高精度散射光度滴定法

目的建立高精度散射光度滴定法, 并将此方法应用于药物分析。方法利用内置散射光传感器检测滴定溶液中的散射光相对强度的峰值来判断滴定终点。以AgNO3溶液滴定NaCl溶液为例验证了高精度散射光度滴定法, 并以AgNO₃溶液滴定苯妥英钠溶液和NaOH溶液滴定盐酸普鲁卡因溶液为例验证了该方法在药物分析中的适用性。结果此法可适用于低浓度测定。在适当的条件下高精度散射光度滴定法的精密度和准确度均在0.2%以内。结论此法可应用于药物分析。

Highly-accurate nephelometric titrimetry

Aim To indicate the titration end-point of precipitation reaction by measuring the relative intensity of the scattered light in the titrate for use in pharmaceutical analysis. Methods A visible light-emitting diode (LED) was used as a light source and a photodiode was used as the optical detector. Light on the detector creates an electric current through the diode. With the addition of the titrant, the titrate became turbid and the intensity of the scattered light in the solution increased gradually. If the precipitation reaction proceeded the completion and the solubility of the precipitate was small enough, the intensity of the scattered light will reach maximum at the stoichiometric point; thus, the titration end-point can be indicated. The accuracy of nephelometric titrimetry was discussed theoretically and the titration of NaCl with AgNO_3 was used as a model. To demonstrate the applicability of the new titrimetry in pharmaceutical analysis, phenytoin sodium and procaine hydrochloride were titrated with AgNO_3 and NaOH solutions, respectively. Results With our new titrator and nephelometric sensor, the accuracy and precision of our new titrimetry can be better than 0.2% under suitable conditions. Conclusion This new titrimetry can be used for pharmaceutical analysis.