Trace element analysis of human seminal plasma: A cautionary tale of preanalytical variation and use of non-traditional matrices in human biomonitoring studies.

Ensuring harmonization of (ultra-)trace element measurements in non-traditional matrices is a particular analytical challenge that is highlighted in this work for seminal plasma as part of the developmental core at the Wadsworth Center Human Health Exposure Analysis Resource Targeted Laboratory. Seminal plasma was collected from 39 male partners of women undergoing in vitro fertilization and analyzed by inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) following deproteinization with concentrated HNO3. Validation was accomplished using: 1) two aqueous NIST SRMs; 2) a seminal plasma QC pool, characterized via standard additions; 3) standard additions on a subset of samples; and 4) sample duplicates. Agreement with NIST certified or reference values were obtained to within ±15% for the SRMs, and agreement between aqueous calibration values and standard additions values agreed to within ±10-20% for all elements. Standard additions of seminal plasma samples revealed varying matrix effects for Cu and Cr that were not found for the pooled samples. Duplicate analyses agreed to within ±10-30% depending on element. A potential source of contamination in colloidal silica used for processing seminal plasma was identified that requires further study. Comparisons with literature indicate lack of consensus for As, Cd, Cr, Mn, Pb, and V content in seminal plasma. Further work is needed to improve harmonization of future studies.