表面活性剂碱度测定方法的改进和验证

Improvement and verification of alkalinity determination method of surfactant

表面活性剂碱度的检测主要依照国标GB/T 7378-1996中的方法,使用手动滴定、依据指示剂来判断滴定终点。本文基于全自动电位滴定仪对国标方法进行了改进和验证,建立了表面活性剂碱度测定的光度滴定法和电位滴定法,并对两种改进方法进行了验证。改进后的方法分别根据光度电极和电位电极的突跃点来判断滴定终点,判断更准确,与国标方法的结果相一致,重复性RSD≤3.0%。在国标方法基础上改进的光度滴定法和电位滴定法,滴定体积控制精确、自动化程度高、重复性和准确性好,可作为国标方法的改进方法用于实际检测。

The alkalinity of surfactant is detected mainly according to the method in the national standard GB/T 7378-1996, using manual titration and judging the titration end point according to the indicator. In this paper, the national standard method was improved and verified based on the automatic potentiometric titrator. The photometric titration and potentiometric titration for the determination of surfactant alkalinity were established and verified. The improved method judges the titration end point according to the jump points of photometric electrode and potential electrode, respectively. The end point judgment was more accurate, the evaluation of the consistency with the results of the national standard method was ideal, and the RSD values of the repeatability evaluation results were no more than 3.0%. The improved photometric titration and potentiometric titration methods based on the national standard method have accurate titration volume control, high degree of automation, good repeatability and accuracy, and can be used as the improved method for practical detection.