Uncertainty Evaluation for the Determination of Perfluorinated Compounds in Wastewater Treatment Facility Effluent

This study evaluates the sources of uncertainty in the determination of poly & perfluorinated compounds(PFHxS, PFOS, PFOA) in the effluent of a wastewater treatment facility using LC-MS/MS. The uncertainty sources were identified and, numerically quantified, and the overall uncertainty of the final results was calculated through the synthesis and expansion of uncertainties. The main factors contributing to the combined standard uncertainty were identified as the construction of calibration curves, the reproducibility uncertainty from repeated tests, and the uncertainty associated with sample collection. By contrast, the effects of processes such as the volume filling of 1 mL standards after concentration and the injection of internal standards were found to be negligible. The relative expanded uncertainties for the three perfluorinated compounds were within 7.45%. The contributions to the overall uncertainty from sample collection, calibration curve construction, internal standard injection, volume filling of 1 mL standards, and reproducibility from repeat tests were 1.16~1.62%, 87.11~94.52%, 0.37~0.53%, 0.33~0.46%, 2.87~11.03%, respectively.