氟离子选择电极法测定氟化钙含量

Determination of Calcium Fluoride Content by A Fluoride Ion Selective Electrode Method

采用氟离子选择电极法测定氰氨化钙炉料中氟化钙的含量,进行了条件和应用试验。结果表明较佳的条件为:用15mL的盐酸和硼酸混合酸溶解样品,加热时间3min;样品称样量0.5g(准至0.1mg),当w(CaF2)≤1.0%和w(CaF2)=1.0%～2.0%时,测定样品的体积分别为20mL和10mL;先用氢氧化钠溶液将pH值调节至～7,再用乙酸钠调至5～6。在此条件下,测定样品的标准偏差<0.03%,RSD<4%,加标回收率为98%～103%;与EDTA容量滴定法比较,平行误差小、准确度好。该方法可以准确测定出氰氨化钙炉料中氟化钙的含量。

Calcium fluoride content in calcium cyanamide charging is determined by a fluoride ion selective electrode method, and its conditions and applications are tested. Results show that the better conditions are as follows:mixture of 15 mL hydrochloric acid and boric acid is used to dissolve the sample, and heated 3 min; the sample is weighed 0.5 g (precision at 0.1 mg). At w(CaF2)≤1.0% and w(CaF2)=1.0%-2.0%, vol of the sample is determined to be 20 mL and 10 mL, respectively; its pH is adjusted to ～7 with sodium hydroxide solution, followed by sodium acetate to 5-6. Under this condition, standard deviation of the determined sample is<0.03%, RSD<4%, indexed recovery 98%-103%; compared with EDTA precipitation titration method, there are few parallel errors and good in precision. This method can exactly determine calcium fluoride in the calcium cyanamide charging.