检测土壤中全碘的硫氰酸铁-亚硝酸钠-碘催化比色法

Determination of Iodine in Soil by Colorimetric Method with Ferric Thiocyanate and Sodium Nitrite

在稀硝酸溶液中 ,硫氰酸铁的褪色反应与体系中碘的含量、体系温度和反应时间有关 ,硫氰酸铁的质量浓度随时间的变化而减小 ,给检测带来较大误差。作者在体系反应一定时间之后加入颜色固定剂 ,使体系的吸光度在数小时内保持不变 ,提高了检测的准确度。

The decoloration rate of ferric thiocyanate depends on the iodine concentration, temperature and reaction time in a dilute nitric acid solution. Significant errors come from the rapid decoloration of ferric thiocyanate. In this paper, color stabilizers are introduced. These additives can keep the absorbance unchanged for hours, and thus improve the measurement accuracy.