卡尔·费休库仑法测量气体水分的研究

Research of Karl Fischer Coulometry for the Water Content in Gas Samples

卡尔·费休库仑法是一种测定水分含量的经典方法,具有较高灵敏度和准确度,在气体水分含量测定领域具有一定的应用潜力。本文采用比较法研究卡尔·费休库仑法测量气体水分的准确度,即将湿度发生器产生的稳定湿气分别提供给经校准过的精密露点仪和卡尔·费休库仑法水分仪进行测定。研究起始漂移值和进样量等因素对测量结果重复性的影响,结果表明降低起始漂移值和增大进样量能提高测量结果的重复性;研究卡尔·费休试剂中甲醇含量对反应的影响,结果表明甲醇含量越低,示值误差越大;研究露点在-60^-16℃范围内卡尔·费休法的准确度,结果表明,在水分含量较高的范围(露点:-50.5^-19.9℃)内,卡尔·费休法露点示值误差较小0.4~2.6℃;在水分含量较低(露点:-58.1℃)时,卡尔·费休法露点示值误差为-5.9℃。上述研究结果对卡尔·费休库仑法用于气体水分含量的测定具有一定参考意义。

Karl Fischer coulometry is a classical method for the determination of water content. It has a potential in the determination of water content in gas owing to its high sensitivity and accuracy. In present study,a comparison method was employed to investigate the accuracy of Karl Fischer method for water content in gas,namely the gas with a stable humidity produced by a humidity generator was provided to the dew-point meter and Karl Fischer coulometer simultaneously. The effects of initial drift and sample mass on the repeatability of water content were investigated. It indicated that the lower initial drift and larger sample mass make more repeatable results. The effects of methanol content in the Karl Fischer reagent on the reaction were investigated. It indicated that the lower the methanol content,the greater the indication error. The accuracy of Karl Fischer coulometry for the gas with a dew-point in the range of-60 --16℃ was investigated. It indicated that the error of Karl Fischer coulometry 0. 4 - 2. 6℃ was small with a dew-point of-50. 5 --19. 9℃. However,the error Karl Fischer coulometry was-5. 9℃ with a dew-point of-58. 1℃. These results were valuable reference for the application of Karl Fischer coulometry for the water content in gas.