Prediction of soil organic carbon partition coefficients by soil column liquid chromatography

Abstract

To avoid the limitation of the widely used prediction methods of soil organic carbon partition coefficients ( K OC) from hydrophobic parameters, e.g., the n-octanol/water partition coefficients ( K OW) and the reversed phase high performance liquid chromatographic (RP-HPLC) retention factors, the soil column liquid chromatographic (SCLC) method was developed for K OC prediction. The real soils were used as the packing materials of RP-HPLC columns, and the correlations between the retention factors of organic compounds on soil columns ( k soil) and K OC measured by batch equilibrium method were studied. Good correlations were achieved between k soil and K OC for three types of soils with different properties. All the square of the correlation coefficients ( R 2) of the linear regression between log k soi and log K OC were higher than 0.89 with standard deviations of less than 0.21. In addition, the prediction of K OC from K OW and the RP-HPLC retention factors on cyanopropyl (CN) stationary phase ( k CN) was comparatively evaluated for the three types of soils. The results show that the prediction of K OC from k CN and K OW is only applicable to some specific types of soils. The results obtained in the present study proved that the SCLC method is appropriate for the K OC prediction for different types of soils, however the applicability of using hydrophobic parameters to predict K OC largely depends on the properties of soil concerned.