【摘要】 当待测液中氟离子浓度较低时氟离子选择电极的电位响应与浓度变化呈非线性关系，造成测定结果发生偏离，从而影响氟离子浓度测定的准确性。为探究氟离子选择电极测定低氟样品时的测定下限和影响情况，以不同性能的离子选择电极和不同浓度梯度待测溶液为研究对象，考察电极电位响应与待测溶液浓度的关系，评估其对测定结果准确度的影响，并提出采用二次标准加入法校正低浓度氟溶液测定偏差。结果表明：电极的能斯特响应临界浓度与其自身性能有关，长时间使用或放置会使临界浓度增大；当待测液浓度低于临界浓度时，采用一次标准加入法测定的氟含量值显著高于理论值，相对误差为28%～364%;使用二次标准加入法，可将干扰较少的待测液定量下限减小至0.02μg/mL,可将基体待测液定量下限减小至0.10μg/mL,测定相对偏差小于10%。更多还原

【Abstract】 When the concentration of fluoride ion in the liquid to be tested is lower, the potential response of the fluoride ion selective electrode is nonlinear with the concentration change, which causes the deviation of the measurement result and affects the accuracy.In order to explore the lower limit and influence of fluoride ion selective electrode in the determination of low fluorine samples, the relationship between the electrode potential response and the solution concentration was investigated by taking ion selective electrodes with different properties and solutions with different concentration gradients as the research object.The influence on the accuracy of sample analysis was evaluated and the secondary standard solution addition method was proposed to correct the measured deviation of low concentration fluorine solution.The results show that: the critical concentration of the Nernst response is related to the performance of the electrode; the critical concentration would increase if the electrode is used or placed for a long time; when the sample concentration is lower than the critical concentration, the measured value of fluorine content by standard solution addition method is significantly higher than the theoretical value, the relative errors are 28%～364%.With secondary standard addition method, the lower limit of determination can be obtained, the limit of quantitation of non-interference samples solutions can be extended to 0.02 μg/mL,the matrix sample solutions can be expanded to 0.10 μg/mL,and the relative deviation is less than 10%.更多还原