SOIL WATER CONTENT BY KARL FISCHER TITRATION

摘要

Specific analytical determination of water content is often desirable in contaminated soils. Karl Fischer (KF) titration is useful for this purpose, since it consumes only H_2O, even in the presence of other volatile substances. Although widely used for water content determination in industrial and food products, KF has been virtually ignored in soil and environmental science. Oven drying (OD), conversely, is considered the standard method of soil water determination, but is an indiscriminate determiner of all volatiles.rnWe examined KF titration for soil water content determination. Two soil types (sand and loam) were mixed with varying amounts of water (0 to 240 g kg~(-1)) and octane or toluene (0 to 128 g kg~(-1)). The prepared samples containing water only, water and octane, and water and toluene were analyzed for volatile/moisture content using OD/KF analysis. Soil moisture values determined by our calibrated KF method (w_c) compared favorably to those determined by OD (w_o) in terms of regression slope, intercept, correlation coefficient, and Student's t. Regression slopes ranged from 0.980 to 1.009 while intercepts ranged from -0.6 to 7.8 g kg~(-1). Plots of the data show essentially a 1:1 correspondence of w_c to w_o.