Lanthanide distribution in human placental tissue by membrane desolvation-ICP-MS

Abstract

Lanthanide elements are finding increasing use in industrial, technological, and medical applications, due to their unique magnetic, optic, and catalytic properties. Consequently, the risk of human exposure to these nonessential elements is rising, and the ability to measure the lanthanides in human tissues and body fluids is gaining in importance. In this study, the concentrations of naturally occurring lanthanide elements, as well as Sc, were measured in human placental tissues, consisting of ∼160 samples each of placenta body, membrane, and umbilical cord, for evaluation of possible maternal and fetal exposure to these metals. Measurements were conducted using ICP-MS instrumentation coupled to a membrane desolvation introduction system, in order to enhance sensitivity for these elements, as well as to decrease oxide formation. Method detection limits (MDLs) ranged from 0.3 ng g⁻¹ to 4 ng g⁻¹. Method validation entailed the use of a mussel tissue reference material (RM) certified for most of the analytes of interest, spike recovery experiments and, for some analytes, a caprine liver secondary RM. Heavier lanthanides (Eu–Lu) were not detectable in most placental tissues. Lighter lanthanides (La–Sm) were detected in the ng g⁻¹ range. The placenta body accumulated the greatest concentrations of lanthanides. Lanthanide concentrations in placenta appeared to follow a pattern similar to that found in the Earth's crust, indicating natural human exposure to these analytes.