Accuracy and precision in the determination of perfluorinated chemicals in human blood verified by interlaboratory comparisons.

Perfluorinated chemicals (PFCs) are analyzed in laboratories worldwide to determine human blood levels and exposure pathways. The development of the analytical technique has been rapid in the last 10 years, and prerequisites for accurate and precise determination of PFCs in human blood at low ng/g concentrations are today readily available. The main contributing factors are the improved LC-MS instrumentations, the increased availability of native and mass labeled PFC standards, and new column materials available for chromatographic separations. The results of the first international interlaboratory study (ILS) in 2005 on PFCs revealed relatively better analytical results for human blood analyses when compared to analyses of a number of environmental matrices. The representative accuracy for the analyses of PFCs in human matrixes reported in recent years was established in the second human serum ILS in 2006. Interlaboratory standard deviations for the two human serum samples one low level concentration and one medium level concentration were found to be 12% and 16% for PFOS, respectively, and 47% and 21% for PFOA, respectively. Reported detections for all PFCs followed a frequency of PFOS>PFOA>PFHxS>PFNA>PFDA>>PFDoA>>PFDS>>PFHxA. Due to the small number of reported values for the other perfluorosulfonates and perfluorocarboxylates, standard deviations were not established.