能斯特方程式斜率变化对饲料添加剂磷酸二氢钙氟含量检测结果的影响  

Influence of Nernst equation slope change on fluorine content of feed additive monocalcium phosphate

作　　者：侯竹艳 HOU Zhuyan(Quality Inspection Center of Phosphorus Chemical Business Unit,Yunnan Phosphate Group Co.,Ltd.,Kunming 650600,China)

机构地区：[1]云南磷化集团有限公司磷化工事业部质检中心,云南昆明650600

出　　处：《磷肥与复肥》2023年第8期36-38,共3页Phosphate & Compound Fertilizer

摘　　要：氟电极和饱和甘汞电极在被测试液中的电位差可随溶液中氟离子活度变化而改变,其电位变化规律符合能斯特方程式。验证实验室环境温度改变对磷酸二氢钙氟含量检测结果的影响。结果表明,随着温度上升,标准曲线直线斜率逐渐增大,25℃下饲料添加剂磷酸二氢钙氟含量检测结果也随着升高。此外易与氟离子形成络合物的Fe^(3+)、Al^(3+)、SiO_(3)^(2-)等干扰氟含量测定,通常用总离子强度缓冲溶液消除干扰离子及酸度的影响。氟标准溶液酸度过高时,总离子强度缓冲溶液的缓冲能力无法调节其酸度使其符合氟离子选择性电极法控制要求(pH 5~6),饲料添加剂磷酸二氢钙氟含量检测结果高于真实值350 mg/kg以上。The potential difference between fluoride electrode and saturated calomel electrode in the tested solution can change with the change of fluoride ion activity,and the potential change law conforms to Nernst equation.The influence of the temperature change on the fluoride content of monocalcium phosphate is verified.The experiment shows that with the temperature rising,the linear slope of the standard curve gradually increases,and the fluorine content of the feed additive monocalcium phosphate increases at normal temperature.In addition,Fe^(3+),Al^(3+),SiO_(3)^(2-),etc.,which are easy to form complex with fluorine ions,interfere the determination of fluorine content.Generally,the total ionic strength buffer solution is used to eliminate the influence of interfering ions and acidity.When the acidity of the fluoride standard solution is too high,the acidity of the solution cannot meet the control requirements of the fluoride ion selective electrode method(pH 5-6)when adjusted by the buffering capacity of the total ionic strength buffer solution,and the fluoride content of feed additive monocalcium phosphate is more than 350 mg/kg higher than the true value.

关 键 词：能斯特方程 斜率 饲料添加剂磷酸二氢钙 氟含量 

分 类 号：TQ041.7[化学工程]