Saleh Sfoog H, Tripp Carl P
Department of Chemistry, University of Maine, Orono, 04469, Maine, USA; Frontier Institute for Research in Sensor Technologies (FIRST), University of Maine, Orono, 04469, Maine, USA.
Department of Chemistry, University of Maine, Orono, 04469, Maine, USA; Frontier Institute for Research in Sensor Technologies (FIRST), University of Maine, Orono, 04469, Maine, USA.
Talanta. 2021 Jun 1;228:122250. doi: 10.1016/j.talanta.2021.122250. Epub 2021 Feb 26.
A simple method for measuring water concentration from 1 to 10000 mg L is described. The approach involves adding CaO powder to an oil sample and measuring the amount of Ca(OH) produced by the reaction of CaO with water. Collection of the powder occurs by passing a fixed volume of the oil through an infrared transparent membrane and the amount of water is determined from the intensity of the OH stretching mode of Ca(OH) at 3645 cm. The approach is demonstrated with transmission, vegetable, and extreme pressure oils. These oils represent classes of oils that are problematic for measurement by transmission infrared spectroscopy, using a fixed pathlength cell, as described in ASTM method E2412. Values for the water levels equivalent to those measured by Karl Fischer titration are obtained with a linearity R value of > 0.996 and %RSD of 6.7% over a wide detection range of 1 mg L to 10000 mg L. No calibration is required, as the amount of water is determined using the extinction coefficient for the band at 3645 cm.
描述了一种测量浓度范围为1至10000 mg/L水含量的简单方法。该方法是向油样中加入CaO粉末，并测量CaO与水反应生成的Ca(OH)₂的量。通过使固定体积的油通过红外透明膜来收集粉末，根据Ca(OH)₂在3645 cm处OH伸缩振动模式的强度来确定水的含量。用透平油、植物油和极压油对该方法进行了验证。这些油代表了如ASTM方法E2412中所述的，使用固定光程池通过透射红外光谱法测量时存在问题的几类油。在1 mg/L至10000 mg/L的宽检测范围内，获得了与卡尔费休滴定法测量值相当的水位值，线性R值> 0.996，相对标准偏差（%RSD）为6.7%。由于使用3645 cm处谱带的消光系数来确定水的含量，因此无需校准。
