OBJECTIVETo evaluate the uncertainty of measurement result of urinary fluoride and to provide quality assurance for determinations.

METHODThe investigation was conducted, according with principles and methods for uncertainty evaluation.

RESULTSThe uncertainty of the combined standard of present method was 2.86 %. For the sample containing 4.47 mg/L urinary fluoride, the expanded uncertainty was 0.26 mg/L.

CONCLUSIONThe uncertainty of the present method was mainly from the sample repeatability, the preparation of standard solution, the linearity of the calibration curve and instruments and so on.