红外吸收法测定碳酸镧和碳酸铈中不可吹扫有机碳

采用5mL盐酸将试样溶解完全,将氧气通入试液中进行吹扫,除去溶液中溶解的二氧化碳和易挥发性有机物后,将试液注入高温燃烧管中,在专用催化剂存在下进行热催化高温氧化反应,使有机碳转化成二氧化碳,用非色散红外检测器进行测定,建立了红外吸收法测定碳酸镧和碳酸铈中不可吹扫有机碳(NPOC)含量的方法。采用正交试验法选择了吹扫二氧化碳和易挥发有机物的最佳试液体积为25mL、吹扫时间为300s、试液pH值为1.0。NPOC校准曲线相关系数为0.999 9,线性关系良好,方法检出限为0.000 6%,方法的测定下限为0.001 9%。采用实验方法对碳酸镧和碳酸铈中NPOC进行测定,结果的相对标准偏差(RSD,n=11)小于5.0%,加标回收率在95%~104%之间。

Determination of non-purgeable organic carbon in lanthanum carbonate and cerium carbonate by infrared absorption method

The sample was dissolved in 5 mL of hydrochloric acid completely and oxygen as a purging gas was pumped into the test solution for removing carbon dioxide and volatile organic compounds dissolved in the solution. The test solution was then injected into a high-temperature combustion tube and has thermocatalytic high-temperature oxidation reaction in the presence of a special catalyst acceleration to convert organic carbon in the test solution into carbon dioxide. The obtained solution was determined by non-dispersive infrared detector,which established an infrared absorption method for the determination of non-purgeable organic carbon (NPOC) in lanthanum carbonate and cerium carbonate. The orthogonal test was used to select the optimum test solution volume as 25 mL,the purge time as 300 s and the pH value as 1.0 for purging carbon dioxide and volatile organic compounds. The correlation coefficient of NPOC calibration curve was 0.999 9 with good linearity. The detection limit of NPOC was 0.000 6%,and the lower limit of determination was 0.001 9%. The content of NPOC in lanthanum carbonate and cerium carbonate was determined by proposed method,and the relative standard deviation(RSD,n=11)was less than 5.0%.The recoveries ranged were from 95% to 104%.