目的  通过应用低浓度对照品，对定量伤寒Vi多糖疫苗O-乙酰基含量的药典方法（O-乙酰基测定法）进行改良，并验证该法的可行性。方法  以含0.05、0.10、0.20、0.30、0.40、0.50 μmol溴化乙酰胆碱的对照品溶液制作改良O-乙酰基测定法的标准曲线，并对该法的标准曲线线性、准确度、精密度、专属性和耐用性进行验证。结果  改良O-乙酰基测定法的标准曲线线性良好，决定系数>0.998。该法的准确度、精密度和专属性良好，O-乙酰基回收率为99.8%～101.3%，实验间和实验内相对标准偏差均<4%，O-乙酰基加样回收率均>96%。该法测定O-乙酰基的定量限为0.070 mmol/L。结论  应用低浓度对照品的改良O-乙酰基测定法可用于定量伤寒Vi多糖疫苗O-乙酰基含量。

Objective  To modify pharmacopoeia method (O-acetyl group assay) for quantitive detection of O-acetyl group content in typhoid Vi polysaccharide vaccine by using low concentration control, and validate the feasibility of the improved method. Methods  The standard curve of the improved method was established using control solution containing 0.05, 0.10, 0.20, 0.30, 0.40, 0.50 μmol of acetylcholine bromide, and the standard curve linearity, accuracy, precision, specificity and durability of the improved method were validated. Results  The standard curve linearity of improved method was good, with coefficient of determination was >0.998. The accuracy, precision and specificity were all good, the recoveries of O-acetyl group were 99.8%-101.3%, the relative standard deviation of intra- and inter-assay were both < 4%, the recoveries of O-acetyl group were all >96%. The limit of quantitation of O-acetyl group was 0.070 mmol/L. Conclusion  The modified method using low concentration control can be used for quantitative detection of  O-acetyl group content in typhoid Vi polysaccharide vaccine.