离子选择电极法测定矿物饲料及矿物肥料中的氟

Determination of fluorine in mineral forages and mineral fertilizers by fluorine ion-selective electrode

介绍了测定矿物饲料和矿物肥料中氟含量的通用方法——氟离子选择电极法.探讨了酸溶氟作为有效氟的合理性.通过碱熔-酸提取、盐酸-电热板直接加热、盐酸-水浴加热、盐酸-常温4种溶样方式的比较,选择盐酸-电热板直接加热溶解样品,验证了盐酸溶解样品的可行性.通过调整溶液pH值和采用柠檬酸钠做抗干扰剂和总离子强度缓冲剂,基本消除了基体和共存元素的干扰.用该方法每隔0.5h测定1次样品电位值,4个样品连续4h测定结果的RSD分别为8.4%,7.5%,9.32%,7.38%(n=8),回收率在93.8%～103.7%.该方法操作简便易行,结果令人满意.

A method based on ISE was introduced for the determination of fluoride in mineral forages and mineral fertilizers. The samples were decomposed by HCl and then the fluorine content were determined by ion-selective electrode. The interferences of coexistent elements were discussed and eliminated. The relative standard deviation （RSD） of this method was between 7.38%-9.32% ,and recoveries were 93.8%-103.7%. The results indicate that the method was simple, rapid and accurate.