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目的:建立一种快速、准确的测定直发产品中游离氢氧化物的方法。方法:直发产品中游离氢氧化物与盐酸发生中和反应,pH复合玻璃电极上电位发生变化,在溶液pH=9.2时自动记录盐酸标准溶液的滴定量,从而计算出样品中游离氢氧化物含量。结果:自动电位滴定仪法的精密度优于人工滴定法,相对标准偏差为0.55%;方法有较好的准确度,三组样品测得的平均加标回收率为97.6%～102.9%,总平均加标回收率为98.9%;方法中抽真空法去除氨效果良好。结论:运用自动电位滴定法测定直发膏(剂)类样品中的游离氢氧化物,方法简便、快速、准确,该方法适合批量检测,实用性强。
Objective: To establish a rapid and accurate method for the determination of free hydroxide in hair straightening products. Methods: Neutralization reaction between free hydroxide and hydrochloric acid was carried out in the straight hair products. The potential of the pH composite glass electrode changed. When the pH of the solution was 9.2, the titration of the hydrochloric acid standard solution was automatically recorded to calculate the free hydroxide content. Results: The precision of automatic potentiometric titration was better than that of artificial titration, the relative standard deviation was 0.55%. The average accuracy of the method was 97.6% -102.9% The average spike recovery was 98.9%; the method of vacuum to remove ammonia effect is good. Conclusion: The method of automatic potentiometric titration for the determination of free hydroxide in the sample of straight hair cream is simple, rapid and accurate. The method is suitable for mass detection and has strong practicability.