The determination of water content in crude oil is important for oil transportation, refining, and trade. However, the sensitivity and accuracy of the conventional azeotropic distillation (AD) method are inadequate. Karl Fischer titration methods may give false high results because of the reducing sulfur compounds in crude oil. The present study developed an azeotropic distillation Karl Fischer coulometric titration (AD-KFCT) method which required a modified instrument and a new calibration procedure. The method was modified to decrease the interference caused by reducing sulfur compounds. A certified reference material for water content in liquid was used to determine the recovery of water mass achieved using the AD-KFCT method. The effect of the sample polarity on the method accuracy was assessed. The relative error and relative standard deviations of the water content in three crude oils containing known amounts of water were −7.5% to 2.9% and 0.4% to 6.0%, respectively. The interference by reducing sulfur compounds was studied. The crude oil containing 1-propanethiol was measured using a sulfur dioxide-free anolyte, and the amount of iodine consumed by the distilled 1-propanethiol was determined. The contribution of 1-propanethiol was then subtracted from the water content measured using the normal Karl Fischer reagent. Finally, the relative error of the modified water content in the crude oil samples containing 1-propanethiol was −4.4% to 0.7%. Therefore, the modified AD-KFCT method is accurate and convenient for crude oil.

原油中水含量的测定对于石油运输，精炼和贸易至关重要。然而，常规共沸蒸馏（AD）方法的灵敏度和准确性不足。由于减少了原油中的硫化合物，卡尔·费休滴定法可能会得出错误的高结果。本研究开发了一种共沸蒸馏卡尔·费休电量滴定法（AD-KFCT），该方法需要改进的仪器和新的校准程序。对该方法进行了修改，以减少由还原硫化合物引起的干扰。使用经过认证的液体中水分含量的参考物质来确定使用AD-KFCT方法获得的水量回收率。评估了样品极性对方法准确性的影响。三种含水量已知的原油中水含量的相对误差和相对标准偏差分别为-7.5％至2.9％和0.4％至6.0％。对还原性硫化合物的干扰进行了研究。使用无二氧化硫的阳极液测量含1-丙硫醇的原油，并测定蒸馏的1-丙硫醇消耗的碘量。然后从使用常规Karl Fischer试剂测得的水含量中减去1-丙硫醇的贡献。最后，含1-丙硫醇的原油样品中改性水含量的相对误差为-4.4％至0.7％。因此，改进的AD-KFCT方法对于原油是准确且方便的。分别。研究了还原性硫化合物的干扰。使用无二氧化硫的阳极液测量含1-丙硫醇的原油，并测定蒸馏的1-丙硫醇消耗的碘量。然后从使用常规卡尔·费休试剂测得的水含量中减去1-丙硫醇的贡献。最后，含1-丙硫醇的原油样品中改性水含量的相对误差为-4.4％至0.7％。因此，改进的AD-KFCT方法对于原油是准确且方便的。分别。对还原性硫化合物的干扰进行了研究。使用不含二氧化硫的阳极液测量含1-丙硫醇的原油，并测定蒸馏的1-丙硫醇消耗的碘量。然后从使用常规卡尔·费休试剂测得的水含量中减去1-丙硫醇的贡献。最后，含1-丙硫醇的原油样品中改性水含量的相对误差为-4.4％至0.7％。因此，改进的AD-KFCT方法对于原油是准确且方便的。然后从使用常规卡尔·费休试剂测得的水含量中减去1-丙硫醇的贡献。最后，含1-丙硫醇的原油样品中改性水含量的相对误差为-4.4％至0.7％。因此，改进的AD-KFCT方法对于原油是准确且方便的。然后从使用常规卡尔·费休试剂测得的水含量中减去1-丙硫醇的贡献。最后，含1-丙硫醇的原油样品中改性水含量的相对误差为-4.4％至0.7％。因此，改进的AD-KFCT方法对于原油是准确且方便的。