Margolis S A
Analytical Chemistry Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899.
Anal Chem. 1999 May 1;71(9):1728-32. doi: 10.1021/ac981137z.
The disparity between the volumetric and coulometric Karl Fischer methods for the measurement of water in hydrocarbons and hydrocarbon mixtures (oils) has been resolved. The amount of water detected by the volumetric method when the titration vessel solution is homogeneous is higher than that measured coulometrically or volumetrically when the titration vessel solution is heterogeneous. Water in oil that is not measured by the coulometric method when the oil is incompletely dissolved has been shown to reside in the oil phase of the heterogeneous (multiphasic) coulometric vessel suspension. Water that is not measured volumetrically under relatively low chloroform concentrations after the point of transition to a heterogeneous titration vessel solution is reached also appears to reside in the nonaqueous phase of the titration vessel solution. It appears that this water is retained in the hydrocarbon phase in a manner such that it is completely inaccessible to the volumetric or coulometric Karl Fischer reagents.
用于测量烃类和烃类混合物（油类）中水分的容量法卡尔费休法和库仑法卡尔费休法之间的差异已得到解决。当滴定容器溶液均匀时，容量法检测到的水量高于滴定容器溶液不均匀时库仑法或容量法测得的水量。当油不完全溶解时，库仑法无法测量的油中的水分已被证明存在于非均匀（多相）库仑容器悬浮液的油相中。在达到向不均匀滴定容器溶液转变点后，在相对较低氯仿浓度下容量法未测量到的水分似乎也存在于滴定容器溶液的非水相中。看来这种水分以某种方式保留在烃相中，使得容量法或库仑法卡尔费休试剂完全无法接触到它。
