determination of Mn, Cd, Hg, and Pb in whole maternal blood and amniotic fluid by ICP-MS. Strategies were given to minimise memory effects related to mercury and two widespread digestion procedures (open-vessel and microwave-assisted) were compared. Several quality controls, such as methodological and reagent blanks, spiked samples and duplicates were used to test the goodness of the developed method. Once optimised, the method was applied for the monitoring of Mn, Cd, Hg and Pb in 15 maternal blood and amniotic fluid samples obtained at delivery after informed consent. This study establishes that heavy metals pass into and accumulate in amniotic fluid and maternal blood. Thus, mean concentrations of Mn were similar in the two biological fluids studied, 21.6 ng/mL in maternal blood and 20.5 ng/mL in amniotic fluid. Mean Cd and mercury levels in blood and amniotic fluid were 1.3 and 6.3 ng/mL and 3.4 and 3.8 ng/mL, respectively. Concentrations of Pb were 16.4 ng/mL in blood and 13.7 ng/mL in amniotic fluid. Further studies are needed to evaluate the long-term health effects derived from this exposure.