Objective To establish a spectrophotometric evaluationmethod for determining sulfur dioxide uncertainty in formaldehydeabsorption fluid. Methods According to JJF 1059-2012, Evaluation andrepresentation of measurement Uncertainty, establish a mathematicalmodel to calculate each uncertainty component and synthetic uncertainty. Results The uncertainty introduced by repeated measurement is 0.27%; thestandard curve preparation is 0.40%; the standard curve drawing andfitting is 0.20%; the instrument measurement is 0.35%; the syntheticrelative standard uncertainty is 0.63%, and the extended uncertainty is ${0.008}\mathrm{{mg}}/\mathrm{L}$ . Conclusion This method is suitable for measuring the uncertaintyassessment of sulfur dioxide in formaldehyde absorption fluid.

spectrophotometric method  /  sulfur dioxide  /  uncertainty