Uncertainty Evaluation of Content Determination of Sulfur Dioxide in Angelicae Dahuricae Radix by Acid-Base Titration
Objective To establish an evaluation method for the uncertainty of content determination of sulfur dioxide in Angelicae Dahuricae Radix by the acid-base titration method.Methods Based on the Chinese Pharmacopoeia(2020 Edition,Volume Ⅳ),the content of sulfur dioxide in Angelicae Dahuricae Radix was determined by the acid-base titration method,the calculation formula was determined,and the uncertainty introduced during the experimental process was analyzed and evaluated.Results The uncertainty of synthetic standard was 0.427%.The parallel determination of sulfur dioxide residue in Angelicae Dahuricae Radix was 92.3 mg/kg and 91.8 mg/kg,respectively.When the confidence level was 95%and the inclusion factor k was 2,the true sulfur dioxide residue in Angelicae Dahuricae Radix was(92.0±0.6)mg/kg.Conclusion The uncertainty of content determination is mainly introduced by the sample titration process,followed by the weighing of the reference substance,pipette and burette.