Certification by the Karl Fischer method of the water content in SRM 2890, Water Saturated 1-Octanol, and the analysis of associated interlaboratory bias in the measurement process

Abstract

The calibration of Karl Fischer instruments and reagents and the compensation for instrumental bias are essential to the accurate measurement of trace levels of water in organic and inorganic chemicals. A stable, nonhygroscopic standard, Water Saturated Octanol, which is compatible with the Karl Fischer reagents, has been prepared. This material, Standard Reference Material (SRM) 2890, is homogeneous and is certified to contain 39.24 +/- 0.85 mg water/mL (expanded uncertainty) of solution (47.3 +/- 1.0 mg water/g solution, expanded uncertainty) at 21.5 degrees C. The solubility of water in -octanol has been shown to be nearly constant between 10 degrees C and 30 degrees C (i.e., within 1% of the value at 21.5 degrees C). The results of an interlaboratory comparison exercise illustrate the utility of SRM 2890 in assessing the accuracy and bias of Karl Fischer instruments and measurements.

Drug-Membrane Interactions Studied in Phospholipid Monolayers Adsorbed on Nonporous Alkylated Microspheres

“…These regression coefficient values are in close agreement with the notion that the nonpolar compounds are only partitioning in the nonpolar phase of 1-octanol and do not enter the aggregates of water molecules hydrating the hydroxyl groups of 1-octanol. The water aggregates make the overall volume of the nonpolar phase about 4% smaller than the overall volume of 1-octanol; 63 therefore, the P o/w values are slightly smaller than the P a/w values, in accordance with the slightly positive intercept. This equation was used to calculate the logP a/w values, which are listed in Table 1, along with the experimentally available values.…”

Characterization of Certified Reference Material for the Quantification of Water in Bioethanol

“…NIST SRM 2890 19 was analyzed by coulometric and volumetric KF titrations. No significant difference was observed between the measured and certified values.…”

Thermochemistry of the reaction { phospho enol pyruvate(aq)+d -erythrose 4-phosphate(aq) + H2 O(l) = 2-dehydro-3-deoxy- d - arabino -heptonate 7-phosphate(aq) + phosphate(aq) }

“…Calibration was done with a water-saturated octanol solution. (15) An appropriate correction for the presence of water in the phosphoenolpyruvate †Certain commercial equipment, instruments, or materials are identified in this paper to specify the experimental procedures adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute of Standards and Technology, nor is it intended to imply that the materials or equipment identified are necessarily the best available for the purpose.…”

“…The calorimetrically determined molar enthalpy for this biochemical reaction is r H m (cal) = −(67.7 ± 1.5) kJ · mol −1 at T = 298. 15 …”