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快速法测定草甘膦过去是采用溴百里酚蓝酸碱指示剂,其滴定终点是间接指示的。在滴定过程中需要往返滴定,终点的判断较为困难,因而容易产生误差。为提高准确度,曾改用汞电极作指示电极进行电位滴定,效果较好,可以消除主观误差,但突变范围狭窄,只局限于数字离子计才适用,这对一般生产厂在推广使用上受到仪器限制。因此,探索较理想的金属指示剂,具有更积极的现实意义。经过一段时间的摸索和试验,认为试液中加入少量碘化钾,在滴定过程中,沉淀变化较明显,终点易于判断,操作更为简便,结果令人满意。
Rapid determination of glyphosate used bromothymol blue acid-base indicator, the titration of the end point is indirectly indicated. In the titration process requires back and forth titration, the judgment of the end point is more difficult, and therefore prone to error. In order to improve the accuracy, the mercury electrode was used as the indicator electrode for potential titration, the effect is better, which can eliminate the subjective error, but the mutation range is narrow, only limited to the digital ion meter was only applicable to the general use of the plant in promoting the use of Instrument limitations. Therefore, to explore the ideal metal indicator has a more positive and practical significance. After a period of groping and testing, that a small amount of potassium iodide test solution, the titration process, the precipitation changes significantly, the end point is easy to judge, the operation is more simple, the results are satisfactory.