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目的采用反滴定法、电位滴定法以及离子色谱法分别对皂类产品中的氯含量进行分析和比较。方法反滴定法采用硫氰酸铵和硝酸银标准溶液进行滴定。电位滴定法采用银电极作为指示电极,硝酸银作为标准溶液滴定。离子色谱法采用Ion Pac AS19阴离子交换色谱柱分离,淋洗液为20 mmol/L KOH溶液,以电导检测器检测。通过对市售6个香皂样品的检测结果分析,进行3种方法的比较。结果反滴定法、电位滴定法、离子色谱法的相对误差为1.2%~2.0%、1.5%~2.2%和0.9%~1.7%;相对标准偏差分别为0.009%~0.014%、0.013%~0.016%和0.008%~0.012%;加标回收率分别为101.9%±4.6%、99.8%±8.3%和101.9%±3.0%。结论从精密度、准确度和加标回收率来看,离子色谱法检测效果最好,值得推广应用。
Objective To analyze and compare the chlorine content of soap products by back titration, potentiometric titration and ion chromatography. Methods Back-titration Titration with ammonium thiocyanate and silver nitrate standard solutions. Potentiometric titration with silver electrode as the indicator electrode, silver nitrate titration as a standard solution. Ion chromatography was performed on an Ion Pac AS19 anion exchange column. The eluent was a 20 mmol / L KOH solution and detected by a conductivity detector. Through the analysis of the test results of six commercially available soap samples, three methods were compared. Results The relative errors of back titration, potentiometric titration and ion chromatography were 1.2% ~ 2.0%, 1.5% ~ 2.2% and 0.9% ~ 1.7%, respectively. The relative standard deviations were 0.009% ~ 0.014%, 0.013% ~ 0.016% And 0.008% -0.012%, respectively. The spiked recoveries were 101.9% ± 4.6%, 99.8% ± 8.3% and 101.9% ± 3.0%, respectively. Conclusion From the aspects of precision, accuracy and spike recovery, ion chromatography has the best detection effect and is worth popularizing and applying.