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四苯硼钠直接滴定法可以测定季铵盐类杀菌剂、洗涤剂和表面活性剂等,但由于四苯硼钠不稳定、易分解,故标准液须每次临用前标定,较为不便。我们根据四苯硼钠能与K~+定量生成沉淀的性质,设计了以氯化钾为基准的测定季铵盐类新方法,四苯硼钠液不必标定,具有简便、快速、准确的特点。1 试剂四苯硼钠溶液:0.02mol·L~(-1),按中国药典(1990版)二部附录177页配制,不必标定。溴酚蓝指示剂:取溴酚蓝0.1g,加0.05mol·L~(-1)氢氧化钠3ml使其溶解,加水稀释至200ml。乙酸-乙酸钠缓冲液:pH 3.7,取无水乙酸钠20g,加水300ml溶解后,加溴酚蓝指示剂1ml,加冰乙酸(约60～80ml)至蓝色转变成纯绿色,再加水稀释至1000ml。
Sodium tetraphenylborate direct titration method can be quaternary ammonium salts fungicides, detergents and surfactants, but because of tetraphenylboron sodium instability, easy to decompose, so the standard solution before each calibration, more inconvenient. Based on the property that sodium tetraphenylborate can quantitatively form precipitation with K ~ +, we designed a new method for the determination of quaternary ammonium salts based on potassium chloride. Sodium tetraphenylborate solution has no need of calibration, which is simple, rapid and accurate . 1 Reagents Sodium tetraphenylborate solution: 0.02mol · L -1, according to the Chinese Pharmacopoeia (1990 edition) two Appendix 177 preparation, do not need calibration. Bromophenol blue indicator: Take bromophenol blue 0.1g, add 0.05mol·L -1 sodium hydroxide 3ml to dissolve, diluted with water to 200ml. Acetic acid - sodium acetate buffer: pH 3.7, take anhydrous sodium acetate 20g, add water 300ml dissolved, add bromophenol blue indicator 1ml, add glacial acetic acid (about 60 ~ 80ml) to blue to change into pure green, To 1000ml.